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Effect of sometribove (methionyl bovine somatotropin) on mastitis in 15 full lactation trials (914 cows) in Europe and the US and 70 short-term studies (2697 cows) in eight countries was investigated. In full lactation studies, sometribove (500 mg/2 wk) was given for 252 d, commencing 60 d postpartum. Although herds varied considerably, incidence of clinical mastitis within a herd was similar for cows receiving control and sometribove treatments. Relative risk analyses indicated no treatment effect, and percentage of mastitis during treatment was similar for control and sometribove groups. A positive linear relationship existed between peak milk yield and mastitis incidence (percentage of cows contracting mastitis or cases per 100 cow days); sometribove treatment did not alter this relationship. Increases in mastitis related to milk yield increase from sometribove or related to genetic selection were similar. When expressed per unit of milk, mastitis incidence declined slightly as milk yield increased; this relationship was not altered by sometribove. No effect on clinical mastitis was observed in 70 commercial herds utilizing sometribove for 84 d. However, effects were significant for stage of lactation and milk yield. Overall, studies represented a wide range of research and commercial situations demonstrating that sometribove had no effect on incidence of clinical mastitis during the lactation of treatment. Furthermore, sometribove did not alter typical relationships between milk yield or herd factors and incidence of clinical mastitis.

In three 24-wk experiments beginning at wk 4 post partum, a system of concentrate feeding at a flat level was compared with feeding concentrates to milk yield (experiments 1 and 2), or with a high-low 2-step system in which the rate was reduced after wk 12 (experiment 3). Roughage was offered ad lib. In experiment 1 two types of concentrates were involved whereas in experiment 3 two levels of concentrates were applied. The systems were evaluated using high levels of concentrates and with Friesian and Holstein-Friesian cows producing about 7000 kg milk/lactation. Experiments 1 and 3 involved 64 and experiment 2 32 cows. In the comparison between feeding strategies, differences in yield and composition of milk were of minor importance except for milk protein content on the moderate-quality grass silage diet (experiment 1). Milk production tended to be higher for concentrates including fish meal, in contrast to soyabean meal, particularly in the first half of the experimental period. However, milk fat content was significantly lower, resulting in similar productions of 4%-FCM. Extra concentrates in experiment 3 had significant positive effects on the production of milk, fat and protein, and also on milk protein content and liveweight gain. Feeding strategy however, was without any significant effect. It was concluded that with the high-yielding cows, offered roughages to appetite, there is no need to feed concentrates strictly to their estimated individual energy requirements. This may be of increasing importance when forage allowances/cow increase as a consequence of smaller numbers of cows/farm. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Protein evaluation systems (crude protein (CP), digestible crude protein (DCP), protein digested in the intestine (PDI), amino acids truly absorbed in the small intestine (AAT), absorbed protein (AP), metabolizable protein (MP), crude protein flow at the duodenum (AAS) and digestible protein in intestine (DVE)) were validated using data from 15 production experiments with dairy cows, carried out in the Netherlands. Only treatments that were deficient in protein according to at least one system were selected. Average yield was 31.2 kg of fat and protein corrected milk daily and 989 g of milk protein daily. The observed milk protein production was compared with milk protein production predicted from the protein supply and requirements in each system. The difference between observed and predicted milk protein production expressed as the absolute and relative prediction error was smallest for the DVE-system (-2 g/day; 5.7%) and increased in the order CP (-22 g/day; 6.7%), PDI (-19 g/day; 7.8%), DCP (-44 g/day; 8.8%), AP(-37 g/day; 9.3%), AAS (100 g/day; 11.7%), AAT (112 g/day; 13.4%) and MP system (204 g/day; 22.9%). Predictions can be improved when a variable efficiency of milk protein production is used. In the DVE-system the observed efficiency decreased with increasing protein to energy ratio in the diet and milk production level. It was concluded that under Dutch conditions the prediction of milk protein production decreased in the order DVE, CP, PDI, DCP, AP, AAS, AAT and MP system.

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