摘要:

In assessing single gene effects on a quantitative trait, contrasts between the genotypes would be of primary interest. However, only the net differences over and above the contributions from polygene effects from other loci would be of practical importance. In a population of 11015 Holstein cows, the B allele ofK-casein was significantly favourable for milk and protein yields and for protein %, and the A allele of β-lactoglobulin was favourable for fat % and protein yield. The degree of dominance for their effects was shown. Also shown were the independence between effects of the casein variants and those of polygene, and between effects of casein genes. Adjustment for casein gene effects made no difference to the estimates of heritability and other genetic parameters of all five dairy production traits.

ISSN:0906-4702    

DOI:10.1080/09064709209410101

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The aims of the present study were to investigate the relationship between sexual maturation, growth and carcass performance in gilts. The incidence of malformations of the genital organs at slaughter was also recorded. The study included 360 Swedish Yorkshire gilts slaughtered at 102 kg live weight from a selection experiment for lean tissue growth rate. Of the 325 gilts used in the analysis of carcass performance, 164 were immature, 104 prepuberal and 57 sexually mature according to their ovarian morphology. No significant differences in growth rate were found between the groups. The carcasses of the immature gilts had a significantly greater lean content, regardless of the measurement method used, than the carcasses of the sexually mature gilts. The carcasses of the prepuberal gilts ranked between these two groups. Malformations of the genital tracts were found in 51 gilts (14%).

ISSN:0906-4702    

DOI:10.1080/09064709209410102

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

With the aim of studying the correlation between food consumption in very early life (0–5 weeks) and percent residual food consumption (PRFC) in laying hens, recorded from 16 to 40 weeks of age, a chick experiment was carried out. The experimental chicks were from a two-directional selection experiment, in which a duplicate hatch to the second generation was performed. Two of the lines in the selection experiment were developed for low PRFC and one line for high PRFC. Mean PRFC in the chick experiment were in close accordance with the mean PRFC of the corresponding lines in the selection experiment. There was significantly higher food consumption in the first 5 weeks of age in the high PRFC line compared to one of the low PRFC lines. Moderate phenotypic correlations were found between early food consumption and PRFC as adults, which theoretically permit the possibility of using food consumption in very young chicks as a selection criterion when preselecting for PRFC.

ISSN:0906-4702    

DOI:10.1080/09064709209410103

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Percent residual food consumption (PRFC) was recorded for cocks from a highly productive strain of layers and compared with PRFC recorded for old hybrid hens. In addition, possible causal traits to PRFC were studied on the cocks. PRFC is defined as the difference between the recorded and the expected food consumption as a percent of the expected. The phenotypic variation in PRFC among cocks was found to be large (SD=6.19%) and the heritability of PRFC was estimated to be 0.37 ± 0.29. Factors causal to the variation in PRFC were differences in fat content, behavioural pattern and heat loss in metabolic processes. Including PRFC, recorded on cocks in one four-week period after 24 weeks of age, as a selection criterion in an index may be suggested to improve the efficiency of food utilization in layers.

ISSN:0906-4702    

DOI:10.1080/09064709209410104

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A total of 730 dark mink, half of each sex, representing 94 paternal progeny groups originating from 16 farms were housed on a test station from about 10 weeks of age until pelting. Average daily feed consumption in paternal progeny groups was registered daily. Individual body weights were recorded five times. Feed consumption, feed efficiency and weight gain in paternal progeny groups were calculated in four subperiods corresponding to the times of weighing. These traits, body weights and length of pelts were analysed for differences between paternal progeny groups and farms of origin. A considerable difference between farms of origin and paternal progeny groups was found for most traits, indicating genetic variation. Correlations between averages of paternal progeny groups were calculated, and interpreted as approximations to genetic correlations. Feed consumption was highly correlated across periods. Feed efficiency showed low to medium correlations between periods. A favourable correlation was found between efficiency of weight gain and efficiency of longitudinal growth.

ISSN:0906-4702    

DOI:10.1080/09064709209410105

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Dietary protein degraded to various extents by varying the time of rumen incubation was prepared from eight concentrates and four roughages. Intestinal digestibility was obtained using the mobile bag technique on intact protein and on the samples of undegraded dietary protein from each feed. The results showed that increased degradability of the protein in the rumen decreased the intestinal digestibility, which shows that feedstuffs contain a protein fraction which is both undegradable in the rumen and indigestible in the intestine. The results thus indicate that it is possible to calculate the intestinal digestibility from information on the intestinal digestibility of the protein in the intact feed at any degradability estimated. The results clearly show that intestinal digestibility of undegraded dietary protein cannot be considered as a constant value as used in most protein evaluation systems introduced in recent years.

ISSN:0906-4702    

DOI:10.1080/09064709209410106

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The effects of sex and pregnancy on feed intake capacity in growing cattle were studied in an experiment with fifteen bulls, steers and heifers, respectively, and designed with complete randomized blocks. All sexes were fed ad libitum with a complete diet based on chopped straw from three months of age to approximately 520 kg. At live weights below 250 kg heifers had higher feed intake capacities (IC) than bulls, and IC of steers was intermediary. Above 250 kg live weight sex differences in IC were small and not significant. The results support the hypothesis that early maturing animals (heifers and steers) have a higher IC than late maturing animals (bulls) at low live weight. Gestation decreases IC during the last 14 weeks of pregnancy and IC was depressed by 1.5% per week. During the last couple of weeks before calving the depression in IC may be even higher. The depression in IC is due to both physical limitation of the reticulorumen and gastrointestinal tract and hormonal regulation.

ISSN:0906-4702    

DOI:10.1080/09064709209410107

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An objective system for beef carcass classification (BCC) will be available shortly. Thus, payment based on objective parameters becomes possible. Alternative pricing systems were tested on the basis of carcass composition data and visual gradings from 403 bulls. Carcass dissection data were converted into a Danish commercial cutting standard to simulate results from an objective beef classification centre. Data represented progeny of Red Danish and Danish Friesian cows sired randomly with one of the following breeds: Angus, Charolais, Gelbvieh, Piemontese, South Devon, Brown Swiss, Red Belgian, Blue Belgian, Red Danish or Danish Friesian. Bull calves were allotted at 70 d of age to three target slaughter weights (320, 440 and 560 kg) and three feeding levels (ad lib., 85 and 70% on an energy basis). The present Danish pricing system, based on EUROP grading, was compared to an alternative pricing system based on yield of saleable meat, a muscularity index, fat trim and fat/lean colour. Compared with the conventional pricing system, the most marked difference of the alternative system was that carcasses with a high percentage of saleable meat and a high muscularity index receive price additions whereas carcasses with surplus fat receive price reductions. Early matured crossbreds with high fat deposition were downgraded, whereas muscular crossbreds were upgraded. The gross margin per day was subsequently strongly dependent on the pricing model, thereby changing the optimal production strategy.

ISSN:0906-4702    

DOI:10.1080/09064709209410108

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Ninety dried raw blue fox skins having two different dietary backgrounds, saturated fat and fish fat feeding, were submitted to the following experimental treatments: dressing after pelting; control storage at 8 [ddot]C or at -20 [ddot]C; antioxidant diet, storage at 8 [ddot]C or at -20 [ddot]C; butylhydroxytoluene (BHT) drumming, storage at 8 [ddot]C or at -20 [ddot]C; nitrogen gas, storage at 20 [ddot]C; and pickling, storage at 8 [ddot]C. Each storage group contained five skins from both dietary groups. Storage duration for the dried raw skins was approximately one year, during which the changes in their fatty acid compositions were analysed. After the storage period the skins were dressed and the physical characteristics of the leathers were determined.

ISSN:0906-4702    

DOI:10.1080/09064709209410109

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:10.1080/09064709209410100

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor