摘要:

Fifty-seven calves from two lines selected for high (n= 36) and low (n= 21) milk fat yield were typed for a known restriction fragment length polymorphism (RFLP) in the growth hormone (GH) gene. The genetic origin of the RFLP is an insertion (I)/deletion(D) in the 3′-region of the growth hormone gene. The calves were tested at 3–4 months of age and again at 9–10 months of age for plasma GH concentration before and following three GH release tests: fasting-refeeding (n= 57), arginine injection (n= 28) and thyrotropin-releasing hormone (TRH) injection (n= 24). The RFLP typing showed 36, 19 and 2 calves of the genotypes II, ID and DD at the I/D site, respectively. The frequency of the D-allele was higher in the high than in the low selection line (0.29 vs. 0.05,P<0.01). At 9–10 months of age the GH release following TRH injection was larger in calves with genotype II (35.9 ± 4.5 ng/ml) compared with calves with genotype ID (23.6 ± 3.8 ng/ml) (P<0.05), and the calves from the high line had a higher GH release after TRH injection (42.9 ± 5.5 ng/ml) compared to low-line calves (19.7 ± 3.4 ng/ml) (P<0.001). These results may indicate that the I/D site may affect or be a genetic marker for TRH-induced GH release in dairy calves.

ISSN:0906-4702    

DOI:10.1080/09064709309410156

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In a selection experiment, halothane gene-free Swedish Yorkshire pigs were performance tested (25–90 kg) for improved lean tissue growth rate (LTGR) on two diets: high protein (HP 18.5 CP), and low protein (LP 13.1 CP). LTGR was estimated from ultrasonic measurements of fat and muscle depth and repeated weighings. 2885 pigs were tested in generation zero and four selected generations. The selection intensities were 17% for males and 54% for females. Genetic parameters were analysed with restricted maximum likelihood (REML) using a reduced animal model. Total response (phenotypic trend) was in HP +43 and in LP +25 g/day, and the genetic trend was HP +33 and LP +30 g/day. The heritability for LTGR was 0.37 in both lines. Reasons for the different rates of progress in the two lines are discussed.

ISSN:0906-4702    

DOI:10.1080/09064709309410157

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Litter sizes (LS) for the three largest breeds of sheep represented in the Swedish sheep recording scheme, Pelt (P), Swedish Crossbred (X) and Landrace Finewool (F), were studied. Average LS for different ewe ages were seen to increase from yearling to full maturity, around 4 years of age, and then remained the same until around 9 years of age for P and X, which thereafter showed a slight decrease. Landrace Finewool, a more prolific breed, peaked at 5 and 6 years of age and started to decline the year after. Flock size in itself did not significantly affect LS for any breed. The addition of an effect of flock-year increased the coefficient of determination (R2) in a linear model. SAS Proc CATMOD estimated noticeable differences between LS distributions for different breeds and ewe ages, and smaller differences between LS distributions for individual ewe deviations from flock average lambing date. It was concluded that the effects of flock-year and age of ewe were the major fixed effects that need to be accounted for when evaluating LS within breed.

ISSN:0906-4702    

DOI:10.1080/09064709309410158

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Genetic and non-genetic sources of variation were estimated within and between populations in a progeny testing scheme with approximately 200 paternal progeny groups of mink. Animals from several populations were housed at a central test station and corresponding full-sibs were kept at the farm of origin. Body weight was recorded in the production period, and the length of the dried skins was measured after pelting.

ISSN:0906-4702    

DOI:10.1080/09064709309410159

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Genetic and environmental sources of variation in skin and fur characteristics were estimated within and between populations in a two year mink progeny testing scheme with approximately 200 paternal progeny groups. Animals from several populations were housed at a central test station, and corresponding full-sibs were kept at the farm of origin. Data were analysed with an animal model to estimate heritabilities, common litter effects and fixed effects due to population and environment. Genetic variation within and between populations was found, together with significant environmental effects, indicating potential improvements in the breeding scheme. An interaction of sex with population and environment was considered and found significant for traits with a large sex dimorphism. Common litter effects were unimportant for traits measured, except for length and weight of skin. Discrete, subjectively measured traits are analysed with a linear model and a threshold model.

ISSN:0906-4702    

DOI:10.1080/09064709309410160

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Our objective was to examine the effects of bovine growth hormone (bGH) on growth, carcass composition and meat quality of dairy heifers. Nine monozygotic twin pairs of Friesian or Red Danish cattle were used, and pair-fed à diet consisting of grass silage, barley and soybean meal. Within each pair, one animal was given daily subcutaneous injections of 20 IU of pituitary-derived bGH (15–20 mg), while the other animal was injected with saline (excipient). Treatments started at 179±2 kg body weight and lasted for 15.6 weeks. At slaughter, carcass composition and meat quality were analyzed. bGH treatment increased gain by 8% (948 vs. 877 g/d;P<0.03). The amount of saleable meat in carcass and lean content of four main carcass cuts were on average increased by 2% (P<0.05). Concomitantly, carcass fat trim was reduced by 12% (P<0.001), fat trim of individual cuts by 4–21% (P<0.05), and kidney fat by 13% (P<0.01). Except for a 20% reduction of intramuscular fat content (P<0.001), meat quality assessed by objective as well as subjective methods was unaffected by bGH treatment. In summary, bGH treatment of dairy heifers around puberty stimulated growth and reduced carcass fattening including intramuscular fat, while eating quality of the meat was unaffected.

ISSN:0906-4702    

DOI:10.1080/09064709309410161

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In order to investigate the effect of age at weaning and the post-weaning environment on the behaviour and health of piglets, litters were weaned at 4 or 6 weeks of age and either kept in their farrowing pen or housed in flat decks (2 × 2 factorial design with a total of 24 litters). At 9 weeks of age all litters were moved to standard pens for fattening pigs. Behavioural observations and recording of lesions were undertaken at 8 and 12 weeks of age.

ISSN:0906-4702    

DOI:10.1080/09064709309410162

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A method is presented for estimating the value of increased weighing precision when selecting pigs for delivery to the slaughterhouse. A dynamic programming approach is taken using hierarchic Markov processes in combination with a probabilistic growth simulation model. A heuristic delivery policy is optimized. Pigs with observed live weight higher than a threshold weight are delivered for slaughter. The pen is emptied depending on the age and number of remaining pigs in the pen. The optimal delivery policy is relatively robust to variations in weighing precision. The value of high weighing precision decreases markedly with increasing number of pigs per pen and is generally low. With 16 pigs per pen the low value of improved weighing precision leaves little financial room for investment in weighing equipment.

ISSN:0906-4702    

DOI:10.1080/09064709309410163

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0906-4702    

DOI:10.1080/09064709309410164

出版商:Taylor & Francis Group    

年代:1993

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:10.1080/09064709309410155

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor