The objective of this study was to investigate fatty acid concentrations of homogenized and non-homogenized milk from Jersey and Holstein cows. Twenty-two, lactating Holstein (n=11) and Jersey (n=11) cows were fed the same ration with Calan® gates twice daily. Jerseys were fed 25kg DM and Holsteins were fed 30 kg DM. Feed offered was adjusted daily according to previous day orts amount. Body weight and measurements, blood, and ruminal samples were collected weekly as were feed and orts samples. Ruminal fluid was collected from six Holstein and six Jersey cows weekly (n=42). Milk weights were collected daily and samples were taken at 0300 and 1500 hours and pooled by week. There was no difference in fatty acid concentrations from milk of Holsteins compared to Jersey. There was a tendency (P < 0.08) for greater concentration of linolenate between breeds and of stearate between processes.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Monensin was approved in the 1970’s as a feed additive to ruminant diets. Since then, many studies on the effects of Monensin were done. Its mode of action includes the improvement of feed conversion by altering rumen fermentation. This alteration results in a change in the rumen microbial population. Some processes that benefit from the manipulation of rumen microbial population are volatile fatty acid production, peptide degradation and amino acid deamination. The use of ionophores as an antibacterial product in animal feeds were banned by the European union ( EU) in 2006 because of chemical residues found in the edible product making it potentially unhealthy for human consumption and it is also socially unacceptable. Thus, alternative sources need to be identified to help improve the rumen microbial population. Such an alternative could be plant based EO. Oregano (Origanum vulgare) is a natural anti-bacterial compound affecting a variety of gram positive and gram negative bacteria. It has been reported to improve the overall health and production of lactating dairy cows by enhancing rumen fermentation. The aim of this study was to determine the effect of an essential oil extracted from oregano on production and rumen fermentation of Jersey cows grazing ryegrass pasture during spring. Effects were determined on milk yield, milk composition, live weight body condition, rumen pH, Ammonia-nitrogen (NH3-N) and volatile fatty acid (VFA) composition, organic material (OM) and neutral detergent fibre (NDF) digestibility of pasture in the rumen. Fifty four early lactation Jersey cows were blocked, according to days in milk (DIM), 4% fat corrected milk (FCM) and lactation number. Cows within blocks were randomly allocated to one of the three treatments. The three treatments were as follows: Control (CON; maize based concentrate with no feed additives), an ionophore treatment, (MON; a maize based concentrate with monensin provided a daily dose at 300 mg per cow), and an essential oil treatment (EO; a maize based concentrate with oregano extract provided at a daily dose of 1.15 g per cow. Cows received 6 kg of concentrate in the milking parlour and were allocated 10 kg dry matter (DM) of ryegrass pasture, divided into two grazing periods after each milking. Before milking, cows were separated into their respective treatment groups for milking and the consumption of their specific concentrate treatments. Milk yield was recorded on a daily basis. Composite milk samples were collected per cow on a bi-weekly basis. Live weight and body condition score (BCS) were determined before and after the study. Six rumen cannulated cows were used in the rumen study. Two cows were randomly allocated to each of the three treatments in a 3 x 3 Latin square design (three treatments and three periods) thus all the cows were subjected to all three treatments over the experimental period. Ruminal pH, volatile fatty acids (VFA) concentration, ruminal ammonia-nitrogen (NH3-N), and in sacco degradability were determined. The daily average milk yield and milk fat content did not differ among treatments (P > 0.05) and were 20.5, 20.3 and 20.4 kg per cow and 4.5, 4.5 and 4.6 % for cows receiving the CON, MON and EO concentrates respectively. Milk protein and milk lactose content increased (P < 0.05) for the two additive treatments in comparison to control and were 3.39b, 3.55a and 3.60a % for milk protein and 4.50b, 4.80a and 4.80a % for milk lactose where cows received the CON, MON and EO treatments, respectively. Ruminal pH values did not differ among treatments, however, the average overall pH over the 24 hour profile was higher for the two additive treatments. There were no differences in total volatile fatty acid concentrations among the three treatments. With regards to individual VFA, propionate was decreased in the MON treatment when compared to the CON treatment. The ruminal ammonia nitrogen concentration did not differ among treatments. There were no differences in DM and NDF degradability (DMd and NDFd) on the 6 h incubation period but monensin increased the DMd at 30 h incubation and both monensin and oregano increased NDFd after 30 h incubation. To conclude the use of monensin and oregano oil extract have shown to be beneficial with regards to increasing the milk protein and milk lactose content as well as the NDFd. The average overall pH from the pH profile resulted in the two additive treatments being higher when compared to the control treatment. This could be beneficial to rumen fermentation and have a positive effect on the microbial population. As monensin and oregano oil extract showed similar results, oregano oil extract can be considered as an alternative natural feed additive to monensin. / AFRIKAANSE OPSOMMING: Monensin is in die 1970's goedgekeur as 'n voerbymiddel in herkouerdiëte. Sedertdien het navorsing met betrekking tot die invloed van monensin vinnig toegeneem. Die werking van monensin sluit die verbetering van voeromsetting in deur die verbetering van rumenfermentasie. Die verandering in rumenfermentasie het ‘n invloed op die rumenmikrobiese bevolking. Sommige prosesse wat voordeel trek uit die manipulasie van die rumenmikrobiese bevolking is onder andere vlugtige vetsuurproduksie, peptiedafbraak en aminosuurdeaminering. Die gebruik van ionofore as 'n antibakteriese produk in veevoere is gedurende 2006 deur die Europese Unie verbied as gevolg van chemiese residue wat in die eetbare produk gevind is. Die residue maak dit moontlik ongesond vir menslike verbruik en dit is ook nie sosiaal aanvaarbaar nie. Alternatiewe produkte wat help om die rumenmikrobiese bevolking te verbeter en manipuleer moet geïdentifiseer word. Een alternatiewe produk is plantgebasseerde essensiële olies. Origanum (Origanum vulgare) is 'n natuurlike anti-bakteriële produk wat 'n verskeidenheid van gram-positiewe en gram-negatiewe bakterieë in die rumen beïnvloed. Daar is gevind dat die algemene gesondheid en produksie van 'n lakterende melkkoeie verbeter deur die verbetering van rumen fermentasie. Die doel van hierdie studie was om die invloed van 'n essensiele olie-ekstrak uit oreganum op die produksie en rumenfermentasie van Jerseykoeie wat raaigras gedurende die lente bewei, te bepaal. Effekte is ondersoek op melkproduksie, melksamestelling, lewende massa, liggaamskondisie, rumen pH, ammoniak stikstof konsentrasie (NH3-N) en vlugtige vetsuursamestelling (VFA) asook ruminale droeë materiaal (DMd)- en vesel-verteerbaarheid (NDFd) van die weiding. Vier en vyftig Jersey koeie in vroeë laktasie is geblok volgens dae in melk (DIM), 4% vet gekorigeerde melk (VGM) en laktasie nommer. Koeie binne blokke is ewekansig aan een van die drie behandelings toegeken. Die drie behandelings was as volg: Kontrole (CON, mielie-gebaseerde konsentraat met geen voer-bymiddel nie), ‘n ionofoor-behandeling (MON; mielie-gebaseerde konsentraat met monensin teen 300 mg / koei per dag), essensiële olie-behandeling (EO; mielie-gebaseerde konsentraat met oreganum ekstrak teen 1.15 g / koei per dag). Koeie het 3 kg konsentraat in die melkstal ontvang met elke melking en 10 kg droeë material (DM) raaigras-weiding is per koei toegeken. Weidingsessies is verdeel in twee periodes, naamlik na elke melking. Voor melking is die koeie geskei om te verseker dat hulle die regte behandeling in die melkstal ontvang. Melkproduksie is daagliks aangeteken. Saamgestelde melk monsters is tweeweekliks per koei versamel. Lewende massa (LW) en liggaamskondisie (BCS) is aan die begin en teen die einde van die studie bepaal. Ses rumen-gekannuleerde koeie is in die rumen studie gebruik. Twee koeie is toegeken aan elk van die drie behandelings in 'n 3 x 3 Latynse vierkant ontwerp (drie behandelings en drie periodes) en al die koeie het gevolglik al drie behandelings gedurende die eksperimentele periode ontvang. Ruminale pH, VFA konsentrasie, ruminale NH3-N, en in sacco degradeerbaarhede; DMd en NDFd is bepaal. Die daaglikse gemiddelde melkproduksie en melkvetinhoud het nie beduidend tussen behandelings verskil nie (P > 0.05) en was 20.5, 20.3 en 20.4 kg/koei per dag en 4.5, 4.5 en 4.6% vir koeie op die drie behandelings (CON, MON, EO), onderskeidelik. Melk proteïen en melk laktose het aansienlik toegeneem (P < 0.05) vir die twee behandelings met die supplemente in vergelyking met die CON behandeling met waardes van 3.4, 3.6 en 3.6% vir melk proteïen en 4.5, 4.8 en 4.8% vir koeie op die CON, MON en EO behandelings, onderskeidelik. Die rumen pH oor 24 uur het nie verkil tussen die drie behandelings nie en die totale VFA konsentrasie het ook nie verskil nie. Die propionaatkonsentrasie het wel afgeneem op die MON behandeling in vergelyking met die CON. Die rumen NH3-N het nie tussen die drie behandelings verskil nie. Die DMd en NDFd verteerbaarhede van die raaigras in die rumen het nie verskil na ‘n 6 h inkubasieperiode nie. Na 30 h inkubasie het monensin ‘n hoër DM verteerbaarheid getoon en in beide die MON en EO-behandelings het die NDF-verteerbaarheid verhoog wanneer dit vergelyk word met die CON. Om saam te vat; die gebruik van monensin en oregano olie ekstrak het getoon dat dit voordelig kan wees met betrekking tot die verhoging van die melk proteïen en melk laktose inhoud, sowel as die NDFd. Die gemiddelde pH van die pH profiel het gelei tot hoër gemiddeldes vir die twee voerbyvoegsel behandelings in vergelyking met die kontrole behandeling. Dit kan voordelig wees om rumen fermentasie te verbeter en dus ‘n positiewe uitwerking te hê op die mikrobiese bevolking. Monensin en oregano olie ekstrak het soortgelyke resultate getoon en daarom kan oregano olie ekstrak beskou word as 'n alternatiewe natuurlike voerbyvoegsel.

During spring kikuyu-ryegrass pasture has a low dry matter (DM) content (10-12%), is highly digestible and has high levels of soluble carbohydrates. Low rumen pH values have been recorded for cows grazing these pastures even when supplemented with low levels of concentrate. The rumen environment and extent of rumination may therefore be sub-optimal. Supplementation of the pasture with dry roughage may improve rumination, the rumen environment and therefore also milk production performance. The aim of the study was to determine if strategic supplementation of lucerne hay will improve milk production, milk composition and the rumen environment of cows grazing high quality kikuyu/ryegrass during spring and receiving low levels of concentrate. Forty eight high producing Jersey cows were blocked and randomly allocated to one of the following treatments: control (no supplemental roughage), supplementation of 1.0 kg lucerne hay and supplementation of 2.0 kg lucerne hay after morning milking. Cows received 5 kg of dairy concentrate per day during milking. Cows grazed as one group and pasture was allocated to ensure a post grazing height of 10-12 on the rising plate meter (5-6 cm). The average post grazing pasture height for the experimental period was 10.83±1.68 (n=73) on the RPM (5.42 cm). There were no differences (P >0.10) between the treatments for 4% fat corrected milk production, which were 22.2 kg/d for the control, and 22.5 kg/d and 22.9 kg/d for the 1 kg and 2 kg lucerne treatments respectively. Milk fat and protein percentage was not affected (P >0.10) by supplementation of lucerne hay. The milk lactose content of cows receiving the control and 1 kg lucerne hay treatments were higher (P <0.05) than those of cows receiving the 2 kg lucerne hay treatment. Eight rumen cannulated Jersey cows were randomly allocated to either the control or the 2 kg lucerne hay treatment in a cross-over design. These cows grazed together with the cows of the production study and received the same dairy concentrate. Rumen pH was measured for 48 hours with 10 minute intervals using an automated pH logging system. Rumen samples were taken at 08:00, 14:00, 20:00 and 02:00 and were analysed for ammonia-nitrogen (NH3-N), volatile fatty acids (VFA) and pH. An in sacco study was conducted to determine DM and neutral detergent fibre (NDF) disappearance of ryegrass. There were no differences (P >0.10) between treatments in overall mean pH, measured with either the logging systems or with the portable pH meters averaging 6.18 and 6.11 for cows receiving the control and the 2 kg lucerne treatment respectively. The mean rumen NH3-N did not differ (P >0.10) between treatments. The mean concentration of acetic acid and the total VFA concentration was higher (P <0.05) for cows receiving the 2 kg lucerne treatment compared to the control. There were no differences (P >0.10) between treatments in the DM or NDF disappearance of ryegrass after 24 hours. Supplementation of lucerne hay to cows grazing well managed kikuyu-ryegrass pasture during spring did not improve milk production, milk composition, rumen pH or in situ NDF disappearance of ryegrass Results suggest that cows grazing kikuyu/ryegrass pastures supplemented with low levels of concentrate consume sufficient eNDF to maintain a favourable rumen environment and normal milk composition. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

Energy is the first-limiting nutrient for cows grazing pasture therefore, energy supplementation is necessary for high producing animals. In pasture-based systems, the concentrate is fed twice a day in the dairy parlour during the milking procedure. Consumption of large amounts of fermentable carbohydrates results in a drop in rumen pH and this may induce rumen acidosis. This may lead to reduced intake, lower fibre digestion and depressed milk yield. Supplemental yeast offer great possibilities in stabilising the rumen fermentation patterns and, therefore, improving dry matter intakes (DMI). This may increase milk production, milk composition parameters, rumen volatile fatty acid concentrations (VFA) which leads to higher profits. Investigating these responses, a trial was conducted, where live yeast (Levucell SC 10 ME-Titan) was supplemented to Jersey cows grazing ryegrass/kikuyu pastures, supplemented with 6 kg (as is) dairy concentrate per day split over two milking periods. Thirty multiparous high-producing Jersey cows between 30 and 120 days in milk (DIM) were selected, blocked and randomly allocated to control (no yeast) or live yeast treatment groups. Ten fistulated lactating cows were added in a cross-over design (two periods and two treatments) and all 40 cows strip grazed Italian ryegrass (Lollium multiflorum) and kikuyu pastures as one group. A new pasture strip was allocated after each milking and pasture was measured using a rising plate meter (RPM). The yeast product Levucell SC 10 ME – Titan containing Saccharomyces cerevisiae CNCM I-1077 was supplied by Lallemand S.A.S (19 rue des Briquetiers, 31702 Blagnac cedex, France). The Levucell SC 10 ME – Titan is a micro-encapsulated formulation for premix and pelleted feeds. The yeast treatment group had the yeast pelleted in with the dairy concentrate at a concentration of 167 g of yeast per ton of concentrate, to obtain the required intake of 1 g yeast per cow per day as specified by Lallemand. Milk yields were recorded daily and composite milk samples were taken every two weeks to determine, milk fat, protein, lactose, milk urea nitrogen (MUN) and somatic cell count (SCC) contents. The fistulated cows were adapted to their respective diets and treatments for 21 days after which the pH measurment, rumen fluid sampling, and In sacco study were conducted. Milk yield, 4% fat corrected milk (FCM) yield, milk protein and lactose percentages, SCC, body condition score (BCS), and live weight did not differ (P > 0.05) between treatments. The milk fat% however, was higher for the yeast supplemented cows at 4.24% compared to the control group of cows of 3.99% (P < 0.05). The mean acetic and total VFA concentration (mmol/L) for the control treatment was higher compared to the yeast treatment (P < 0.05). There was no difference in the fermentation patterns of VFA, the pH and NH3-N values measured between treatments (P > 0.05). The mean In sacco neutral detergent fibre (NDF), organic matter (OM) and DM disappearance was higher for the yeast treatment group of cows after a 12 and 24 hour incubation compared to the control group (P < 0.05). The mean ruminal NDF disappearance of ryegrass in cows supplemented with yeast increased by 11.9% and 6.3% compared to the control at the 12 and 24 hour incubation periods, respectively. With higher fibre digestibilities in the rumen and more acetate available at the mammary gland and subsequently higher milk fat percentages, the yeast effects on stimulating the cellulolytic bacteria in the rumen, may be a possible explanation for the results in the current study and it is well documented in previous studies. Live yeast supplementation resulted in higher milk fat percentages which improved milk price. / Dissertation (MSc(Agric))--University of Pretoria, 2011. / Animal and Wildlife Sciences / unrestricted

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Genetic selection for high milk production, type and appearance for the last 50 years has suppressed secondary traits such as reproductive performance, productive life, health and survivability in the pure milk breeds. The economic importance of these secondary traits in dairy production systems is the basis for the interest seen in crossbreeding. The problem of growth rate of heifers, cow fertility, reduced disease resistance and small body frame for beef production in Jerseys can be improved by crossing Jerseys with dual purpose breeds, such as Fleckviehs which possess a more beef potential. Against this background, this study aimed at comparing the production and reproduction of Jersey and Fleckvieh × Jersey cows in a pasture-based system. Milk recording was done according to standard milk recording procedures. Milk production (milk, fat, and protein yield) was adjusted to 305 days of lactation and corrected for age at calving. Effects of breed, parity, month and year were estimated for milk, fat and protein yield as well as fat and protein percentage using general linear models procedure. The fixed effects identified as having significant effects on milk, fat and protein yield were breed, parity and year. F×J cows produced significantly more milk than J cows (6141 ± 102 vs. 5398 ± 95 kg milk). Protein and fat yield were significantly higher in F×J (201 ± 3 and 272 ± 4 kg, respectively) than in J cows (194 ± 2 and 246 ± 3 kg, respectively). There percentages of fat and protein differed slightly between the two breeds with the Jersey recording slightly higher percentages (4.61 ± 0.04 and 3.62 ± 0.03 %, respectively) compared to the F×J cows’ percentages, which were, respectively, 4.47 ± 0.04 and 3.51 ± 0.03 %. It was concluded that F×J crossbred cows were more productive than purebred J cows probably owing to heterotic effects. Heifers were inseminated at 13 months of age and cows 40 days post-calving. Using insemination records and pregnancy check results, fertility traits were analyzed and compared between the two breeds, using analysis of variance for continuous records. Conception age was the same for both breeds resulting in a similar age at first calving. For cows, the interval from calving to first insemination was significantly shorter (P <0.001) in crossbred cows being 76.7 ± 2.2 days compared to 82.4 ± 2.5 days for purebreds. A larger proportion (P < 0.001) of 0.70 for crossbred cows was inseminated within 80 days after calving compared to 0.54 for J cows. Although the absolute number of days between calving and conception (DO) was lower for F×J cows in comparison to J cows (104.8 ± 6.8 vs. 114.8 ± 8.1days, respectively), the difference was not significant. However, the proportion of F×J cows confirmed pregnant by 100 days in milk was 0.79, which was higher (P < 0.001) than the 0.66 for J cows. Results indicate the potential of improving reproductive performance of J cows through crossing with dual-purpose breeds. The beef production of purebred J and Fleckvieh x Jersey (F×J) bull calves was compared, where bull calves were reared similarly for veal, i.e. carcass weight not exceeding 100 kg, or as steers for beef to 21 months of age. In both the veal and steer production systems, the mean birth weight were higher (P < 0.001) for crossbred in comparison to J calves and steers (33.5 ± 1.2 kg vs. 27.9 ± 1.2 kg for veal) and (33.4 ± 0.9 kg vs. 26.9 ± 0.9 kg for steers) respectively. The live weight at 6 months of age was 163.5 ± 3.9 kg for J bull calves, which was lower (P < 0.001) than that for F×J bull calves (180.6 ± 4.0 kg). The F×J bull calves had a significantly higher average daily gain (ADG) of 0.82 ± 0.02 kg/day compared to 0.73 ± 0.02 kg/day for J bulls. Marketing age differed (P < 0.001) in the veal production system with F×J and J bull calves marketed at 7.1 ± 0.1 and 6.3 ± 0.1 months, respectively. End live weight at 21 months of age was significantly higher (P < 0.001) in F×J bulls (441.4 ± 14.9 kg) than the 322.6 ± 13.4 kg in J bulls; while ADG differed (P < 0.001) between the two breeds being 0.64 ± 0.02 and 0.46 ± 0.0 kg/day in F×J and J bull calves, respectively. Crossbred steers had a significantly higher carcass of 206.5 ± 8.9 kg compared to 157.9 ± 8.6 kg for J steers. Results indicate the potential of improving beef production characteristics of the J cattle through crossbreeding. / AFRIKAANSE OPSOMMING: Genetiese seleksie vir hoë melkproduksie, tipe en voorkoms die afgelope 50 jaar het sekondêre eienskappe soos reproduksie, produktiewe lewe, gesondheid en oorlewing onderdruk in die suiwer melk rasse. Die ekonomiese belangrikheid van hierdie sekondêre eienskappe in melkproduksie stelsels is die basis vir kruisteling. Probleme soos groei tempo van verse, koei vrugbaarheid, verlaagde weerstandbiedenheid teen siektes en klein liggaam raam vir vleisproduksie in Jerseys kan verbeter word deur die kruising van Jerseys met ' n dubbele doel rasse, soos Fleckviehs wat beskik oor beter vleis potensiaal. Teen hierdie agtergrond, is hierdie studie daarop gemik om produksie en reproduksie van Jersey en Fleckvieh x Jersey koeie in 'n weiveld - gebaseerde stelsel te vergelyk. Melk opname is gedoen volgens standaard melkaantekening prosedures. Melkproduksie (melk-, veten proteïen opbrengs) was aangepas vir 305 dae van laktasie en gekorrigeer vir kalf ouderdom. ‘n Algemene lineêre model was gebruik om die effekte van ras, pariteit , maand en jaar op melk-, vet- en proteïen opbrengs sowel as vet- en proteïen persentasie te bepaal. Die vaste effekte geïdentifiseer met 'n beduidende effek op melk-, vet- en proteïen opbrengs was ras, pariteit en jaar. F × J koeie het aansienlik meer melk as J koeie (6141 ± 102 teen 5398 ± 95 kg melk) produseer . Vet opbrengs was aansienlik hoër in F × J koeie as in J koeie (272 ± 4 246 teen ± 3 kg vet). Proteïen opbrengs was ook aansienlik hoër in F × J koeie as J koeie (201 ± 3 vs 194 ± 2 kg proteïen). Vet en proteïen persentasies het geneig om effens te verskil met 'n klein effek (4.61 ± 0.04 % vet en 3.62 ± 0.03 % proteïen) vir J koeie en (4.47 ± 0.04 % vet en 3.51 ± 0.03 % proteïen) vir F × J koeie. Daar is tot die gevolgtrekking gekom dat F × J gekruisde koeie kan meer produktief wees as suiwer J koeie weens heterotiese effekte. Verse kunsmatig geïnsemineer was op 13 maande ouderdom en koeie 40 dae na- kalwing aangehou was. Met behulp van bevrugting en swangerskap rekords, is vrugbaarheid eienskappe ontleed en vergelyk tussen die twee rasse, met behulp van ontleding van variansie vir deurlopende rekords. Ouderdom van bevrugting was dieselfde vir beide rasse wat in 'n soortgelyke ouderdomsgroep was by eerste kalwing. Vir koeie was die interval van kalf tot eerste inseminasie aansienlik korter (P < 0.001) vir kruisgeteelde koeie wat 76.7 ± 2.2 dae in vergelyking met 82.4 ± 2.5 dae suiwerrasse is. ‘n Groter proporsie ( P < 0.001) van 0.70 vir gekruisteelde koeie is binne 80 dae na kalwing geïnsemineer in vergelyking met 0.54 vir J koeie. Alhoewel die absolute aantal dae tussen kalwing en opvatting (DO) laer was vir F × J koeie in vergelyking met J koeie (104.8 ± 6.8 teen 114.8 ± 8.1dae, onderskeidelik), is die verskil nie betekenisvol nie. Maar die verhouding van F × J koeie wat swanger bevestig is met 100 dae in melk was 0.79, wat hoër was (P < 0.001) is as die 0.66 vir J koeie. Resultate dui daarop dat daar potensiaal is reproduktiewe prestasie te verbeter van J koeie deur kruisteling met 'n dubbel- doel rasse. Die vleisproduksie van suiwer J en Fleckvieh x Jersey (F × J) bulkalwers vergelyk. Die bul kalwers is soortgelyk grootgemaak vir kalfsvleis, d.w.s karkas gewig mag nie 100 kg oorskry as bulkalwers nie, en as osse vir vleis tot 21 maande oud. In die kalwers- en os produksie stelsels, was die gemiddelde geboorte gewig hoër (P < 0.001) vir die kruise in vergelyking met J kalwers en osse (33.5 ± 1.2 kg teen 27.9 ± 1.2 kg vir kalwers) en (33.4 ± 0.9 kg vs . 26.9 ± 0.9 kg vir osse) onderskeidelik . Die lewendige gewig op 6 maande ouderdom was 163.5 ± 3.9 kg vir J bulkalwers en was hoër (P < 0.001) vir F × J bulkalwers 180.6 ± 4.0 kg. Die F × J bul kalwers het 'n aansienlik ‘n hoër gemiddelde daaglikse toename (GDT) van 0.82 ± 0.02 kg/dag in vergelyking met 0.73 ± 0.02 kg/dag vir J bulle. Bemarkingsouderdom verskil (P < 0.001) in die kalf produksie stelsel met F × J en J bulkalwers bemark op 7.1 ± 0.1 en 6.3 ± 0.1 maande , onderskeidelik. Finale lewendige gewig van 21 maande oud was aansienlik hoër 441.4 ± 14.9 kg in F × J bulle as 322.6 ± 13.4 kg in J bulle , terwyl GDT hoër was (P < 0.001), met 0.64 ± 0.02 kg/dag en 0.46 ± 0.0 kg/dag in F × J en J bulkalwers, onderskeidelik. Gekruisde osse het 'n aansienlik hoër karkasgewig 206.5 ± 8.9 kg in vergelyking met 157.9 ± 8.6 kg van J osse. Resultate dui daarop dat daar potensiaal is om die beesvleis produksie-eienskappe van die J beeste te verbeter d.m.v. kruisteling.

Ruminant feed supplements are price sensitive and are effected by the continuous fluctuation of other raw material feed prices. Therefore, improving the efficiency of production and reducing cost of supplement concentrates for dairy cows are becoming increasingly important both for the smallholder and commercial dairy farmer. This can be overcome by replacing expensive energy and protein feeds with cheaper by-products. During periods of high maize prices, replacing maize with lower cost high fibre by-products becomes an economically viable option. Palm kernel expeller (PKE) fits the profile of a low cost, high fibre by-product. The aim of this study was to determine the effect of different inclusion levels of PKE in dairy concentrates for Jersey cows on milk production, milk composition, body weight (BW) and body condition score (BCS) change, rumen parameters and in situ ruminal kikuyu/ryegrass pasture degradability of dry matter (DMd) and neutral detergent fibre (NDFd) as well as NDFd rate (NDF kd). The study was conducted at the Outeniqua Research Farm situated near George in the Western Cape and cows grazed high quality kikuyu/ryegrass pasture during spring. Forty eight multiparous high producing Jersey cows were blocked according to 4% fat corrected milk (FCM), days in milk (DIM) and lactation number and randomly allocated to three treatments (control, low PKE, and high PKE). The PKE inclusion level in the control, low PKE, and high PKE treatment concentrates was 0, 20, and 40%, respectively. The PKE replaced part of the maize and protein sources in the concentrate. Milk yield was recorded daily and milk composition was determined in two week intervals over a 60 d period, after a 21 d adaptation period. Additionally, eight lactating rumen-fistulated cows were randomly allocated to the control and high PKE treatment in a two period crossover design. Ruminal pH, volatile fatty acids (VFA’s), ruminal ammonia-nitrogen (NH3-N), and in situ ruminal kikuyu/ryegrass pasture DMd, NDFd and NDF kd were measured. Cows received 6 kg (as is) concentrate per day divided over two milking periods and strip grazed kikuyu/ryegrass pasture as one group. Milk yield and milk fat content did not differ (P > 0.05) between treatments and were 21.3, 21.3 and 20.7 kg/cow/d and 4.63, 4.65, and 4.66% for cows receiving the control, low PKE and high PKE treatments, respectively. Milk protein, milk urea nitrogen (MUN), BW and BCS did not differ (P > 0.05) between treatments. Total VFA’s, average ruminal pH, ruminal NH3-N, and in situ ruminal kikuyu/ryegrass pasture DMd and NDFd as well as NDF kd did not differ (P > 0.05) between treatments. The acetic to propionic acid ratio was, however, higher (P < 0.05) for cows supplemented with the high PKE treatment. It can be concluded that partial replacement of maize with 20 or 40% PKE in a lactating dairy cow concentrate did not affect milk yield, milk fat content, milk protein content, somatic cell count (SCC), BW, or BCS. Rumen fermentation was unaffected and a healthy rumen environment was sustained. The replacement of higher cost maize and soybean oilcake by a lower cost PKE decreased feed cost. It is however not recommended to include PKE at 40% in the concentrate due to the increased time spent by cows in the milking parlour and the low palatability of PKE, which could lead to the tendency of increased concentrate refusals. It can be extrapolated from the data obtained from this study that milk production will be sustained when PKE is fed to cows on pasture at 2.4 kg/cow/day. / Dissertation (MSc Agric)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted

Thesis (MScAgric)--Stellenbosch University, 2012 / ENGLISH ABSTRACT: Ruminal pH is the rumen condition that varies most. Studying the cause and effect of diurnal variation offers a means of improving ruminal conditions for rumen micro-organisms with subsequent improvements in fibre degradation, milk yields and milk composition. A research project was conducted to test the following hypothesis: feeding 6 kg (as is) concentrate per cow/day in different weight ratios, divided in a morning and an afternoon allocation, will result in an improved ruminal pH profile and a concurrent increase in fibre fermentation, milk yield and improved milk composition. The project was conducted at the Outeniqua Research Farm in the Southern Cape of South Africa. A randomized block design was used and two phases, viz. ryegrass phase and a kikuyu phase, were applied. Each phase was conducted during the growing season of the grass specie used as pasture. A rumen study and a production study were done in each phase. The rumen study used six cannulated multiparous cows per treatment, testing rumen pH, volatile fatty acid (VFA) concentration, in sacco degradation of neutral detergent fibre (NDF) and dry matter (DM). The production study used 42 multiparous cows, blocked according to days in milk (DIM), parity and milk yield, and cows were randomly divided into three treatment groups. The study tested milk yield, milk composition and changes in body weight (BW) and body condition score (BCS). Treatments consisted of a maize based concentrate supplement (6 kg per cow/day, as is) being fed to cows on pasture in different weight ratios between morning and afternoon allocation. Treatments used in the production study were: Concentrate fed: 5 kg during morning; 1 kg during afternoon • Concentrate fed: 4 kg during morning; 2 kg during afternoon • Concentrate fed: 3 kg during morning; 3 kg during afternoon The first and the last treatments mentioned above were used in the rumen studies. Results of the rumen study of the ryegrass phase showed no differences in ruminal pH between treatment means. The time (h) spent below the critical ruminal pH, i.e. 5.8, was of short duration (2.92 to 3.42 hours). The concentration of certain VFA’s differed at times, but the differences were not reflected in graphs and data of the ruminal pH. No differences were observed in in sacco NDF and DM degradation between treatment means. Similar results were mostly obtained in the kikuyu phase. No differences were found in either daily maximum, minimum or mean ruminal pH between treatment means. Though time (h) spent below the critical ruminal pH was of a long duration (7.1 hours) it did not differ between treatments. No differences were observed between treatment means for in sacco NDF and DM degradation. Results of the production study of the ryegrass phase showed no differences in milk yield or milk composition between treatment means. The same was observed in the kikuyu phase except that milk fat was higher in the treatment group that received the 3:3 kg ratio treatment. The fact that treatments did not differ in terms of milk yield and milk composition in the production studies can be attributed to no differences between treatments in terms of rumen parameters observed in the rumen studies. Thus, feeding a higher proportion of concentrate in the morning relative to the afternoon for a total of 6 kg per cow/day does not affect ruminal pH, fibre digestion or milk production. Based on the results of both phases it can be concluded that the null hypothesis should be rejected. / AFRIKAANSE OPSOMMING: Die invloed van kragvoer voedingsstrategieë op rumen parameters, melkproduksie en melksamestelling van Jerseykoeie op raaigras- (Lolium multiflorum) of kikoejoe- (Pennisetum clandestinum) weidings. Die invloed van kragvoer voedingsstrategieë op rumen parameters, melkproduksie en melksamestelling van Jerseykoeie op raaigras- (Lolium multiflorum) of kikoejoe- (Pennisetum clandestinum) weidings. Behandelings toegepas in die produksiestudie het bestaan uit ‘n kragvoeraanvulling met ‘n mieliebasis wat aan koeie op weidings gevoer is in verskillende gewigsverhoudings tussen oggend- en middagvoeding, as volg: Behandelings toegepas in die produksiestudie het bestaan uit ‘n kragvoeraanvulling met ‘n mieliebasis wat aan koeie op weidings gevoer is in verskillende gewigsverhoudings tussen oggend- en middagvoeding, as volg: