No description available.

No description available.

Efficacy of a sustained-release formulation of bST was evaluated for two consecutive lactations. Response in milk and milk component yield was positive and very consistent for multiparous cows between lactations. Average responses in milk production for the first lactation and for the 320-, 640-, and 960-mg$ cdot$28d$ sp{-1}$ doses of bST were 4.3, 5.2 and 5.9 kg$ cdot$d$ sp{-1}$, respectively. Response was 4.9 kg$ cdot$d$ sp{-1}$ for the average of the second lactation with 640 mg bST$ cdot$28d$ sp{-1}$. Primiparous cows responded with the same numerical magnitude as multiparous cows but with higher variability. BST caused a response in milk yield irrespective of the stage of lactation when injections commenced, but the magnitude of response was greater at latter stages of lactation. No adverse effect of treatment on final body condition score and achievement of proper condition for a subsequent lactation was found. No effect of treatment was observed on health parameters in either lactation. Trends towards longer days open and more breedings per conception were apparent for both lactations. Total milk protein, caseins and whey proteins were not changed at any stage of lactation and for the average of the full lactation. BST did not significantly change proportions of $ alpha sb{s}$-, $ beta$- and K-caseins. Milk fat percentage and milk fatty acid profiles were not different between control and any dose level of bST for a complete lactation. Maximum response in milk yield for the different doses of bST was from d8 to 12 of the 28d cycle and was almost eliminated by d22 to 24. A 3.1 and 3.6 kg$ cdot$d$ sp{-1}$ milk augmentation with bST was estimated in cows infused for 6d with glucose and saline, respectively during peak lactation. There was no apparent milk yield response when cows were infused with insulin + glucose but cows exhibited positive energy balance, weight gain and only 5% less milk. Insulin + glucose infusion increased milk protein 11% and 14% compa

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Dairy cows fed diets supplemented with 2.5% calcium-salt fatty acids (CSFA) (DM basis) during early lactation produced more 4% FCM than cows fed the control diet. Feeding this diet also increased whole lactation performance. Supplementing diets with 1.25% CSFA or animal fat did not increase production performance of cows. Dietary fats were used directly for greater milk production and, based on unchanged body condition scores, did not alleviate body fat mobilization. Changes in the milk fat content and composition due to fat supplemented diets were negligible. A slight decrease in milk protein and SNF percentage was observed with CSFA but not with animal fat feeding. Palatability of the diets was good and DM intake was not impaired. Feeding animal fat at 1.25% and CSFA up to 2.5% of the DM does not impair forage digestibility and nitrogen balance. Dietary fat increased plasma triglyceride (TG) and cholesterol concentration. Injection of 10.3 mg d$ sp{-1}$ or 350 mg 14d$ sp{-1}$ of recombinant bovine somatotropin (rbST) did not change 4% FCM production or milk composition at any stage of lactation.

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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No description available.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1960 H32