No description available.

The expression of photorefractoriness, a feature of seasonal breeding in birds, is important in production species, where egg production and fertility are affected by the photoperiod. Years of selection in meat-type birds have reduced the potential reproductive function, and the environmental manipulation of such genotypes is essential to maximise productivity. While it is known that egg-type pullets no longer exhibit photorefractoriness, and that female broiler breeders do, there is not much information about the response of male broiler breeders to photoperiod. Such information is important when designing lighting programmes for breeding stock, and this study aimed to gain more insight into the male response to photoperiod. A series of experiments was designed in order to achieve this. In the first the response of male broiler breeders to rearing on constant photoperiods was measured, and in the second the effects of age at photostimulation on age at sexual maturity were assessed. The response to an increase in photoperiod during the production cycle was investigated in the third trial. Evidence of photorefractoriness in males was observed, but this was not the case in all birds, possibly due to high variation in some of the fertility traits measured. It seems possible that males do not respond to photoperiod to the same extent as females. Unexpected observations of a response in some birds to early photostimulation, and the high variation observed prompted another experiment in which the heritability of the response to early photostimulation was measured as a potentially revolutionary method of selection, whilst checking that this response is not negatively linked to broiler growth rates. Left and right testis weight data, collected in the above experiments, were analysed for asymmetry. There was no consistent response in testes asymmetry to photoperiod, or evidence that asymmetry in testis weights is as a result of the imposition of genetic or environmental stress. The strong correlation found between testes dimensions and weight suggests that predictions of testis weights could be made through ultrasonics or laparoscopy. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

No abstract available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

The effects of dietary fat on the reproductive performance of broiler breeder chickens have been studied. Individually caged broiler breeders were fed diets with or without added fat during 19-wk reproductive period. In Experiment 1, only the females were subjected to dietary treatments: control (no added fat), 3% animal-vegetable fat blend (A-V fat, 3% corn oil (CO)), while the males received a non-added fat diet. In Experiment 2, only the males were fed diets containing 0 or 3% of either A-V fat or CO while the females were provided a non-added-fat diet. / In Experiment 1, added dietary fat produced significantly higher fertility and early embryonic livability. In Experiment 2, inclusion of 3% CO in the males' diets significantly increased late embryo livability and total embryo survival resulting in a significantly higher hatchability. There were no differences in semen characteristics among dietary treatments. These data indicate that the contribution of the male is not restricted to the fertilization of eggs but is also related to embryonic livability. The addition of fat significantly affected the fatty acid composition of the phospholipid fraction of the spermatozoa cells.

No description available.

This study was conducted to examine the potential of plastic slats as flooring material for maintenance of broiler breeders. Although plastic slats are more expensive than wood slats, plastic slats are more durable and easier to clean. Wood and plastic slats were tested as full and partial flooring to determine the ideal proportion of slats for broiler breeder floors. Space allotment was 2040 cm²/bird on all floor treatments. . Arbor Acres broiler breeders, one of the more common strains in British Columbia, were raised to 58 weeks of age to monitor the influence of slat material and slat coverage on egg production and progeny growth over one production cycle. Since the pens were not set up to determine the number of eggs lost through slats, "egg production" values were actually egg recovery values. Over-all egg recovery was significantly higher on partial wood (PWS) and partial plastic slats (PPS) than on either of the full slat treatments. Breeders on full wood slats (FWS) had higher over-all egg production than those on full plastic slats (FPS). Differences were significant for three biweekly periods, but slats did not influence the over-all incidence of floor eggs and cracked floor eggs. The incidence of cracked nest eggs was significantly higher in FWS and FPS than in PWS and PPS pens during four lay periods and overall. The proportion of non-cracked nest eggs, which was taken as an approximation of the proportion of settable eggs, was higher for partial slat pens than full slat pens, and FWS pens had a higher proportion of non-cracked nest eggs than FPS pens. To monitor fertility and hatchability, eggs were incubated at 37, 42, 46, 50 and 56 weeks of breeder age. Fertility, hatchability of total eggs set and hatchability of fertile eggs was not affected by type of slats. Progeny from the hatch at 37, 46 and 56 week of breeder age were grown in Petersime battery cages to three weeks of age. The progeny of breeders on FPS had lower first week weight gain than the other progeny groups due to moisture loss when 7 FPS progeny were lost during the second growth trial. Weekly and over-all feed conversion of progeny was not affected by types of slats used by parents. The 56th week progeny were grown in Petersime battery cages to market age (six weeks). PWS and FPS progeny had higher third week weight gain than PPS progeny. During the sixth week, FWS and PWS progeny had higher weight gain than FPS and PPS progeny. The sixth week feed conversion of FPS progeny was higher than that of the other three progeny groups. No other differences were seen. As long as slats were used as partial flooring, there were no differences in egg production on wood or plastic slats. The proportion of "settable" eggs, fertility, and hatchability of eggs of plastic slat breeders were comparable with that of wood slat breeders regardless of slat coverage. There were significant differences in the 3-week growth of 37th, 46th and 56th week progeny and the 6-week growth of 56th week progeny on the different slat types, but the differences were not due to slat treatments. There was no interaction between breeder age and slat material, therefore the influence of slat material on egg production and progeny growth did not vary with breeder age. Although egg recovery and the number of settable eggs were lower for FPS breeders, breeders on plastic slats performed as well as those on wood slats in the present study. / Land and Food Systems, Faculty of / Graduate

There are negative influences of selection for broiler growth on the reproductive ability of broiler breeder parents. This is mostly due to problems related to excessive body weight, such as an inability to achieve successful cloacal contact during natural mating. There is also an age-related decline in fertility of broiler breeders. In attempts to prolong the fertile period of the breeders, various forms of management techniques have been employed. These include tools such as feed restriction, photoperiod management, spiking, and possibly even using artificial insemination. The first objective of this thesis was to investigate the possible benefits of feeding broiler breeder males diets containing lower crude protein levels, than given to the females, as a means of possibly tempering growth rate or improving semen quality and fertility. There was a definite improvement in the ability of the spermatozoa of the males on a lower crude protein diet to survive in the female reproductive tract. Males that received higher levels of crude protein were at a disadvantage in that fewer males yielded semen in response to abdominal massage. The second objective of this thesis was to assess the possible benefits in semen quality and fertility, when supplementing the male diets with additional vitamin E or Se in the form of Sel-Plex®. No significant effect of treatment was observed on egg fertility or semen quality. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

The aim of this study was to evaluate the effects of broiler maternal dietary lysine intake on progeny performance. Three experiments were conducted with chicks hatched from Cobb 500 breeders at 38, 48, and 60 weeks of age. Breeder hens received six dietary treatments (T1-T6) from 26 to 60 weeks of age, which allowed an intake of 800, 930, 1070, and 1200 mg lysine/bird/d (T1-T4) respectively. An intake of 800 mg/bird/d at 26 weeks was increased by 25 mg every two weeks to provide 1225 mg lysine/bird/d at 60 weeks (T5). An intake of 1200 mg/bird/d at 26 weeks was reduced by 25 mg every two weeks to supply 775 mg lysine/bird/d at 60 weeks (T6). A total of 320, 401, and 390 chicks were hatched from breeder hens at 38, 48, and 60 weeks of age respectively. Immediately after hatching, 270, 384, and 384 unsexed chicks from breeder hens at 38, 48 and 60 weeks of age respectively, were placed in an environmentally controlled room and randomly allocated (within a treatment) to single-tier cages (80 × 50 cm). Nine chicks from breeders at 38 weeks of age and 8 chicks from breeders at 48 and 60 weeks of age were placed in each pen, keeping chicks from the same treatment group together for 21 d. Chicks were fed ad libitum with a commercial broiler starter crumble for 21 d and water was provided ad libitum throughout the duration of each trial. Feed intakes (FI), body weight gain (BWG) and feed conversion ratio (FCR) were measured weekly. Data were subjected to analysis of variance using a generalized linear model of GenStat 12th edition. Simple linear regression model of GenStat 12th edition was used where appropriate. Significant improvements in offspring feed intake and body weight gain from 7-21 d were observed in chicks hatched from young breeder flocks (38 weeks) with low dietary lysine intakes (800, 930 and 950 mg/bird/d). The effect of maternal dietary lysine intake on offspring performance disappeared with the aging of the breeder flock (60 weeks). It was concluded that lower maternal dietary lysine intakes (800, 930 and 950 mg/bird/d) may improve feed intake and body weight gain from 7-21 d of broiler chicks hatched from younger breeder flocks (38 weeks). / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Fertility of Broiler Breeders (BBs) has been researched over many years with inconclusive findings. Genetic selection and improvements in growth traits have had negative effects on fertility of BB. One explanation is related to overweight birds, resulting in the inability of birds to copulate successfully, with no cloacal contact. The requirements of CP for egg production in BB females have been quantified, but there is less literature on how CP affects fertility in male BBs. The objective of this experiment was to investigate the effects of feeding BB males different dietary CP intakes (10.4, 12.4, 14.2, 17.8, 19.3 and 20.1 g CP/bird/day) on fertility in flocks with natural mating and in birds that were artificially inseminated (AI). Results showed that birds consuming 10.4 and 12.4 g CP/bird/day resulted in weight loss (between 24.9 and 23.6% and 26.5 and 22.4% below target BW) over the 29 weeks of the experimental period in both natural mating and individual pens respectively. Intakes of higher protein content (17.8- 20.1 g CP/bird/day) however resulted in BW gain over the experimental period. Hatch percentage across all CP intakes throughout the duration of the study was found to be high, ranging between 75- 100 and 80-95 % in AI and naturally mated birds respectively, and not affected by CP intakes. Similar results for predicted fertility using the methods published by Brillard & Antoine (1990) and Wishart (1997) were found; however Brillard & Antoine (1990) is more lenient requiring less outer perivitelline layer (OPVL) sperm/mm2 to pronounce an egg fertile. Improved fertility predictions could have been made by using examination of inner perivitelline layer (IVPL). There was a tendency for a superior response in predicted fertility from birds with a protein intake of 14.2 g CP/bird/day. This intake also least affected the BW of the male birds and thus 14.2 g CP/bird/day can be recommended for optimal BB male performance. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.