FOUR TRIALS WERE CONDUCTED AT THE UFSâS EXPERIMENTAL FARM TO EVALUATE, AND DEVELOP A MORE EFFICIENT PROTOCOL FOR SUPEROVULATION AND EMBRYO CRYOPRESERVATION AND TRANSFER METHODS IN BOER GOATS. EACH TRIAL WAS CONDUCTED WITH SPECIFIC OBJECTIVES. THE FIRST TWO TRIALS WERE CONDUCTED DURING THE AUTUMN AND SPRING SEASONS OF 2005, TO EVALUATE THE OVARIAN RESPONSE OF BOER GOAT DOES TO SUPEROVULATION AND EMBRYO RECOVERY PROCEDURES FOLLOWING A PRE-TREATMENT WITH A GNRH AGONIST. FURTHER ALSO TO EVALUATE THE EFFECT OF SEASON ON THE OVARIAN RESPONSE TO SUPEROVULATION. TWENTY-ONE MULTIPAROUS MATURE BOER GOAT DOES WERE USED AS DONORS DURING THE NATURAL BREEDING SEASON (AUTUMN). IN ALL DOES, THE ONSET OF THE OESTRUS WAS SYNCHRONISED WITH CIDRâS INSERTED INTRAVAGINALLY FOR A PERIOD OF 17 DAYS. DOES WERE ALL SUPEROVULATED WITH 200 MG PFSH/DOE ADMINISTERED I.M. IN 7 DOSAGES, AT 12H INTERVALS, STARTING 48H PRIOR TO CIDR REMOVAL. THE TREATMENT GROUP RECEIVED A GNRH AGONIST (GNRHA) (40μG/DAY/DOE) TREATMENT, ADMINISTERED AS 2 INJECTIONS PER DAY FOR 7 DAYS, STARTING ON DAY 8 OF CIDR INSERTION. THE CONTROL DOES WERE SYNCHRONISED AND SUPEROVULATED, BUT RECEIVED NO GNRHA. OESTROUS DETECTION WAS PERFORMED TWICE DAILY PRIOR TO PROGESTAGEN TREATMENT (CIDR APPLICATION) AND AT 8H INTERVALS FOLLOWING CIDR REMOVAL FOR A PERIOD OF 72H. FIXED-TIME LAPAROSCOPIC AI WITH DILUTED BOER GOAT SEMEN WAS PERFORMED 36 AND 48H FOLLOWING CIDR REMOVAL. BLOOD SAMPLES WERE ALSO COLLECTED FROM 5 ANIMALS IN EACH GROUP AT 4 DAY INTERVALS DURING PROGESTAGEN TREATMENT AND AT DAY 14 OF PROGESTAGEN TREATMENT TO EVALUATE THE HORMONAL EFFECT OF GNRHA TREATMENT. FROM SUPEROVULATION TREATMENT UNTIL CIDR REMOVAL, BLOOD SAMPLES WERE COLLECTED TWICE DAILY AND THEN AT 8H INTERVALS FROM CIDR REMOVAL FOR A PERIOD OF 3 DAYS. THE BLOOD SAMPLES WERE ALSO TAKEN AT 24 H INTERVALS FOLLOWING THE SECOND AI UNTIL EMBRYO FLUSHING (DAY 6 FOLLOWING AI). SERUM PROGESTERONE AND OESTROGEN CONCENTRATIONS WERE DETERMINED VIA RADIOIMMUNOASSAY. EMBRYOS WERE THEN FINALLY SURGICALLY RECOVERED (DAY 6) UNDER GENERAL ANAESTHESIA. THE OESTROUS SYNCHRONISATION RESPONSE WAS EVALUATED BASED ON THE OCCURRENCE OF OESTRUS, TIME TO ONSET OF OESTROUS AND DURATION OF THE INDUCED OESTROUS PERIOD. THE EMBRYO YIELD AND QUALITY WAS ALSO EVALUATED. ONLY 81% OF THE DOES EXHIBITED OVERT SIGNS OF OESTRUS PRIOR TO SYNCHRONISATION TREATMENT APPLICATION (INDICATION OF CYCLIC ACTIVITY). THE MEAN DURATION OF THESE NATURAL OESTROUS CYCLES WAS RECORDED AS 20.1±3.5D, WHILE THE NATURAL OESTROUS PERIOD LASTED FOR 37.7±11.9H. FOLLOWING SYNCHRONISATION AND SUPEROVULATION TREATMENT, 100% AND 80% OF THE DOES IN THE FSH/GNRHA AND FSH-TREATED DOES SHOWED SIGNS OF OESTRUS, RESPECTIVELY. THE TIME INTERVAL FROM CIDR REMOVAL TO ONSET OF OESTRUS AND DURATION OF THE INDUCED OESTROUS PERIOD DID NOT DIFFER SIGNIFICANTLY, ALTHOUGH THE DURATION OF THE INDUCED OESTROUS PERIOD IN THE FSH/GNRHA GROUP (19.6±5.5H) TENDED TO BE SHORTER, COMPARED TO THE FSH-TREATED DOES (25.0±7.4H). THE OCCURRENCE OF ABNORMAL CLâS WAS 38.1% IN TOTAL, WHILE 23.8% OF THE DOES DID NOT HAVE ANY CLâS. THERE WERE NO SIGNIFICANT DIFFERENCES IN EMBRYO YIELD AND QUALITY PARAMETERS MEASURED. IN DOES PRE-TREATED WITH GNRHA HOWEVER, THE NUMBER OF DEGENERATE EMBRYOS TENDED TO BE HIGHER, WHILE THE NUMBER OF TRANSFERABLE EMBRYOS TENDED TO BE LOWER, COMPARED TO THE CONTROL (FSH) DOES (6.6±4.2 VS. 1.7±1.5 AND 3.4±2.7 VS. 9.3±6.1, RESPECTIVELY). THE SECOND TRIAL REPEATING ALL THE PROCEDURES PERFORMED IN THE FIRST TRIAL WAS CONDUCTED IN THE SPRING OF 2005 (OUTSIDE THE BREEDING SEASON), USING 22 MULTIPAROUS BOER GOAT DOES AS RECIPIENTS. ONLY 45.5% OF THE DOES SHOWED OVERT SIGNS OF OESTRUS PRIOR TO THE APPLICATION OF OESTROUS SYNCHRONISATION AND SUPEROVULATION TREATMENT. GNRHA TREATMENT HAD NO BENEFICIAL EFFECT IN RESPONSE TO OESTROUS SYNCHRONISATION AND OVULATION RATE. THE TOTAL MEAN STRUCTURES FLUSHED WAS SIGNIFICANTLY (P<0.05) LOWER IN THE DOES PRETREATED WITH GNRHA (12.6±6.0 PER DOE, COMPARED TO THE CONTROL DOES (17.6±4.9 PER DOE). THE MEAN TOTAL NUMBER OF EMBRYOS COLLECTED PER DONOR AND THE FERTILISATION RATE WERE SIGNIFICANTLY (P<0.05) LOWER IN DOES PRETREATED WITH GNRHA THAN IN THE FSH-TREATED DOES (11.5.±5.3 VS. 16.5±6.1 AND 81.6±32.2% VS. 92.6±19.5%, RESPECTIVELY). GNRHA TREATMENT HAD NO EFFECT ON THE MEAN NUMBER OF UNFERTILISED OVA PER DONOR. PRE-TREATMENT OF DOES WITH GNRHA HOWEVER RESULTED IN A SIGNIFICANTLY (P<0.01) HIGHER MEAN NUMBER OF DEGENERATIVE EMBRYOS WHEN COMPARED TO THE CONTROL DOES (6.9±4.5 VS. 3.2±4.2 PER DOE). SUBSEQUENTLY, THE NUMBER OF TRANSFERABLE EMBRYOS AND TRANSFERABLE RATE (4.3±4.0 AND 32.7±26.9%) WAS LOWER IN DOES PRE-TREATED WITH GNRHA, COMPARED TO THE CONTROL DOES (13.1±5.3 AND 75.2±26.8%). THE MEAN TIME TO ONSET OF OESTRUS WAS SIGNIFICANTLY (P<0.05) EARLIER DURING THE NATURAL BREEDING SEASON (24.9±4.8H), COMPARED TO OUTSIDE THE BREEDING SEASON IN DOES (30.5±9.1H). SIMILARLY, THE MEAN DURATION OF THE INDUCED OESTRUS WAS SIGNIFICANTLY (P<0.05) LONGER DURING THE NATURAL BREEDING SEASON (24.0±5.7H) - THAN OUTSIDE THE BREEDING SEASON (18.2±3.7H). SEASON DID NOT HAVE ANY SIGNIFICANT EFFECT ON THE TOTAL NUMBER OF CLâS INDUCED, ALTHOUGH THE NUMBER OF CLâS ON THE RIGHT OVARY WAS SIGNIFICANTLY (P<0.05) LOWER DURING THE NATURAL BREEDING SEASON. SEASON DID NOT HAVE EFFECT ON THE NUMBER OF STRUCTURES RECOVERED, EMBRYOS, DEGENERATIVE AND TRANSFERABLE EMBRYOS PER DONOR. THE MEAN NUMBER OF UNFERTILISED OVA PER DONOR (3.3±2.8) WAS SIGNIFICANTLY (P<0.05) HIGHER IN GOATS TREATED OUTSIDE THE NATURAL BREEDING SEASON THAN DURING THE NATURAL BREEDING SEASON (0.9±2.4). IT COULD BE CONCLUDED THAT PRE-TREATMENT WITH GNRHA DOES NOT HAVE ANY BENEFICIAL EFFECT ON OESTROUS RESPONSE, TIME TO ONSET AND DURATION OF THE INDUCED OESTROUS PERIOD. THE ADDITION OF THE GNRHA INTO THE FSH GOAT SUPEROVULATION PROTOCOL REDUCED THE NUMBER OF STRUCTURES RECOVERED, EMBRYO YIELD, AND THE FERTILISATION RATE (THE NUMBER OF EMBRYOS PER STRUCTURES ON OVARIES). THE PRE-TREATMENT WITH GNRHA ALSO INCREASED THE NUMBER OF DEGENERATE EMBRYOS - WHICH ULTIMATELY REDUCED THE TOTAL NUMBER OF TRANSFERABLE EMBRYOS. IT COULD THUS BE RECOMMENDED THAT A PRE-TREATMENT WITH A GNRH AGONIST IN A BOER GOAT MOET PROGRAMME IS NOT WARRANTED. THE SERUM PROGESTERONE CONCENTRATIONS DID NOT DIFFER BETWEEN THE TREATMENT GROUPS, THROUGHOUT THE OESTROUS SYNCHRONISATION PERIOD. AT 48H FOLLOWING THE SECOND AI (96H AFTER CIDR REMOVAL), THE CONTROL DOES RECORDED A SIGNIFICANTLY (P<0.05) HIGHER MEAN SERUM PROGESTERONE CONCENTRATION (11.3±4.9 NG/ML), THAN IN THE FSH/GNRHA-TREATED DOES (4.3±2.1 NG/ML). THE SERUM PROGESTERONE CONCENTRATIONS INCREASED FOLLOWING THE SECOND AI AND WERE HIGHEST ON THE DAY OF EMBRYO FLUSHING IN BOTH GROUPS â WITHOUT ANY SIGNIFICANT DIFFERENCES. THE MEAN SERUM OESTROGEN CONCENTRATION WAS SIGNIFICANTLY (P<0.05) HIGHER ON DAY 12 OF SYNCHRONISATION (5TH DAY OF GNRHA TREATMENT) AND AT THE 4TH PFSH (SUPEROVULATION) INJECTION IN THE FSH/GNRHA TREATED GROUP COMPARED TO THE CONTROL DOES. AT THE TIME OF THE FIRST AI (36H FOLLOWING CIDR REMOVAL) THE MEAN SERUM OESTROGEN CONCENTRATION WAS SIGNIFICANTLY (P<0.05) HIGHER (58.3±26.9 PG/ML) IN THE CONTROL (FSHSTIMULATED) DOES, COMPARED TO THE FSH/GNRHATREATED DOES (15.7±17.4 PG/ML). THE BLOOD HORMONAL LEVELS INDUCED DURING SUPEROVULATION WERE DEPENDENT ON VARIOUS OVARIAN FACTORS WHICH ULTIMATELY DETERMINE THE COMPETENCE OF THE OOCYTES AND EVENTUALLY VIABILITY OF THE EMBRYOS. A THIRD TRIAL WAS CONDUCTED DURING THE NATURAL BREEDING SEASON (AUTUMN, 2006). SEVENTEEN MULTIPAROUS MATURE BOER GOAT DOES WERE USED AS DONORS IN THIS TRIAL TO EVALUATE AND REFINE THE FSH SUPEROVULATORY TREATMENT BY COMPARING TWO ROUTES OF GONADOTROPHIN (PFSH) ADMINISTRATION. HERE 27 RECIPIENTS WERE USED TO EVALUATE THE SURVIVAL RATE OF THE GOAT EMBRYOS FOLLOWING CRYOPRESERVATION USING THE CONVENTIONAL SLOW FREEZING OR VITRIFICATION METHOD. DOES RECEIVED A PFSH SUPEROVULATION TREATMENT INTRAMUSCULAR OR SUBCUTANEOUS, WHILE RECIPIENTS RECEIVED FRESH, SLOW FROZENTHAWED OR VITRIFIED-THAWED EMBRYOS. THE ROUTE OF ADMINISTERING GONADOTROPHIN TREATMENT DID NOT AFFECT THE OESTROUS RESPONSE, THE TIME FROM CIDR REMOVAL TO THE ONSET OF OESTRUS AND DURATION OF THE INDUCED OESTROUS PERIOD. THE ROUTE OF GONADOTROPHIN ADMINISTRATION DID NOT AFFECT THE OVULATION RATE, THE TOTAL NUMBER OF STRUCTURES, NUMBER OF EMBRYOS AND TRANSFERABLE EMBRYOS COLLECTED PER DONOR. THE MEAN NUMBER OF UNFERTILISED OVA IN THE I.M. GROUP (3.3±4.8) WAS SIGNIFICANTLY (P<0.05) HIGHER, THAN IN THE S.C. GROUP (0.3±0.8). SIMILARLY, THE MEAN NUMBER OF DEGENERATED EMBRYOS PER DONOR IN THE DOES ADMINISTERED THE FSH SUBCUTANEOUSLY (5.9±4.5) WAS SIGNIFICANTLY (P<0.05) HIGHER, WHEN COMPARED TO THE INTRAMUSCULAR GROUP (2.6±2.3). A TOTAL OF 88.9% RECIPIENTS DEMONSTRATED SIGNS OF OESTRUS FOLLOWING CIDR REMOVAL. A PREGNANCY RATE OF 85.7%, 50.0% AND 37.5% WAS RECORDED FOLLOWING THE TRANSFER OF FRESH, SLOW-FROZEN AND VITRIFIED EMBRYOS, RESPECTIVELY. EMBRYO SURVIVAL RATES OF 35.7%, 25.0% AND 31.3% WERE THEN EVENTUALLY RECORDED FOLLOWING FRESH, SLOW-FROZEN AND VITRIFIED EMBRYO TRANSFER. IT COULD THUS BE CONCLUDED THAT AN ADVANTAGE OF THE SUBCUTANEOUS ROUTE OF ADMINISTRATION RESULTED IN A LOWER NUMBER OF UNFERTILISED OVA RECOVERED, WHICH WAS HOWEVER NEGATED BY A HIGHER NUMBER OF DEGENERATE EMBRYOS RECORDED. THEREFORE BOTH ROUTES CAN BE USED FOR THE ADMINISTRATION OF PFSH SUPEROVULATION TREATMENT IN BOER GOAT DOES DURING THE BREEDING SEASON. A RELATIVELY HIGH PREGNANCY RATE WAS OBTAINED FOLLOWING THE TRANSFER OF FRESH EMBRYOS. HOWEVER, THE SURVIVAL RATE OF EMBRYOS FOLLOWING EITHER FRESH, SLOW FROZEN-THAWED OR VITRIFIEDTHAWED EMBRYOS WAS UNSATISFACTORY. MORE RESEARCH IS THUS WARRANTED, WITH A HIGHER NUMBER OF ANIMALS, DIRECTED AT IMPROVING THE SURVIVABILITY OF EMBRYOS FOLLOWING FRESH AND CRYOPRESERVED GOAT EMBRYO TRANSFER. THE FOURTH TRIAL WAS CONDUCTED DURING THE NATURAL BREEDING (AUTUMN, 2007). DONOR DOES WERE SUPEROVULATED FOLLOWING A LONG (17 DAY) PROGESTAGEN SYNCHRONISATION PROTOCOL, WITH OR WITHOUT PROSTAGLANDIN-F2Î OR SUPEROVULATED FOLLOWING A PREDETERMINED TIME OF OVULATION (DAY 0 PROTOCOL). RECIPIENT DOES RECEIVED FROZEN-THAWED OR FRESH BOER GOAT EMBRYOS FOLLOWING OESTROUS SYNCHRONISATION USING DIFFERENT PROTOCOLS. DURING THE SYNCHRONISATION TREATMENT PRIOR TO SUPEROVULATION ONLY 71.4% OF THE DOES IN THE DAY 0 PROTOCOL EXHIBITED SIGNS OF OESTRUS, WHILE ONLY ONE DOE EXHIBITED SIGNS OF OESTRUS FOLLOWING SUPEROVULATION. ALL DOES SHOWED OVERT SIGNS OF OESTRUS FOLLOWING LONG PROGESTAGEN TREATMENT WITH OR WITHOUT ADMINISTRATION OF PROSTAGLANDIN-F2Î. ALL DOES ALSO DEMONSTRATED A SIMILAR RESPONSE TIME FROM CIDR REMOVAL TO THE ONSET OF OESTRUS AND THE DURATION OF THE INDUCED OESTROUS PERIOD. THE DAY 0 PROTOCOL RESULTED INTO A SIGNIFICANTLY (P<0.01) LOWER TOTAL NUMBER OF CLâS (4.0±3.5) PER DOE - COMPARED TO GROUP 2 (17-DAY PROGESTAGEN TREATMENT PLUS PGF2Î) (14.5±4.6) AND GROUP 3 (17-DAY PROGESTAGEN TREATMENT) (16.5±5.9). THE MEAN NUMBER OF STRUCTURES RECOVERED FROM GROUP 1 (1.4±0.5) WAS SIGNIFICANTLY (P<0.05) LOWER, COMPARED TO GROUP 3 (11.4±7.3). THIS MEAN IN THE DAY 0 GROUP HOWEVER DID NOT DIFFER SIGNIFICANTLY, WHEN COMPARED TO GROUP 2 (8.4±7.7). THE VARIATION RECORDED BETWEEN ANIMALS IN THE GROUP 2 WAS VERY HIGH. THE DAY 0 PROTOCOL RESULTED IN A SIGNIFICANTLY (P<0.01) LOWER MEAN NUMBER OF EMBRYOS BEING RECORDED. HOWEVER, THE MEAN NUMBER OF UNFERTILISED OVA AND DEGENERATING EMBRYOS WAS SIMILAR FOR ALL THE TREATMENT GROUPS. THE DAY 0 (GROUP 1) GROUP RESULTED IN THE COLLECTION OF ONLY ONE EMBRYO, WHICH WAS ALSO TRANSFERABLE, BUT DUE TO THE SINGLE VALUE THIS DATA WAS NOT ANALYSED. THE ADDITION OF PROSTAGLANDIN-F2Î HAD NO EFFECT ON THE FERTILISATION RATE AND THE MEAN NUMBER OF TRANSFERABLE EMBRYOS RECORDED BETWEEN GROUP 2 AND 3. THE TIME INTERVAL FROM CIDR REMOVAL TO THE ONSET OF OESTRUS IN THE ADULT DOES WAS SIGNIFICANTLY (P<0.01) SHORTER THAN THAT RECORDED IN THE YOUNG DOES. HOWEVER, AGE DID NOT HAVE ANY SIGNIFICANT EFFECT ON THE DURATION OF THE INDUCED OESTROUS PERIOD. THE MEAN NUMBER OF CLâS, STRUCTURES AND EMBRYOS RECOVERED WERE HOWEVER SIGNIFICANTLY (P<0.01) HIGHER IN THE ADULT DOES. NO RECOVERY OF UNFERTILISED OVA WAS RECORDED IN THE YOUNG DOES AND THE FERTILISATION RATE AND MEAN NUMBER OF UNFERTILISED OVA DID NOT DIFFER BETWEEN THE YOUNG AND ADULT DOES. SIMILARLY THE AGE OF THE DOE HAD NO EFFECT ON THE MEAN NUMBER OF DEGENERATE EMBRYOS PER DONOR RECORDED. THE MEAN NUMBER OF TRANSFERABLE EMBRYOS PRODUCED IN THE ADULT DOES (15.8±6.4) WAS SIGNIFICANTLY (P<0.01) HIGHER, THAN IN THE YOUNG DOES (9.5±3.7). THE TIME FROM CIDR REMOVAL TO THE ONSET OF OESTRUS WAS NOT AFFECTED BY REPEATED SUPEROVULATION TREATMENT. DOES SUPEROVULATED FOR THE FIRST TIME SHOWED A SIGNIFICANTLY (P<0.05) SHORTER MEAN DURATION OF OESTRUS (20.8±10.1H), WHEN COMPARED TO THOSE REPEATEDLY SUPEROVULATED (30.4±6.7 H). REPEATED SUPEROVULATION DID NOT SHOW AN EFFECT ON THE TOTAL NUMBER OF CLâS PRODUCED PER DOE. HOWEVER, THE MEAN NUMBER OF STRUCTURES RECOVERED WAS SIGNIFICANTLY (P<0.05) LOWER IN THE REPEAT-TREATED DOES (6.0±8.7), COMPARED TO DOES SUPEROVULATED FOR THE FIRST TIME (11.7±5.0). SIMILARLY, THE MEAN NUMBER OF EMBRYOS RECOVERED PER DOE WAS SIGNIFICANTLY (P<0.05) HIGHER IN DOES SUPEROVULATED FOR THE FIRST TIME. THE MEAN NUMBER OF UNFERTILISED OVA PER DONOR WAS ALSO SIGNIFICANTLY (P<0.05) HIGHER IN THE REPEATEDLY-TREATED DOES (5.5±7.8), COMPARED TO THE 0.1±0.3 FOR DOES SUPEROVULATED FOR THE FIRST TIME. THIS RESULTED IN A SIGNIFICANTLY (P<0.05) LOWER FERTILISATION RATE BEING OBTAINED IN THE REPEATEDLY-TREATED DOES (50.0±70.7%), COMPARED TO DOES SUPEROVULATED FOR THE FIRST TIME (99.4±1.9%). THE MEAN NUMBER OF DEGENERATE EMBRYOS DID NOT DIFFER SIGNIFICANTLY BETWEEN THESE GROUPS. THE NUMBER OF TRANSFERABLE EMBRYOS RECORDED WAS SIGNIFICANTLY (P<0.05) LOWER IN THE REPEATEDLY TREATED DOES (3.8±8.5), COMPARED TO THEIR COUNTERPARTS (10.7±4.0). IN GROUP A (CIDR + PGF2Î + ECG; CHRONOGEST) 88.9% OF THE DOES RESPONDED TO OESTROUS SYNCHRONISATION. ALL DOES IN GROUP B (CIDR +ECG; FOLLIGON) AND GROUP C (CIDR + ECG; CHRONOGEST) EXHIBITED SIGNS OF OESTRUS FOLLOWING OESTROUS SYNCHRONISATION. DOES FROM GROUP A (42.0±3.7 H) EXHIBITED A LONGER (P<0.05) TIME INTERVAL FROM CIDR WITHDRAWAL TO THE ONSET OF OESTRUS, COMPARED TO GROUP C DOES (32.0±8.6H). THERE WAS HOWEVER, NO SIGNIFICANT DIFFERENCE WITH RESPECT TO THE TIME INTERVAL FROM CIDR REMOVAL TO THE ONSET OF OESTRUS BETWEEN GROUP A AND B. GROUP B AND C DOES ALSO RECORDED A SIMILAR RESPONSE TIME FROM CIDR WITHDRAWAL TO THE ONSET OF OESTRUS. THE DURATION OF THE INDUCED OESTROUS PERIOD BEING SIGNIFICANTLY (P<0.05) SHORTER IN GROUP B (19.0±13.5H), WHEN COMPARED TO GROUP A (39.0±15.1H). NO SIGNIFICANT DIFFERENCE WAS RECORDED BETWEEN GROUP B AND C REGARDING THE DURATION OF THE INDUCED OESTROUS PERIOD. IT COULD THUS BE CONCLUDED THAT THE POOR OVARIAN RESPONSE TO THE SUPEROVULATORY TREATMENT IN THE GROUP 1 (DAY 0 PROTOCOL) WARRANTS FURTHER RESEARCH WHICH WILL HAVE TO FOCUS ON THE SYNCHRONISATION OF OVULATION AND AN APPROPRIATE TIME FOR INITIATING A SUPEROVULATORY TREATMENT IN THIS PROTOCOL. THE ADDITION OF A PROSTAGLANDIN-F2Î TREATMENT IN THE SUPEROVULATORY PROTOCOL FOLLOWING A LONG PROGESTAGEN SYNCHRONISATION TREATMENT IN BOER GOAT DOES ALSO HAS NO REAL ADVANTAGE. THE TIME OF PROSTAGLANDIN ADMINISTRATION AND THE DOSAGE USED COULD HAVE CONTRIBUTED TO THE OBSERVED RESULTS. THE AGE OF THE DONOR DOE HAS BEEN SHOWN TO HAVE A MAJOR EFFECT ON THE OVARIAN ACTIVITY FOLLOWING SUPEROVULATION TREATMENT. ALTHOUGH THE YOUNG DOES RECORDED AN ACCEPTABLE FERTILISATION RATE, THE NUMBER OF TRANSFERABLE EMBRYOS WAS HOWEVER LOWER. THEREFORE, IF A LARGE NUMBER OF ACCEPTABLE EMBRYOS (THE MAXIMUM) ARE REQUIRED IN A MOET PROGRAMME, IT IS MORE APPROPRIATE TO SUPEROVULATE MULTIPAROUS MATURE GOATS. THIS WILL LEAD TO THE PRODUCTION OF MORE TRANSFERABLE EMBRYOS. THE NUMBER OF TIMES THAT A DONOR CAN BE UTILISED IN A BOER GOAT MOET PROGRAMME SEEM IS TO BE LIMITED TO THREE TIMES DUE TO REDUCTION IN THE NUMBER OF STRUCTURES AND EMBRYOS BEING RECOVERED FROM THE 4TH TIME REPEATEDLY TREATED DOES. MOREOVER, THE NUMBER OF UNFERTILISED OVA INCREASED FOLLOWING REPEATED SUPEROVULATION, HENCE REDUCING THE FERTILISATION RATE AND EVENTUALLY THE NUMBER OF TRANSFERABLE EMBRYOS. THE THREE PROTOCOLS USED FOR OESTROUS SYNCHRONISATION IN RECIPIENTS WERE EFFICIENT IN SYNCHRONISING OESTRUS. THE PREGNANCY RATE OBTAINED WAS GENERALLY LOW IN ALL THE TREATMENT GROUPS AND POSSIBLE INTERACTIONS THUS COMPLICATE THE MAKING OF ANY DEFINITE RECOMMENDATIONS.

The fencing of small areas and stocking them with game species is becoming a common tendency in South Africa. The main objective of this study, conducted during the 2003/04 and 2004/05 seasons in a small fenced in game enclosure (78 ha) in the Bloemfontein district, Free State Province, was to determine the small-scale habitat and feeding preferences of springbok (Antidorcas marsupialis), blesbok (Damaliscus pygargus phillipsi) and black wildebeest (Connochaetes gnou) within the same vegetation type. The associations between soil, vegetation and grazing time by these herbivore game species were also determined, as well as whether the simulated influence of Type I herbivores on the sward structure will affect the small-scale habitat preferences of these herbivore species, which are all regarded as Type III species. A relatively homogeneous area of 250 x 200 m (5 ha) in the middle of an open grassland area was selected for intensive study. The selected area was subdivided into twenty experimental plots of 50 x 50 m (0.25 ha), which were permanently marked and allocated an identification code. Analysis of the soil was done to assess the physical properties, ionic content and electrical resistance of the soil in each experimental plot. Plots varied considerably in terms of the chemical content of the soil, which was largely influenced by soil texture. This may account for the heterogeneity of the vegetation of the demarcated area. Prior land use and small-scale variation could also have influenced the soil quality and vegetation. The botanical composition of the herbaceous layer was determined using a wheel point apparatus according to the nearest plant method, based on occurrence. Surveys were done at the end of each growing season (2003/04 & 2004/05). Above-ground dry matter production was determined by harvesting all plants in 20 randomly-selected 0.25 m² quadrates within each experimental plot, and weighing them. Plots on the northern side had a lower number of grass species with a lower grazing value (predominantly Increaser species), while plots on the southern side had a higher number of grass species with a higher grazing value (predominantly Decreaser species). Changes in the botanical composition between the two seasons (an increase in Increaser species) and the decrease in veld condition scores suggest that the veld is over-utilised and in a poor condition, and that stocking rates are currently too high. However, veld in this condition is the preferred habitat of short grass grazers. Therefore, a compromise between short grazing (habitat suitability) and veld in a good ecological condition seems to be the proper approach. The small-scale spatial preferences of the three herbivore game species were studied by making observations, using binoculars, from a parked vehicle during the morning and afternoon. Both springbok and blesbok preferred habitat patches with a high abundance of Increaser species, relatively high species diversity and moderate to low veld condition score. Black wildebeest tended to favour patches with a higher occurrence of Decreaser species, although Increaser species were also relatively abundant in these plots. The preferred experimental plots generally had a low above-ground DM production. The number of habitat patches utilised was highest during the dry season. A modification of the grazed-class method was used to determine the favoured grass species and percentage utilisation during the different seasons. Marked plants were inspected weekly from June 2004 to May 2005, and subjective estimates were given for utilisation using a developed field reference guide. Themeda triandra, Eragrostis obtusa, Panicum stapfianum, E. plana and Digitaria eriantha were the favoured grass species of springbok, blesbok and black wildebeest. Less-favoured species included Brachiaria eruciformis, Cynodon dactylon, E. chloromelas and Setaria incrassata, while non-favoured species included Tragus berteronianus, Aristida bipartita and Cymbopogon pospischilii. Seasonal variation in utilisation was demonstrated, with a larger number of species that were utilised during the rainy season. Associations between soils, the herbaceous layer and time spent grazing indicated that soil texture, and degradation due to over utilisation, were the most important factors that caused spatial variation in the botanical composition of the grassland area. Less-favoured and nonfavoured grass species mainly occurred on heavy clay soil and were closely associated with soil Na, Ca, Mg and K. In contrast, favoured grass species mostly occurred on soil with higher sand and silt content and were closely associated with soil N, C and Zn. Time spent grazing by springbok, blesbok and black wildebeest were closely associated with the favoured grass species (as listed above). To determine the influence of the simulated effect of Type I species on the small-scale habitat preferences, the grass was mown in two plots with a lawnmower at a height of 5 cm, and in another two plots at a height of 15 cm. Each cutting treatment consisted of a plot containing palatable and unpalatable grass species. Observations were conducted as described previously. The simulated influence of Type I species on the sward structure (grass mown at 5cm) of underutilised grassland may facilitate the occupation of such grassland by short grass grazers, particularly blesbok, which previously avoided these areas. Generally, no distinctive changes in the activity of springbok and black wildebeest could be found. It is recommended that stocking rates in the game enclosure be reduced and maintained at sustainable levels to allow the vegetation to recover and reduce further degradation. Continual assessment of the vegetation is essential to monitor further changes in the herbaceous layer and evaluate long-term sustainability of the game enclosure. Similar monitoring is recommended for all small fenced game ranches.

1. The purpose of the first chapter was to give a short introduction to the study. Although there were exponential increases in knowledge, there are still fields of study where there is little understanding and enormous gaps relating to information. A short history of the development of cattle was presented, with special reference to the Simmentaler breed. The objectives of this study were then stated. These objectives were: the definition of breeding objectives, derivation of economic values and development of economic selection indices for the Simmentaler breed in South Africa. 2. In Chapter 2 the development of breeding objectives and the derivation of economic values were reviewed. There seems to be general consensus that definition of breeding objectives should be the primary step in the design of structured breeding programs. Development of the breeding objective can be described in terms of the following phases: specific ation of the breeding, production and marketing system, identification of sources of income and expense in commercial herds, determination of biological traits that influence income and expense, derivation of economic values, choice of selection criteria, and estimation of phenotypic and genetic parameters. The modeling methods to derive economic values can be divided into simulation, dynamic programming and profit functions. 3. In Chapter 3 the important traits, which should be considered for the development of breeding objectives, as well as the criteria to be included in the selection index were reviewed. Traits were classified as fitness-, production-, product-, input-, type- and behavioural traits. The decision whether or not to include a trait in the breeding objective depends on the relative economic value of the trait, the potential for genetic improvement and the possibility of accurate and cheap measurement. Several traits determine economic efficiency, and the required balance of these traits is likely to differ between different production systems. 4. The purpose of Chapter 4 was the development of a general breeding objective for the Simmentaler breed in Southern Africa as well as the derivation of economic values for beef production traits. Income was partitioned between weaners (steers), surplus heifers and cull cows. Expenses were calculated for all classes and included feed cost, husbandry cost and marketing cost. Economic values for weaning weight (direct), weaning weight (maternal), yearling weight (400 days), final weight (600 days) and mature cow weight were derived as partial derivatives of the profit equation. These values, expressed per genetic standard deviation, in South African Rand per cow, corrected with the discounted gene flow and diffusion coefficient methods (in brackets) are, 25.57 (75.01), 15.21 (47.97), 28.49(83.63), -13.95 (-40.79) and -69.29 (-63.39) respectively. 5. The objectives of Chapter 5 were to expand the Simmentaler breeding objective by inclusion of functional traits and to derive economic values for the functional traits calving rate, days -to-calving, calving-ease (direct) and calving-ease (maternal). It was assumed, for these categorical traits, that there is an unobserved underlying normal distribution of the sum of genetic and environmental values, and that the phenotypic category is defined by threshold values on this distribution. The consequences of a change in fitness included changes in costs, changes in culling rate, number of barren cows and the number of surplus offspring available for sale. Results emphasised the relative importance of fertility. Economic values, expressed per genetic standard deviation in South African Rand per cow, corrected with the discounted gene flow and diffusion coeffic ient methods (in brackets) are, 18.98 (15.27), - 93.82 (- 75.51), 1.08 (1.31) and 1.15 (1.08) for calving rate, days-to-calving, calving-ease (direct) and calving-ease (maternal), respectively. 6. The objectives of Chapter 6 were to expand the Simmentaler breeding objective by the inclusion of product quality traits and to derive economic values for dressing percentage, backfat thickness, tenderness and marbling. A method to derive economic values for these optimum traits was described. It was as sumed, for the categorical traits, that there is an unobserved underlying normal distribution of the sum of genetic and environmental values, and that the phenotypic category is defined by threshold values on this distribution. The consequences of a change in the mean performance of a trait include changes in the number of animals in different quality classes and as a result thereof, changes in the expected value of a carcass. Economic values, expressed per genetic standard deviation in South African Rand per cow, corrected with the discounted gene flow and diffusion coefficient methods (in brackets) are, 20.96 (61.50), 0.39 (1.14), -3.52 (-10.33) and 0.18 ( 0.52) for dressing percentage, backfat thickness, tenderness and marbling respectively. 7. The development of economic selection indices for an integrated Simmentaler production system was described in Chapter 7. The breeding objective was defined in terms of production-, functional- and product quality traits. Criteria included in the total index are birth- and weaning weight (direct and maternal), yearling weight, final weight, mature cow weight, days -to-calving, backfat thickness, tenderness and marbling. The total merit index (IT) for an integrated Simmentaler production system is IT = â 1.65 BWD â 1.99 BWM + 2.28 WWD + 1.76 WWM + 1.48YW â 0.50 FW â 2.02 MCW â 13.21 CD + 4.92 BF â 2.34 T + 12.77 M. The correlation between this index and the breeding objective is 0.987. The economic superiority, over the average progeny, of the progeny from the top 40% of animals selected on their ranking in the total index, is expected to be R116.49.

Studies were made on growth, carcass and egg performance as well as mortality of the Lesotho native chickens compared to the South African native (Potchefstroom Koekoek, Ovambo, Lebowa-Venda and Naked Neck) and two exotic lines, namely the New Hampshire a nd Rhode Island Red from 3-days old to 70 weeks old (moulting). Chickens were raised in two batches with an interval of four weeks between the two batches: from 3-day old to ten and six in Batches 1 and 2, respectively. Chickens were reared in Bloemfontein (UFS) under confinement, fed ad libitum with broiler starter mash for the first four weeks where after grower mash was fed to the chickens up to the age of ten weeks old. From this stage until the end of the laying phase, they were all fed yellow maize and managed semi-intensively in Lesotho at the NULFOA. The study was done in two phases, namely the pre-laying and laying phases. With the exception of feed conversion ratio (FCR), which was conducted in the first 35 days of the study, all measurements of growth and egg performance traits were recorded weekly while mortality was recorded daily. Carcass yield analysis was done at 70 weeks of age. Presentation of the growth data was done in three stages, namely 3-day, 26-week and 70-week weights, which are considered crucial in a chickenâs life span. The means of the Lesotho line were significantly different (p<0.05) from other lines in all growth traits, namely 3-day weight, 26-week weight, average daily gain (ADG) and average weekly gain (AWG) except for the FCR and hen weight at 70 weeks old. With the exception of the New Hampshire and Potchefstroom Koekoek, no significant differences (p>0.05) were observed between the Lesotho hen weight and other lines. The Ovambo had the highest body weight and avera ge daily gain of all the native populations at 26-weeks old, while the Potchefstroom Koekoek had the highest 70-week weight. Feed conversion ratios ranged between 3.2±1.9 for the New Hampshire to 3.9±1.2 for Naked Necks in Batch 1, and 3.3±1.2 for New Hampshire to 4.2±0.9 for the Lesotho line in Batch 2. All differences between the lines for FCR were highly significant (p<0.01). All the lines commenced their egg production between the 25th to 26th weeks of age and there were no significant differences (p> 0.05) between the ages at first lay among all the lines. Egg production was found to differ significantly (p<0.05) among the different lines. The average number of eggs laid per week per hen and egg weight of the Lesotho hens was 1.2 and 48.5g, respectively. The New Hampshire had a significantly (p<0.05) higher dressed weight than other lines (1903.0±190.8g) while the Naked Neck had the lowest (1297.7±133.0g). Bone and head weight were not significantly different (p>0.05) among the different lines. The Lesotho line had the highest overall mortality (89%) of all the lines. The lowest mortality (27%) was found in the Potchefstroom Koekoek. A probable reason for high mortalities in the Lesotho could be ascribed to the result of inbreeding within the line. Although the Lesotho hens exhibited the lowest growth at the onset of laying (1113.8±71.6g), they eventually compensated and ended being large (2047.5±65.6g) at 70-weeks old. The Lesotho hen, like the New Hampshire and Potchefstroom Koekoek showed potential for being a good dual-purpose breed, since it was able to maintain a high body weight at the end of laying. Therefore the breed has an advantage of fetching a higher market price at the end of laying. The constraint is that of their low growth in the earlier part of their life span. This can be improved through the implementation of planned breeding programs.

The present study was carried out to estimate genetic, phenotypic and environmental parameters for growth traits, genetic trends as well as the level of inbreeding in the South African Brahman breed. The data used were obtained from the South African Brahman Breedersâ Society and consisted of pedigree information of 181 508 animals and 221 015 performance records, ranging from birth to 18-months weight /final weight collected between 1955 and 2002. Performance records available before editing as classified according to age ranges were birth weight (BWT) = 67 336, weaning weight (WWT) (80â300 days) = 62 159, yearling weight (YWT) (301-500 days) = 41 313 and final weight (FWT) (501-900 days) = 32 602. The linear animal model used included the fixed effects of contemporary group (herd-year-season), sex, management group, age of the calf, age of the dam. Direct genetic, maternal genetic and permanent maternal environmental as random effects as well as sire x herd-year-season interaction as an additional random effect. Preliminary analyses showed that all fixed effects had a significant (P<0.0001) effect on all traits studied. Genetic parameters for growth traits were estimated using ASREML software by fitting univariate and bivariate animal models. Production traits considered after editing were BWT = 41 509, WWT = 37 705, YWT = 22 682 and FWT = 13 055 records collected between 1985 and 2002. The reason for using the data only from 1985 is that only a small number of records were recorded up to 1984. The direct heritability estimates of BWT, WWT, YWT and FWT were 0.28, 0.14, 0.14 and 0.18 respectively. The corresponding maternal heritability estimates were 0.11, 0.06, 0.05 and 0.03 respectively. The maternal permanent environmental component due to the dam contributed 3 - 7 % of the total phenotypic variance of the traits under consideration. The corresponding contribution of sire x herd-year-season interaction ranges from 5 - 6%. The genetic correlation between animal effects was -0.36 for BWT, other traits studied did not show an antagonism between animal effects. The prospects of improvements of these traits by selection seem possible and the contributions of permanent maternal environmental effect are not equally important as maternal effects though the effects are small. Estimates of phenotypic correlations were low to moderate (0.22 to 0.64), whereas genetic correlations were moderate to high (0.47 to 0.91). Genetic correlations between BWT and WWT, YWT and FWT were 0.62, 0.47, and 0.52 respectively. The corresponding genetic correlations between direct and maternal effects of the same trait (ram, rma) were (-0.4204, -0.014), (-0.4241, 0.0567) and (0.05170, 0.0879) respectively. Genetic correlations between WWT and postweaning weights were 0.88 and 0.91 for YWT and FWT respectively. The corresponding maternal correlation was at unity. Lastly, the genetic and maternal correlation between YWT and FWT were 0.83 and unity, respectively. Positive genetic trends were observed for all traits except for the maternal genetic trend for BWT, which had a slightly negative slope. Direct genetic progress for BWT was 0.0207 kg/year (1987-2002), whereas progress for WWT was 0.1kg/year (1985-1995) and 0.4 kg /year (1996-2001). Progression in direct genetic effect for YWT was 0.1kg/year (1985- 1995) and 0.3 kg/year (1996-2001) whereas progress for FWT was 0.13 kg/year (1985-2001). The maternal genetic trends were -0.003, 0.04, 0.008 and 0.003 kg/year for BWT, WWT, YWT and FWT, respectively. Genetic progress was in general low over the years for all traits. Therefore, estimation based on BLUP of breeding values may be more important in the future and should be considered to maximise opportunities for genetic change. Inbreeding level and its possible influence on growth traits of the South African Brahman cattle were investigated. Inbreeding coefficients were calculated by inverting the diagonal of the inverse relationship matrix using the MTDFNRM program of the MTDFREML package. Inbreeding depression was estimated as the regression of performance on individual and dam inbreeding coefficients using an animal model. The mean inbreeding of the population was very low (0.01) with an average of (0.03) for inbred animals. Although regression coefficients of BWT, WWT, YWT and FWT on inbreeding of animal and dam were significant for all traits, the results showed that inbreeding at present is not a serious problem in the South African Brahman breed.

A study was conducted to investigate the influence of different particle sizes of a specific amorphous limestone source (calcium carbonate) in a layer diet on egg production and egg quality at peak production (week 24). Ninety nine layer pullets, 17 weeks old, were obtained from a commercial layer breeder. The pullets were randomly allocated to three groups. All the pullets received the same layer diet. The only differences among the treatment groups were that the pullets in each group received one of the three different particle sizes in the diet namely:- (a) Less than 1.0 millimetre (b) 1.0 and 2.0 millimetre (c) 2.0 and 3.8 millimetre The influence of the three particle sizes on the feed intake, body weight and egg production as well as egg characteristics was recorded. The average weekly feed intake, body weight and egg production of layers from week 18 up to 28 were not (P> 0.05) different among the layer diets with the different particle sizes. The particle size of limestone in the layer diets did not influence egg weight (P= 0.2159) and egg output (P=0.2388) significantly at peak production. Average egg weight tended (P= 0.2159) to be heavier when coarse particles were fed. No statistic al significant (P> 0.05) differences in egg volume, egg contents, egg surface area, shell weight per unit surface area, shell percentage and shell thickness occurred. According to these results limestone particle size in layer diets has no influence on eggshell quality. In the second study the effect of particle size distribution of a specific limestone source in layer diet on egg production and egg quality at peak production (week 24) was investigated. One hundred and sixty seven layer pullets , 17 weeks old, were obtained from a commercial layer breeder. The pullets were randomly allocated to five groups. All the pullets received the same layer diet. The only differences among the treatment groups were that the pullets in each group received one of five different ratios of fine (less than 1.0 mm) and coarse (between 2.0 and 3.8 mm) limestone particle size namely 100, 75, 50, 25 and 0 % fine or coarse. The influence of the five dietary limestone particle size distributions on the feed intake, body weight, and egg production of layers as well as egg characteristics mentioned in the first study were investigated. No significant (P> 0.05) influence of dietary limestone particle size distribution was found on feed intake, body weight and egg production of layers. Accordingly no significant differences occurred in egg volume, (P= 0.1310) and egg surface area (P= 0.1393). The highest (P< 0.001) egg contents were recorded where 100 and 75% fine limestone particles were included in the diet. Although significant differences for shell weight (P<0.0017) and shell percentage (P<0.0001) occurred, no clear influence of particle size distribution on these characteristics could be detected. In accordance wit h shell weight per unit surface area no significant differences (P> 0.05) in eggshell thickness occurred. It was concluded that different dietary limestone particle sizes and distributions have no influence on eggshell quality at peak production (week 24). The influence of dietary limestone particle size and distribution during the later stages of the laying period on bone formation and egg quality needs further investigation.

1. A study was conducted to investigate the effects of dietary Ca levels and feed restriction on the bone development of broiler breeder pullets up to 18 weeks of age. Six hundred and forty one-day-old Ross breeder pullets were randomly assigned to 4 treatment groups; namely 1.0% Ca (0.45% Pi), 1.5% Ca (0.7% Pi), 2.0% Ca (0.9% Pi) and 1.0% Ca (0.45% Pi). The first three treatments were feed restricted while the last treatment was fed ad lib. At 6, 12 and 18 weeks of age 20 pullets were randomly selected from each treatment and killed. Treatment effects on bone dimensions (length, width and weight), bone ash, Ca and P contents of tibia, mechanical properties (bone strength and stress) were investigated. Increasing dieta ry Ca levels had no significant (P>0.05) effect on bone measurements. As expected, all the bone measurements significantly (P<0.05) increased with age. Feed restriction significantly (P<0.05) reduced all the bone characteristics. The results suggested that 1.0% Ca (average 0.7 g/hen/day) is sufficient to support bone development and growth for feed restricted broiler breeder pullets up to 18 weeks of age. 2. One hundred and ninety eight Ross broiler breeder pullets were reared on restricted diets with 1.0, 1.5 and 2.0% Ca up to 22 weeks of age. The pullets in each experimental diet were further randomly divided into three treatments with 1.5, 2.5 and 3.5% dietary Ca (66 birds per treatment) fed from 23 to 60 weeks. At 35 and 60 weeks of age, 12 pullets per treatment were randomly selected and killed to obtain tibiae and humeri. Treatment effects on bone dimensions, bone ash, Ca and P content of tibia, mechanical properties, true cortical area (TCA) and percent bone were investigated. The 1.5% Ca diet resulte d in lower (P<.05) feed intake and body weight. Calcium level had no effect on bone dimensions, bone stress, ash content, Ca content of ash, TCA and percent bone. These results suggest that the 2.5% dietary Ca (4 g/hen/day) may be adequate to support bone development and growth of feed restricted broiler breeder pullets. 3. The broiler breeder pullets described in paragraph 2 were used to investigate the effects of three levels of dietary Ca (1.5, 2.5 and 3.5%) during the early lay period (23 to 35 weeks) on egg production and eggshell quality. Increasing dietary Ca level from 1.5 to 3.5% had no significant effect (P>.05) on egg production, egg weight, egg mass, egg surface area and egg contents. Increasing the level of Ca from 1.5 to 2.5% increased shell weight, shell weight per unit surface area, shell percentage and shell thickness. As anticipated, egg weight increased with age. The converse was true for egg production and eggshell parameters. It was concluded that a dietary Ca level of 2.5% and Ca intakes of 3.8, 3.9, and 3.5 g at weeks 27, 30 and 33, respectively were sufficient to sustain good eggshell quality of feed restricted broiler breeder hens. 4. The mentioned broiler breeder hens in paragraph 3 were fed three dietary Ca levels, 1.5, 2.5 and 3.5% from week 36 to 60. Regression analysis suggested that Ca level during the rearing period could positively influence eggshell quality during the later stages of lay (36 to 60 weeks). Increasing dietary Ca level from 1.5 to 2.5% during the laying period significantly (P<.05) increased egg production, egg weight, egg mass, shell weight, egg contents, egg surface area, shell percentage, shell weight per unit surface area and shell thickness. As anticipated, egg weight, shell weight, egg contents and egg surface area increased with age while egg production, egg mass, shell percentage and shell thickness declined. These results suggest that the 2.5% Ca (3.8 g/hen/day) is adequate to support egg production and to improve eggshell quality in feed restricted broiler breeder hens. 5. The effect of dietary Ca intake (1.5, 2.5 and 3.5% dietary Ca) on Ca retention of broiler breeder hens (30 per treatment) and the relationship between Ca retention and egg characteristics was investigated. Shell (r=0.27) and faecal (r=0.50) Ca excretions were significantly (P<.05) positively related to Ca intake of broiler breeders. Proportionally less of the Ca intake was used for eggshell formation as the intake of broiler breeders increased. It seems that a higher Ca intake was mainly accompanied by a higher Ca excretion through the faeces. The net effect of Ca intake and total Ca excretion was that the 2.5% Ca level (3.8 g Ca /hen/day) exhibit a significant (P<.05) higher Ca retention compared to 1.5% Ca. It was concluded from the results that 1.0% dietary Ca (0.7 g /pullet/day) is needed during the rearing period up to 22 weeks. Thereafter 2.5% Ca (3.5 to 4.0 g /hen/day) should be included in broiler breeder diets up to 60 weeks. The possible effect of Ca levels during the rearing period on eggshell quality needs further investigation.

This study was carried out to generate information on village based indigenous chicken utilization, management practices, opportunities and challenges, to identify, characterize and describe the phenotypic variation of indigenous chicken populations. The study was also aimed to provide preliminary data on the genetic variation of indigenous chicken populations using microsatellite markers and to compare and evaluate the growth, egg production, reproductive performances, as well as the rate of survival of indigenous chickens under intensive and extensive management levels. Surveys using both purposive and random sampling methods were carried out in four zones of Northwest Ethiopia to describe the village-based poultry production systems and constraints in order to design future improvement and conservation strategies. The result of this study showed that the majority of the respondents were female (74.16 %). This indicated that most of the time the women, whether in male-headed or female-headed households are responsible for chicken rearing, while the men are responsible for crop cultivation and other off-farm activities. About 99% of the respondents gave supplementary feeds to their chickens. Night shelter was provided by almost all farmers in a part of the kitchen (1.36 %) or in the main house (39.07 %), in handwoven baskets (7.29 %), in bamboo cages (1.51 %) or in a separate shed purpose-made for chickens (50.77 %). The major causes of death of chickens during the study were seasonal outbreaks of Newcastle disease (locally known as âfengeleâ) and predation. It is important to collect and conserve local poultry breeds before they are fully replaced by the so-called improved exotic chicken breeds. As most of the poultry production is managed by women, focusing on training and education of women will aid not only the improvement of poultry production but also family management, family planning and the overall living standards of the family and the community. In the phenotypic characterization, a total of three hundred chickens were characterized under field conditions for qualitative and quantitative traits following standard chicken descriptors. Seven distinct indigenous chicken populations from four administrative zones were identified. Large phenotypic variability among chicken populations was observed for plumage colour. About 25.49 %, 22.30 %, and 16.40 % of the chickens have white, grayish and red plumage colours, respectively. The rest showed a considerable heterogeneity regarding plumage colours, like black, multicoloured, black with white tips, reddish brown and white with red stripes. The following characteristics were also displayed: plain heads (51.18 %), yellow shanks (64.42 %), and pea comb (50.72 %). About 97.52 % of the chickens did not have feathers on their legs. Variations were also observed in quantitative characteristics such as shank length, egg size and body weight and other reproductive traits exhibited in an intensive management system. In the genetic analysis, indigenous chicken populations representing seven different areas of Northwest Ethiopia were studied using microsatellite markers to determine genetic diversity and relatedness. Three South African chicken lines and two commercial chicken (RIR and WLH) breeds were included for control. A high genetic diversity was observed overall loci and populations with a heterozygosity value of 0.76. The largest heterozygosity (0.93) across all markers was observed in the Mecha chicken population, while the smallest heterozygosity across all loci (0.66) was observed in the White Leghorn breed. A higher genetic distance (lower genetic similarity) between the RIR commercial chicken breed and the Ethiopian indigenous chicken populations were observed compared to RIR and South African fowls. This indicates that the Ethiopian indigenous chicken populations have still not been highly diluted by the RIR commercial chicken breed either through the extension program or through the regional poultry breeding and multiplication institutes. The present result indicated that the clustering of the chicken populations is in accordance with their geographical origin and market places. Microsatellite markers used in this study were found suitable for the measurement of the genetic variation in Ethiopian chicken populations. These results can therefore serve as an initial step to plan the characterization and conservation of indigenous chickens in the Amhara region, Ethiopia. A study on the performance of indigenous chicken populations in terms of growth, carcass yield, egg production and egg quality was evaluated under intensive management conditions compared with the RIR commercial breed. Significant differences were observed among the indigenous chicken genotypes of Northwest Ethiopia for body weight, feed intake, FCR, mortality percentage at different phases of growth, indicating the phenotypic variations of the different chicken ecotypes. The Mecha chickens had the highest growth rate, followed by Guangua and Melo- Hamusit chickens, indicating that these lines are good for meat production. Analysis of carcass characteristics has shown that most of the male and female finisher grower chickens have a higher dressing percentage than the commercial RIR chicken breed managed under intensive management. Furthermore, data on age at point of lay (days) indicated that indigenous chickens reached the first egg production stage from 144 to 168 days, while the RIR breed started producing eggs at 150 days. In general, the current result indicates that the performance of the indigenous chickens is comparable with the RIR breed under intensive management systems. This indicates that there is a chance for better performance if proper selection and breeding plan are designed for indigenous chickens.

This study made use of the opportunity provided by fenceline contrasts in Namibia to measure differences in rangeland and learn from farmers about the inputs and outputs of management on each side of the fence. The 34 measured contrasts were mostly clustered within the Camelthorn and Thornbush Savannas, with three in the Highland and Dwarf shrub Savannas of Namibia. Mean annual rainfall ranges from 235 to 475 mm. Rangeland measurements focussed on well established perennial vegetation to avoid the fluctuating effect of ephemerals. Eight characteristics were measured and significant (P<0.05) differences occurred in at least one of these at each contrast. Two characteristics (distance from sample point to the nearest perennial grass and the species) were combined to determine a rangeland condition index. At 22 of the 34 contrasts the condition index was significantly (P<0.05) higher on one side of the fence. There was no clear method to distinguish between the influences of different management inputs that may have caused the fenceline contrasts. Therefore, subjective judgment was relied upon to identify bush control as the most likely single causative factor at ten contrasts, stocking rate and period of rest at five contrasts each, and stocking density at two contrasts. Management contributed to both causes and consequences of fenceline contrasts. The negative correlation between stocking rate and rangeland condition index was weak (r = â0.2575, P = 0.04, n = 64), suggesting that there may have been more farms where a higher stocking rate was the cause of poorer rangeland than farms where the higher stocking rate was the consequence of better rangeland raising the carrying capacity. The stronger correlation between profit and income (r = 0.9288, P < 0.001, n = 25) than between profit and expenditure (r = 0.0267, P = 0.899, n = 25), suggests that farmers should focus on reducing non-essential expenditure to increase profitability. Game farming can earn high income, but continuous selective grazing by gregarious game animals may lead to poorer rangeland condition. Useful lessons were learnt from the case study of an innovative farmer who adapted his management based upon his keen observations of rangeland dynamics. Many of his interventions were strategically timed in relation to rainfall events. There is much that can be learnt by both scientists and other farmers from the management strategies applied by successful farmers who earn a good profit while sustaining the rangeland.

A trial was conducted to determine the total rumen degradable protein intake (RDPI) required to maximise the digestible organic matter intake (DOMI) of beef cows consuming low quality grass hay from the Northern variation of Cymbopogon-Themeda pasture type (pure grassveld). Thirty five pregnant Afrikaner x Simmentaler crossbred cows (±517.08kg, SD 53.06) were randomly allocated to 5 treatments. Treatments provided the following RDP levels/cow/day 0g, 180g, 360g, 540g and 720g. A RDP source, calcium caseinate (90% crude protein (CP) on dry matter basis and 100% rumen degradable) was used and mixed with molasses based concentrate. The cows had ad lib access to low quality grass hay (2.26% CP, 73.94% neutral detergent fibre). The trial period consisted of 14 days adaptation, 21 days intake study and 7 days digestibility study. No statistical significant (P > 0.05) influence of RDP level on the apparent digestibility of dry matter (DM), organic matter (OM) and neutral detergent fibre (NDF) was detected. The grass DM intake (DMI), DOMI and metabolisable energy intake (MEI) increased in a linear and quadratic manner (P < 0.05) with increasing levels of supplemental RDP. The single broken-line model predicted DOMI/kg BW0.75 with higher accuracy (R2 = 0.45) than the quadratic regression procedure (R2 = 0.07). According to this model 4.03g daily RDPI/kg BW0.75 or 8.07% RDP of DOM was required to maximise DOMI of pregnant beef cows consuming winter grassveld hay. In a second trial the potential to substitute true protein with urea was investigated. Urea replaced 0%, 25%, 50%, 75% and 100% of the natural supplemental RDP. The same procedure as described in the first trial was followed. The increasing proportion of urea did not significantly (P > 0.05) influence the apparent digestibility of DM, OM and NDF. There was a linear increase in grass DMI (P = 0.0355) at increasing levels of urea, with the highest intake observed when urea was used as a sole source of nitrogen (N). DOMI and MEI increased in both linear and a quadratic manner (P < 0.05) with increasing levels of urea. The molar proportions of acetic, propionic and butyric acid were not affected (P < 0.05) by the substitution of urea, while the molar percentages of iso-butyric and iso-valeric acid were significantly decreased (P < 0.0001) with increasing urea levels. Ammonia N increased linearly (P = 0.0426) while the ruminal pH was not affected (P > 0.05) by increasing the proportion of urea. It seems that urea can be the sole RDP source in supplements for pregnant beef cows consuming the low quality grass hay. In the third trial, the influence of replacing natural protein with urea on the performance of beef cows grazing natural winter grassveld was investigated. Pregnant Afrikaner x Simmentaler crossbred cows were randomly allocated to the two treatments. The number of cows per treatment varied between 18 and 28 each year. The trial was executed over four consecutive winter periods from 2003 to 2006. The treatment licks comprised of: 1) 100% supplemental RDP from urea and 2) 50% supplemental RDP from urea and 50% from cottonseed oilcake. Lick provision was controlled to ensure the total RDPI as recommended in the first trial. Increasing the proportion of supplemental RDP from urea did not have a significant (P = 0.9938) effect on the end live mass of the cows. The urea levels did not significantly influence (P > 0.05) weaning mass, corrected weaning mass and average daily gain of the calves. The lack of significant lick treatment effect on live mass, body condition score and performance of the calves suggests that urea can be used as a sole source of RDP.