Two silages were prepared from mature orchardgrass ensiled at 19% dry matter. The additive NutroLac Sila-Aid, containing a dry culture, of lactobacilli, was added to one silage at a rate of 0.5 kg per tonne of fresh herbage, the other silage remained untreated. A wooden stave silo of 40-tonne capacity was filled with each silage. Silage effluent was collected daily for 30 days and the silage temperature was recorded daily for 2.5 months. These two silages comprised the only forage in a two-period crossover design feeding trial. The silages were fed ad libitum (10% feed refusal) and grain was fed at a rate of 1 kg per 3.5 kg milk yield. Twelve Holstein cows in early to mid lactation were subdivided in two groups and allocated to the treated or untreated silage. The cows were fed the assigned forage for a 7-day adjustment period and a 7-week experimental period. The treatments were reversed during a 7-day change-over period and the alternate forage fed for a further 6 weeks. Three cows from each group were assigned to a 7-day digestion trial for total collection of feces and urine during the second last week of each experimental period. The herbage ensiled had the same composition for both silos, the dry matter and protein contents being 19.0 and 14.4% respectively. The treated silage lost almost twice as much effluent compared to the control. Dry matter and protein loss accounted for 2.5 and 4.2% of the ensiled dry matter and protein in the treated silage and 1.5 and 2.3% in the control silage. Peak silage temperatures of 30.3 and 29.1°C for treated and untreated silage were recorded on the ninth day after ensiling. The resulting silage had a dry matter and protein content of 22.8 and 13.2% (treated) and 23.8 and 13.0% (untreated). There was no significant difference (P^.05) between the two treatments with regards to intake, body weight change and milk production. On the average the cows consumed 10.1 kg forage and 8.0 kg grain on a dry matter basis and yielded 2 28.0 kg milk containing 3.2% fat. The animals fed NutroLac silage gained an average of 3.7 kg per period whereas the cows on control silage lost 5.6 kg over the same time. The rumen pH and the acetate/propionate ratio of the ruminal fluid was the same for both treatments, the values being 6.6 and 2.4. The apparent dry matter digestibility of the total ration was significantly higher (P≤.05) for the control silage (70.7%) compared to the treated (69.1). The digestibility of organic matter and protein was not different (P≤.05) between treatments, the average being 7 3.3 and 74.4%. The results from the present experiment tended to be in favour of the control silage and indicated that there was no advantage, and perhaps even a disadvantage, in terms of dry matter digestibility and increased ensiling losses when NutroLac was added to the grass at ensiling time. / Land and Food Systems, Faculty of / Unknown

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Thirty six: Holstein bull calves were assigned to a 3X3 factorial design with ration physical forms of chopped hay (CH), ground hay (GR) and all concentrate (CONC) and rumen degradable nitrogen (RDN) of 30, 45 and 60%. Metabolic body weight, liver weight and blood glucose were greatest in CONC-fed calves. Neither dry matter nor ash content of liver tissue was affected by either physical form or RDN. Within physical form, protein content was highest and fat lowest in livers of CH-fed caIves. Within RDN, livers of calves feel 30% RDN rations had lowest protein and highest fat content. RDN percent had no effect on carbon dioxide production. Livers from CONC-fed calves produced significantly· (P<.05) more carbon dioxide from [1⁻¹⁴C}propionate and [U⁻¹⁴C}lactate.Glucose production from propionate and lactate was greatest for CONC-fed and 60% RDN-fed calves, although significant only from lactate within physical form. Interaction between ration physical form and RDN makes interpretation of propionate data difficult. In 30% RDN-fed calves both lactate and propionate metabolism was similar for GR- and CONC-fed animals. At 45 and 60% RDN rations, CONC- and CH-fed calves had similar gluconeogenic rates from propionate but glucose from lactate was significantly greater in livers of CONC-fed calves compared to GR- and CH-feet animals. Ten lactating and five dry Holstein cows were liver biopsied at various stages of lactation (30,60,90,120,180 days postpartum and dry) and when fed two rations, control ( 18% CF) or high concentrate (HI CONC, 10.5% CF). Lactating cows at 30 and 60 days and dry cows were fed the control ration. After 60 days half the cows remained on the control ration and half the lactating cows were changed to the HI CONC ration. Milk fat percent was depressed in cows fed HI CONC ration. Milk fat percent was depressed in cows fed HI COCC ration. HI CONC cows consumed more dry matter and due to the higher energy content reached a positive energy balance before control cows. Rumen fluid volatile fatty acid production was not affected by stage of Lactation or ration fed. Both plasma glucose and plasma insulin nonsignificantly increased as lactation progressed. Liver tissue protein did not change over lactation but increased when HI CONC ration was fed. Stage of lactation affected (P<.0002) propionate metabolism to carbon dioxide with higher production at 120 days compared to 180 days. By ration, HI CONC cows' livers produced more carbon dioxide than control cows’ livers. Feeding the HI CONC ration significantly increased labelled glucose production. Increased production of both labeled carbon dioxide and glucose by liver from cows fed HI CONC ration was nonsignificant when based on liver protein content. Carbon dioxide/glucose ratio was similar for lactating (>60 days) and dry cows. Cows early in lactation (30 days) had significantly lower carbon dioxide/glucose ratios, indicating a higher glucose production. Ration and stage of lactation are important factors in ruminant metabolism.. Gluconeogenesis, a pathway especially important in ruminants, is affected by both factors. In calves and cows, concentrate rations increased glucose production. Ration RDN, studied in calves, affected lactate metabolism to glucose. The liver of lactating cows showed a greater response (increase in glucose production) to stage of lactation than ration fed demonstrating the importance of energy balance on ruminant metabolism. / Ph. D.

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Digitized by Kansas Correctional Industries

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Twenty-five animals that were randomly selected on the basis of sex and age from among the animals feeding exclusively on communal grazing in Mogosane village and were used to investigate the mineral (P, Ca and Mg) status, especially P, based on blood and faecal P and to estimate the quantity of P they consumed from the pasture they were grazing. The project was conducted in the same area each month for one year, and no supplement was given. Months were blocks and seasonal changes were factors and the animals were experimental units within a block. Faecal, blood and grass samples were used as indicators of P, Ca and Mg minerals within experimental units, and Analysis of Variance was done to determine whether the P status of native pastures had a significant effect on the total P, Ca and Mg utilization and movement in and out of the blood and throughout the faeces during different periods the year. Body mass, condition scores and rainfall were also recorded during this trial. When the mineral status was investigated in this trial, it was found that mineral content in blood and faeces was directly related to the minerals in the pasture since these indicators were curvilinear increasing from winter months to spring months peaking in summer months with highly (P< 0.05) significant values when grazing was best and declining as the grazing became worse during autumn and winter months. The values of the body condition of the animals increased and declined with the values of body mass. Blood P concentration was very inconsistent and varied greatly and did not follow the same increasing and decreasing pattern followed by faeces and the grass. This emphasizes the fact that the P content of blood is not always good indicator of the P status in the animal. The mean faecal P concentration during winter was lower with the value of 1.23 ± 0.13 mg/g, during spring was low with the value of 1.8 ± 0.06 mg/g, during summer was higher with the value of 3.22 ± 0.12 mg/g and during autumn was high with the value of 1.98 ± 1.04 mg/g. The mean concentration of P in the grass during winter was lower with the value of 0.92 ± 0.04 mg/g, during spring was low with the value of 1.16 ± 0.08 mg/g, during summer was higher with the value of 1.68 ± 0.06 mg/g and during autumn was high with the value of 1.22 ± 0.09 mg/g. The seasonal rainfall correlated with the faecal and grass P values vary much with the value of 0 mm in the winter season, with the value of 26.33 mm in the spring, the value of 90.4 mm during summer and the value of 44.83 mm during autumn. Condition scores and body masses had the values of 2.08 units/201.4 Kg during winter season, had the values of 3.07 units/272.29 Kg in spring season, had the values of 3.88 units/371 Kg during summer season and the values of2.75 units/286.65 during autumn season, respectively. / Thesis (M.Sc. (Agric.)) --North-West University (Mafikeng Campus), 2005.

Four successive groups of four calves each (~ 4 mo old) were individually penned and observed during a 14 d trial period for choice of concentrate. Prior calf diets contained soybean meal (SBM) (for two groups and distillers grains in place of SBM for two groups. Concentrates contained approximately equal amounts of corn with either SBM, peanut meal (PNM), fish meal (FSM), or corn gluten meal (CGM). Each day of four trials, .45 kg of each concentrate was randomly assigned to one of four equal feed box sections. Calf feeding position was recorded every 30 sec for no more than 50 min or until calves stopped eating. In addition, 1.36 kg of first cutting orchardgrass hay was offered twice per day. Measurements of amount of each feed consumed, order of consumption and length of time spent eating each feed were analyzed statistically to determine preference. Overall preference was for SBM, closely followed by PNM, both over FSM and CGM, with the l preference status of FSM showing the most change over time by decreasing throughout the trial periods. Neither section in which feed was offered nor previous experience with SBM significantly influenced preference. In addition, twenty calves ranging in age from 4 mo to 7 mo were divided and housed in four groups of five and observed during a 30 d trial period for acceptability of the protein feeds tested for preference. Acceptability, measured subjectively as length of time required by calves to eat each feed, was greatest for SBM, closely followed by PNM and CGM, and least for FSM. Analysis of calf weight gain showed no differences between feeds. / Master of Science