摘要:

The aims of this study were (1) to estimate genetic parameters for some biological and economic measures taken early in life, and subsequent lifetime economic performance traits, and (2) to calculate the expected genetic gain in lifetime performance from selection based on various selection indices. The breeding goal traits were: net income per year of productive life and lifetime income divided by cost. The early economic index traits were: net income per year and income divided by cost, measured during the first lactation or the first 15 months of productive life. Economic traits were calculated on the basis of production, fertility, and disease data on around 10000 cows having an opportunity to produce for at least 5 years. Variance-covariance components were estimated by applying a multiple-trait restricted maximum likelihood procedure to a sire model. The heritability estimates were around 40% for yield in 1st lactation, 20–30% for the early economic measures, and 10–15% for lifetime income/cost. Genetic correlation estimates with lifetime income/cost were 0.75–0.9 for early economic measures, and 0.6–0.7 for 1st and 2nd lactation yields. The annual genetic gain in lifetime economic performance was greater with selection on only 1st lactation yields than when the generation interval was extended to include 120-day yields in 2nd lactation. However, selection on the various early economic measures was up to 12% better than selection on only 1st lactation yields. A potential problem with a positive bias in the estimated correlation between early and lifetime performance exists. This bias is caused by the effect of milk yield on longevity, mediated through the management system.

ISSN:0906-4702    

DOI:10.1080/09064709209410120

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Rumen metabolism, microbial biomass synthesis and microbial long chain fatty acid composition were studied in lactating cows fed at two levels of dry matter intake (L, 8.6 kg DM and H, 12.6 kg DM) with 0, 4 and 6% added tallow at the low feed level (L0, L4 and L6) and 0, 2, 4 and 6% at the high feed level (H0, H2, H4 and H6).

ISSN:0906-4702    

DOI:10.1080/09064709209410121

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Fatty acid digestion was studied in three dairy cows cannulated in the rumen, duodenum and ileum. Cows were fed encapsulated fat sources (vegetable oil, saturated fat and fish oil). A preperiod diet was fed with no added fat. In a graeco-latin design nine diets comprising three levels of each of the three fat sources were fed. The preperiod diet contained 230 g fatty acids (FA), whereas the three other fats were fed at about 550, 850 and 1150 g FA/day. The feed-ileùm true digestibility of total FA was 95, 47 and 86% for vegetable, saturated and fish fat, respectively. The true digestibility of FA was for all fat sources independent of fat level. The FA digestibility of C16:0 was higher than that of C18:0. The experiment supports the theory that unsaturated FA has a synergistic effect on the digestibility of saturated FA. Bile acid secretion was estimated to be 282–550 g/day, with the lowest secretion for fish fat diets. Secretion was independent of the amount of fat fed.

ISSN:0906-4702    

DOI:10.1080/09064709209410122

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Forty-eight Finnish Ayrshire bulls of average live weight 106 kg at the start and 432 kg at the end of the experiment were fed grass silagead libitumand restricted amounts of concentrates consisting of barley alone (treatment A), or barley supplemented with untreated 0-rapeseed meal (RSM-1, B), heat-moisture-treated (ÖPEX®) 00-RSM (RSM-2, C), untreated 00-RSM (RSM-3, D) or heat-moisture treated 00-RSM (RSM-4, E). RSM-1 and RSM-2 originated from black-seeded rapeseed varieties (Brassica campestris) and RSM-3 and RSM-4 from a variety with yellowish-coloured seeds.

ISSN:0906-4702    

DOI:10.1080/09064709209410123

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

510 group-fed bulls of the Swedish Red and White breed were used to investigate differences in production and health when housed either in an insulated building with slatted floors in the pens or in an uninsulated building with partly littered pens. Two stocking densities, 11 versus 15 animals/pen, were studied as well, but only in the uninsulated building. The animals were fed concentrate ad lib., 0.5 kg/d of roughage, and were slaughtered at about 220 kg live weight (bull calves) or at about 420 kg live weight (bulls). The comparison between buildings showed no significant differences either in feed intake or in live weight gain. Feed conversion, if calculated as MJ metabolizable energy/kg live weight gain, was significantly poorer for bull calves (but not for bulls) in the uninsulated building. If calculated as MJ metabolizable energy/kg carcass gain, there was no significant difference in feed conversion between animals in different buildings. Animals in the uninsulated building had less fat in the carcass than the others. Bull calves had significantly more liver abscesses in the insulated building than in the other. Bulls were treated for pneumonia and interdigital phlegmon more often in the uninsulated than in the insulated building. Animals in the uninsulated building had a higher energy requirement for maintenance and activity than the others. The main reason for this was probably the difference between buildings in area per animal and pen design. The higher stocking density resulted in a lower growth rate of the bulls.

ISSN:0906-4702    

DOI:10.1080/09064709209410124

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The influence of dietary protein, fat and mineral levels on crude fat and fatty acid digestibility was investigated in growing pigs. The experiment was a factorial design with two levels of protein (normal and high), two levels of dietary fat (3 and 15% of DM) and three levels of minerals (50, 100 and 150% of Danish Standard). Four litters, each of six female pigs, were used in the experiment.

ISSN:0906-4702    

DOI:10.1080/09064709209410125

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The relationships between scores for general appearance assessed in August and November and the size and quality of scanblack and pastel male pelts were studied. The size of pelt was more closely associated with general appearance graded in August than in November. The reverse situation was found for the quality of pelt. Fur defects observed in live minks reduced pelt quality. Size, quality and colour of pelts in scanblack males differed between farms, and in pastel males, differences between farms were found in pelt quality and clarity. The pelts of males with high scores in live animal grading were sold for 4–14 Finnmark more than medium or low scoring ones. Skin prices were more affected by the date of auction than by grading scores.

ISSN:0906-4702    

DOI:10.1080/09064709209410126

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue

ISSN:0906-4702    

DOI:10.1080/09064709209410119

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor