摘要:

Stochastic simulation was used to assess the suitability of alternative dependent variables in international sire evaluation. Three such variables were considered: daughter yield deviations (DYD), national proofs (ETA), and de-regressed national proofs (DPRF). Data from two dairy cattle populations considering 10 generations were simulated. Genetic ties necessary for a joint evaluation of the two populations were established with bull exchange in each generation. De-regressed national proofs were the best and ETA were the worst in estimating genetic difference between the two populations and ranking bulls across country. Further, de-regressed national proofs can be easily computed and, contrary to DYD, are always available. De-regressed national proofs are recommended as dependent variables in across country sire evaluation.

ISSN:0906-4702    

DOI:10.1080/09064709509413079

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effects of culling of pigs before field performance testing was analysed using a stochastic simulation of a pig breeding unit with 100 sows and 15 boars. Ten years of data were generated for age at test (AGE) and sidefat thickness (FAT). Culling was performed at random (C-RAND), within litters (C-W/IN) or over litters (C-OVER), by deleting records according to the phenotypic value of AGE in the complete dataset. Genetic evaluations in the subsets of data were compared with the results in data with no culling (C-NO). For C-NO and C-RAND there was a good agreement between the true (TBVs) and predicted breeding values (PBVs) for both traits. In C-W/IN and C-OVER the PBVs were less favourable than the TBVs for AGE. C-OVER also showed a small effect on PBVs for FAT and on litter effects for AGE. Correlations between PBVs from models with or without a litter effect were .94 for C-NO and C-OVER, .97 for C-RAND and .98 for C-W/IN in the case of AGE, whereas for FAT they were all above .98.

ISSN:0906-4702    

DOI:10.1080/09064709509413080

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Litter sizes at birth and at weaning were analysed for the three most common breeds in the Swedish sheep recording programme. Lambing records for 124 571 Swedish pelt ewes (P), 8140 Svea breed ewes (X) and 3299 Swedish landrace finewool ewes (F) were broken down into subsets by parity. Parities 1 to 5 for P ewes, 1 to 4 for X ewes and 1 to 3 for F ewes were analysed with a linear mixed model that included random effects of flock-year and sire of the ewe and a fixed effect of sire birth-year class. When the non-linear threshold model was used on the same material, the fixed effect of thresholds was added to the above effects.

ISSN:0906-4702    

DOI:10.1080/09064709509413081

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effect of feeding level and nitrogen source on mammary development and plasma hormone levels of pre-pubertal (86 to 220 kg) Finnish Ayrshire heifers was studied. The treatments were: (1) LU, low feeding level + urea; (2) LR, low feeding level + rapeseed meal; (3) HU, high feeding level + urea; (4) HR, high feeding level + rapeseed meal. The average daily gains of the heifers on LU, LR, HU and HR diets were 692, 655, 805 and 890 g, respectively. There was a significantly higher amount of mammary parenchymal tissue and parenchymal DNA at low (L) compared with high (H) feeding levels, but no difference in mammary weights between nitrogen sources was found. Plasma insulin concentration was greater at H compared with L feeding levels, but plasma growth hormone (GH), insulin-like growth factor-I (IGF-I) and prolactin concentrations were not significantly affected by the feeding level. The amount of mammary parenchymal tissue did not correlate with the mean plasma concentration of prolactin and insulin. Also, no significant correlation between plasma GH (r= 0.32;P< 0.15) or IGF-I (r= 0.37;P< 0.09) and mammary growth was found. However, when GH measurements around feeding (2 h) were excluded, mammary development was positively correlated to plasma GH (r= 0.44;P< 0.05).

ISSN:0906-4702    

DOI:10.1080/09064709509413082

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Digestibility, energy metabolism and nitrogen utilization of a barley-based diet with increasing inclusion of lucerne leaf meal (LLM; 0, 5, 10 and 20%) were studied in a change-over experiment with growing pigs. In addition, digestibility and nitrogen utilization of the diets were evaluated with rats. The apparent digestibility of fibre increased with LLM inclusion, whereas the digestibility of organic matter, crude protein, fat and energy all decreased significantly. There was a significant reduction in the dietary content of digestible and metabolizable energy with increasing inclusion of LLM in the diet. Nitrogen retention and utilization were significantly increased with an increasing inclusion of LLM.

ISSN:0906-4702    

DOI:10.1080/09064709509413083

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

High-moisture barley was preserved anaerobically by ensiling using different additives, aerobically with propionic acid, or by drying. Chemical composition, feeding value and effect on physiological parameters in broiler chickens were studied. The content of true protein, total amino acids, total β-glucans and the viscosity were reduced when barley was stored in the moist stage. Anaerobic storage, which produced lactic acid and ethanol by fermentation, caused the strongest reduction. High-moisture barley reduced feed:grain ratio compared with dry barley, the difference being significant (p< 0.05) for the anaerobically stored barley in one experiment. Feeding high-moisture barley tended to reduce the relative weight of the digestive tract, and owing to less sticky droppings the cleanness of the cages and feathers was significantly improved (p< 0.05).

ISSN:0906-4702    

DOI:10.1080/09064709509413084

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Plasma growth hormone (GH) secretory profiles of 8-week-old male and female broiler chickens selected for high body weight at 42 days of age (GL line) or for improved food efficiency between 18 and 39 days of age (FCR line) were compared. A pulsatile GH secretory pattern was still present for all the 8-week-old chickens examined. Overall mean GH levels, and to a lesser extent GH baseline and GH amplitude values, were higher for FCR chickens compared with GL chickens. Mean GH concentrations, baseline and amplitudes were slightly, but not significantly, superior in males. Length and frequency of pulses were not influenced by line or sex. In view of the current knowledge on age- and sex-related changes in pulsatile GH secretion, it is argued that the line and sex differences would have been more pronounced in younger chickens. Based on this, the hypothesis that the amplitude of the pulsatile GH release is related to protein conversion efficiency and protein deposition rather than to average body weight gain is corroborated.

ISSN:0906-4702    

DOI:10.1080/09064709509413085

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Indicators of stress, behaviour in the pen, and lesions of the integument were used as indicators of sow well-being in a comparison of group housing with electronic sow feeding [GH] and confinement in gestation crates [C] in experiment 1, which included 2 × 4 groups of 20–25 sows. Effects of earlier experience with a gestation system on the indicators of stress was investigated in experiment 2, which included 2 × 3 groups of 20–25 sows. Reaction in a novelty test and reactivity in plasma Cortisol to the procedure of blood sampling were used as indicators of stress. Behaviour in the pen as well as lesions of the integument revealed that both gestation systems were suboptimal in some manner. However, following acclimatization for 1–2 weeks, young GH sows experienced less stress than young C sows as measured by reduced fear in the novelty test. In experiment 2 this interpretation was further supported by lower reactivity in plasma Cortisol. It was concluded that sow well-being was higher for the majority of the gestation period in young group-housed animals. Thus, in spite of the inadequate feeding method, well-being of sows may be improved in group housing systems with electronic sow feeding if the system is well functioning with low levels of aggression and vulva bites. One of the major determinants of vulva biting is suggested to be the mechanism of gate control.

ISSN:0906-4702    

DOI:10.1080/09064709509413086

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Ninetysix pigs, half females and half castrated males from 12 litters, were housed in 24 groups of 4 litter mates (2 females, 2 castrates). The pigs were weaned at 4 weeks of age and from the age of 115 days half of the groups were subjected to a schedule of unpredictable, inescapable electroshocks for 33 days, and half served as control. The adrenocortical reactivity to ACTH stimulation and to an emotional stressor (the procedure associated with initiation of blood collection) was measured in females, whereas the behavioural and pituitary-adrenocortical reactivity to an open field test was measured in castrates, as was the behavioural reactivity in a social test. Intermittent stress increased adrenocortical reactivity to ACTH stimulation significantly. This effect was present within the first week of intermittent stress (p< 0.06), but no difference was found after 4–5 weeks of stress. In contrast, the adrenocortical reactivity to additional emotional stressors was unaffected by stress after one week of intermittent stress, but increased after 4–5 weeks. In the open field test, centre location increased after one week of intermittent stress, whereas exploration decreased and walking and ambulation increased after 4–5 weeks of stress. In addition, 4–5 weeks of intermittent stress decreased aggressiveness in a social test. In conclusion, the change in reactivity to an additional acute stressor during intermittent stress appeared in different variables and contexts at different times during the course of intermittent stress. Thus, assessment of stress based on changed reactivity has to include several distinct measures of behavioural and hormonal reactivity.

ISSN:0906-4702    

DOI:10.1080/09064709509413087

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In two trials, production, feed consumption, mortality, egg quality and birds' live weight of a total of 2877 caged laying hens of four hybrids, Dekalb XL, Lohmann Selected Leghorn (LSL) and Shaver 288 in Trial 1 and ISA Brown and LSL in Trial 2, were studied during full production cycles. The cage designs were Get-away cages (GA) with 15 hens per cage, a special version of the “Edinburgh modified cage” called “Modified and enriched cage” (ME) with 4 ISA or 5 Leghorn hens per cage, conventional cages of metal (CO) with 4 hens per cage and conventional cages of plastic (PL) with 3 hens per cage. GA and ME included nests, perches and sandbaths. LSL produced significantly better than the other hybrids. Shaver had a significantly lower live weight than Dekalb and LSL, while ISA was significantly heavier than LSL. Production in ME was similar to that in conventional cages and, in Trial 2, birds in ME, CO and PL produced significantly better than those in GA. The highest mortality was registered in GA, where in Trial 2 it was significantly higher than in ME. GA gave a significantly higher and CO a lower proportion of cracked eggs than ME and PL. In both trials ME gave significantly lower proportions of dirty eggs than GA and in Trial 2, the lowest. Few differences between the systems were registered regarding interior egg quality. It was concluded that ME is better for production, mortality and management than GA but similar to conventional cages.

ISSN:0906-4702    

DOI:10.1080/09064709509413088

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor