Zugl.: Kiel, Universiẗat, Diss., 1987.

This trial was conducted in two phases during the period of February 2002 – June 2003. In phase 1 of the study the growth potential of calves fed either commercial Surromel Calf® (CSM) or experimental Surromel Calf (ESM) without calf starter was evaluated. In phase 2 of the study calves were fed either experimental Surromel Calf (ESM) or full milk with starter. High production cost and the availability of new technology prompted Clover SA to investigate other processes of manufacturing Surromel Calf®. The implementation of a new manufacturing process however, also necessitates evaluation of the end product. Twenty four Holstein heifer calves were used in a completely randomized block design. Calves were liquid fed only. For the first two weeks the milk replacer was allocated at 10% of body weight (2l fed twice daily), from week 3 to week 6 at 12.5% of body weight (2.5l fed twice daily) and during week 7 and week 8 calves received the milk replacer at 15% of body weight (3l milk fed twice daily). Water was available ad lib except for 30 minutes before and after milk replacer feedings. Body weight and skeletal development (body length, shoulder height, shoulder width and chest diameter) were measured weekly. The fecal consistency was subjectively scored daily. Mean average daily gains were 170g/day and 176g/day for calves receiving either ESM or CSM respectively. No differences were observed between treatments (P>0.05) for any change in body stature measurements over the 56 day trial period. If a price-competitive milk replacer could guarantee similar growth results as full milk, then milk producers would have confidence in using these replacers instead of full milk. In phase 2 of the trial calves were fed either 2l of full milk (FMS) or experimental Surromel Calf (EMSS) twice daily from birth up to 56 days. Calves had ad lib access to a commercial calf starter. Starter consumption was negligible for the first three weeks. Starter intake was 0.30kg/d and 0.34kg/d respectively at 35 days of age and 1.11kg/d and 1.10kg/d for FMS and EMSS calves respectively at 56 days (P>0.05). The average daily gain (ADG) were 370g/day and was unaffected by treatment (P>0.05). No differences were observed between treatments (P>0.05) for any change in body stature measurements. Growth standards for dairy calves with body weight less than 100kg have been included for the first time in the NRC Dairy 2001. Many producers are reluctant to use these recommendations since these have not been validated under South African conditions. The growth prediction was only compared with the growth of calves in Phase 2. The results showed that the NRC growth predictions are in agreement from week 3 onwards with the current study‘s growth results. / Dissertation (MSc (Agric) : Animal Nutrition)--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted

Thirty high-producing multiparous Holstein cows were used in a completely randomized block design to compare a lysine deficient total mixed ration, which was sufficient in methionine, to the same diet supplemented with a rumen protected lysine product. The CPM-Dairy prediction model was used to estimate the nutrient requirements and adequacy or deficiency of amino acids. During the 21-day prepartum transition period, cows were fed 4 kg (dry basis) of the lysine deficient diet plus Eragrostis curvula hay ad lib. After calving, cows were fed the lysine deficient diet for the first three weeks and were then blocked according to the average production from day 19-21. Fifteen cows were allocated to each treatment and blocked into 15 groups of two each. Data on production parameters were analyzed for all cows and also separately for cows in the 10 highest production blocks. The experimental period was from day 22 to 120 postpartum. Lysine supplementation resulted in an optimal dietary lysine : methionine ratio in metabolisable protein of 7.2 : 2.4. Lysine supplementation did not affect dry matter intake, milk production, milk fat percentage, milk protein percentage, milk urea nitrogen, body weight or body condition score; but decreased the non-casein nitrogen and whey content of milk. Furthermore, milk casein, which is the milk nitrogen fraction most sensitive towards increased duodenal supply of lysine and methionine, was not affected. The rumen protected lysine product evaluated did not improve cow productivity, probably because the product was either unprotected from rumen degradation, or overprotected to the extent that the lysine was not available for absorption in the small intestine; or absorbed but could not be metabolised. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

Virginiamycin (V) and Ionophores, such as Poulcox (active ingredient monensin sodium), are antimicrobial feed additives approved for use in cattle to improve performance. The effect of virginiamycin on Gram positive bacteria is similar to that of monensin (M) although the modes of actions differ. Very little information is available on the potential synergistic effects of V and M, especially in dairy cattle diets. The objectives of this study were to investigate the effect of combinations of V and M on the performance of dairy cows. Forty high producing Holstein cows were blocked according to previous milk production and randomly allocated to one of the following lucerne based total mixed diets: 1) Control, no medication (C); 2) Control plus 20 ppm virginiamycin (V); 3) Control plus 15 ppm monensin (M); 4) Control plus 20 ppm virginiamycin and 15 ppm monensin (V+M). The experimental period was from 21 days prepartum until 60 days postpartum. Data were analysed according to a randomized block design, using the model GLM procedure (SAS, 2001). Dry matter intake varied from 23.6 kg/d to 25.4 kg/d and did not differ between treatments (P>0.10). Milk production was higher (P<0.10) for cows receiving V+M (41.2 kg/d) when compared to cows receiving only V (36.6 kg/d), but did not differ from other treatments (P>0.10). Milk fat % was lower for cows receiving M (3.42 %) and the control (3.62 %) when compared to treatment V+M (3.86 %) (P<0.10). Milk protein and MUN did not differ. Body weight loss for the period from calving until day 60 postpartum, tended (P<0.15) to be less for cows receiving V+M (-8.1 kg) when compared to the control (-34.2 kg) and M (-31.9 kg) treatments. Both treatments M and V respectively, decreased blood BHBA and treatment M increased blood glucose (P<0.10) when compared to the control diet. Results suggest a complementary effect between the two additives monensin and virginiamycin when supplemented to early lactation cows. / Dissertation (MSc(Agric))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted

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.

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