摘要:

Genetical and economical consequences of different breeding programs for laying hens were simulated with percent residual food consumption (PRFC) included in multi-trait selection indices. The breeding program was calculated to be 17% more efficient when PRFC was included in the sire and dam indices based on all available sources of information, compared with no information on food consumption. Records of food consumption on hens only are expected to be somewhat cheaper and almost as efficient as recording on both sexes (14%). A less expensive method, but one also calculated to be significantly less efficient (4%), is to record PRFC exclusively on cocks. The efficiency of the breeding program was calculated only to increase by 2% when preselecting for food consumption in very young chicks, and the correlated selection response in PRFC was much lower than the other alternatives discussed.

ISSN:0906-4702    

DOI:10.1080/09064709209410111

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Lifetime economic performance traits were calculated from production, fertility and disease data on around 67 000 dairy cows with first calvings from 1982 to 1988. Almost 95% of the variation in lifetime income and cost was due to milk income or feed cost. The relative risk of culling (hazard) was maximum at approximately yearly intervals starting at 10 months of productive life. All lifetime economic traits were strongly affected by the length of productive life. The increase in, especially, lifetime net income per year, but also in lifetime income divided by cost with increased productive life, was highly curvilinear. This resulted from the spreading of the large heifer cost over an increasing productive life. When productive life exceeded two lactations the increase was smaller and fairly linear. A higher age at first calving was associated with lower lifetime economic performance, even though productive life increased slightly. The effect of month of first calving on lifetime economic traits was similar to its effect on milk yield. Considering various characteristics, lifetime income divided by cost seems to be the best trait for use as a single trait in the breeding goal.

ISSN:0906-4702    

DOI:10.1080/09064709209410112

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The appropriateness of the current adjustment factors for weaning weight was studied on data from the Swedish Sheep Recording Scheme for the years 1981–83 and 1986–88. The study included the four main breed groups Swedish Peltsheep (P), Swedish Landrace (L), Swedish Crossbred (X) and the imported heavy breeds (K). The adequacy of the adjustment factors was also tested within the breeds Swedish Finewool (Lf), Swedish Rya (Lr) and Crossbred group having crossbred parents (X*X). Analyses (1981–83) were based on 140681 Pelt lambs, 16785 lambs from the L-group, 25092 lambs from the X-group and 6321 lambs from the K-group. Data from 1986–88 comprised in total 11% fewer lambs.

ISSN:0906-4702    

DOI:10.1080/09064709209410113

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The aim of this study was to determine whether adjustment factors for lamb weight (covering ewe age, litter size, sex and lamb age) should be different for different types of flocks. The appropriateness of using common adjustment factors for all flocks was studied with respect to interaction between the adjusted effects and with region, flock size and production level. The survey was based on data from the Swedish Sheep Recording Scheme from the years 1981–83, comprising the main breed groups Swedish Peltsheep (P), Swedish Landrace (L), Swedish Crossbred (X), the imported heavy breeds (K) and some minor breeds Swedish Finewool (Lf), Swedish Rya (Lr) and Swedish Crossbreds with crossbred parents (X*X). Interactions with region revealed that ram lambs (P, L, X) and lambs born to one-year old ewes (P and X) were in general given slightly too high adjusted weights in the northern part of Sweden. K-Group ram lambs tended to be slightly favoured in the western region. The adjustment factors were appropriate in the average flock size, while lambs after one-year old ewes and ram lambs were in most cases given slightly too high adjusted weights in small flocks. In Peltsheep the adjusted weights for triplets were significantly too high in large flocks. Significant interaction effects were found predominantly between production level and ewe age and between production level and sex which resulted in too high adjusted weights for lambs after both one- and two-year old ewes and for ram lambs in flocks with high production level. Interaction effects in the Lf-, Lr- and X*X-breeds were seldom observed and did not deviate from their respective breed groups. The results of this study do not motivate special sets of adjustments which consider region, flock size and production level.

ISSN:0906-4702    

DOI:10.1080/09064709209410114

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The objective was to investigate the influence of ration energy concentration at the same feeding level on mammary growth, hormone secretion and subsequent milk production capacity of dairy heifers. Two groups of 19 Red Danish heifers were given the same amount of net energy in diets with either low or high energy concentration from 3 months of age. The average daily gain (ca. 500 g) was similar at the two diets. Nine heifers from each group were designated for slaughter at different live weights (range 139–383 kg) for estimation of mammary growth. Compared at the average body weight at slaughter (250 kg) the least-square means of mammary gland weights, extra-parenchymal tissue weights and parenchymal tissue weights of the groups fed low and high energy density rations were 1201±79 vs. 1162±84 (p>0.20), 789±63 vs. 698±67 (p>0.20) and 412±44 vs. 464±47 (p>0.20), respectively. In line with this there was no significant difference in the amount of milk produced by the cows raised on a low or high energy diet (16.7±1.0 vs. 16.8±1.0 kg 4% fat corrected milk;p>0.20). The amount of mammary parenchyma increased linearly with live weight (b= 3.08 g;P<0.001). Plasma concentrations of growth hormone, insulin or prolactin were not significantly affected by treatment. Plasma growth hormone concentration was positively correlated with amount of mammary parenchyma (r=0.61;p<0.01). From the results it can be concluded that mammary growth and milk production capacity in heifers is unaffected by ration energy density when the heifers are raised at a low feeding level.

ISSN:0906-4702    

DOI:10.1080/09064709209410115

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Long-chain fatty acid metabolism in the digestive tract was 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 low feed level (L0, L4 and L6), and 0, 2, 4 and 6% fat at high feed level (H0, H2, H4 and H6). Mean fatty acid balance from mouth to duodenum was about zero when corrected for endogenous fatty acids from bile. However, regression analysis showed a microbial synthesis of 68 g at zero fatty acid intake, and a trend which indicated declining de novo synthesis of fatty acids with increasing fat level in the diet. As a mean 68% of the unsaturated C18 fatty acids were hydrogenated in the rumen.

ISSN:0906-4702    

DOI:10.1080/09064709209410116

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Fatty acid digestibility was studied with five lactating cows fed three different fat sources in a 5 × 5 latin square experiment. The treatments were 500 g of tallow, 500 or 1000 g of saturated fat rich in stearic acid (C18:0) (SARF) or 500 or 1000 g of saturated fat rich in palmitic acid (C16:0) (PARF) per day. The total daily fatty acid intake was about 1100 g in rations with the highest fat inclusion. The fatty acid digestibilities were 76% for tallow, 74 and 64% for 500 and 1000 g SARF, respectively, and 87 and 81% for 500 and 1000 g of PARF, respectively. When compared to fatty acid digestibility for tallow predicted from a model based on literature values, PARF had a higher fatty acid digestibility at both fat intakes, and SARF had a lower fatty acid digestibility, especially at high fat intake.

ISSN:0906-4702    

DOI:10.1080/09064709209410117

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The objective of this paper is to describe the random variation in voluntary dry matter intake (VDMI) and to discuss the application of the results for monitoring purposes. Furthermore, the objective is to review and quantify the influence of day length or photoperiod on VDMI. VDMI was recorded in fifteen bulls, steers and heifers, respectively, fed a complete diet ad libitum. The diet was based on chopped straw formulated to secure physical regulation of feed intake. Total random variation of recorded VDMI corresponded to a coefficient of variation (CV) of 24.6%. Two thirds of this variation was due to random day to day variation in VDMI. Random variation between weeks, random variation between animals and residual random variation corresponded to a CV of 3.6, 8.0 and 10.0%, respectively, and they explained 2.5, 12.2 and 18.8% of the total random variation. In the present experiment VDMI was increased by 0.32% per hour increase in day length. This is in agreement with the increase found in reviewed literature when photoperiod was manipulated artificially. Practical application of the results for monitoring purposes are exemplified and discussed.

ISSN:0906-4702    

DOI:10.1080/09064709209410118

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:10.1080/09064709209410110

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor