SYNOPSISData pertaining to a closed White Leghorn flock maintained at the Punjab Agricultural University were used for estimating genetic and phenotypic parameters for age at first egg and 70-d egg production and also to evaluate the expected response to different methods of selection. Records of 2377 pullets, a progeny of 1001 dams and 155 sires over a period of two years, were used. The birds in this flock attained sexual maturity on an average at the age of 176.6 d and produced on an average 33.6 eggs in first 70 d of egg production.Heritability for age at first egg and 70-d egg production was obtained from different observational components. Age at first egg was found to have a medium heritability, the estimates being 0.370 ±0.003, 0.080 ±0.016 and 0.224 + 0.040 from sire, dam and full sib components, respectively. The heritabilities for 70-d egg production were low. The estimates were 0.132±0.004, 0.214±0.011 and 0.173±0.06 from sire, dam and full sib components, respectively. Phenotypic, genetic and environmental correlations were also obtained from analysis of variance and covariance. These two traits were found to be highly genetically negatively associated (-0.554 ±0.007). Phenotypic and environmental correlations between these two traits were also found to be negative and very low.An index incorporating age at first egg and 70-d egg production with 1.5 times negative weightage to the former was found to be two times more effective in reducing the age at first egg and 2-3 times more effective in increasing the 70-d egg production as compared to direct selection for the two traits individually.
Studies on the effect of body weight at calving on body-weight losses during early lactation and the post-partum reproductive performance of large, medium and small buffaloes revealed that the large buffaloes (weighing more than 550 kg at calving) lost most weight (45-9 kg) and the small buffaloes (weighing less than 475 kg at calving) least weight (4-9 kg) during the first 5 months of lactation. The body-weight loss was maximal in the 1st month of lactation. The reproductive performance (measured as conception rate, number of services per conception and service period) of small buffaloes was significantly (P < 0-05) better than the large buffaloes. These results indicate that body-weight losses during early lactation are affected by the body weight at calving and these losses play an important role in influencing the post-partum reproductive performance. It is therefore suggested that, to improve the reproductive performance, the feeding regimen of buffaloes during pregnancy and after calving should be such that body-weight losses after calving are small.
Three groups of buffaloes were fed with 20, 100 and 400mg of p,p'-DDT in their daily rations. The DDT residues in the milk fat of the treated animals showed an initial rapid rise but soon attained a dose-dependent equilibrium. The transfer coefficient of DDT residues in milk at 'plateau' levels showed an average value of about 12%. Half-life values for the rate of decline of DDT residues during the post-dosing period were computed according to a two-open-compartment model.
SUMMARYEight hundred and ninety-eight records of the interval between calving and conception (service period) of 349 Hariana cows, the progeny of 79 sires, were analysed by fitting constants for the effects of year, month of calving, calving sequence, sex of the calf, weight of the cow at calving and weight of the calf at birth. The average service period was 272·7 days with a coefficient of variability of 50·7%.The service period was longest after the first calving. Animals calving in the months of February to August had a longer service period than those calving during the months of September to January. Heavier cows tended to have a shorter service period. Sex of the calf, calving sequence and birth weight of the calf did not affect this trait significantly.Heritability of service period estimated from the paternal half-sib correlation using repeated records was 0·06 ± 0·018 and repeatability was 0·250 ± 0·039. It seems likely therefore that a shortening of the service period may not be possible through direct selection.
Zusammenfassung Die Verteilung von Spurenelementen im Blut, Plasma und in den Erythrocyten von Büffelkälbern (Bubalus bubalis) in der Neugeborenenphase Es wurden Spurenelementstatus und ‐verteilung im Blut, Plasma und in den Erythrocyten bei Büffelkälbern von der Geburt bis 15 Wochen nach der Geburt gemessen. Die mittleren Gehalte an Eisen, Zink, Kupfer, Kobalt, Mangan (μl/dl) im Blut, Plasma und in den Erythrocyten betrugen zur Zeit der Geburt 2547 ± 58.9, 445.2 ± 61.6, 68.3 ± 3.6, 0.88 ± 0.05, 34.3 ± 2.2, 397.4 ± 29.2, 268.3 ± 36.7, 63.2 ± 5.4, 0.85 ± 0.06, 36.2 ± 1.9 and 5074 ± 186, 591.2 ± 91.9, 80.5 ± 4.5, 0.99 ± 0.10, 37.8 ± 4.7. Die höheren Zinkkonzentrationen, die bei neugeborenen Büffelkälbern in den Erythrocyten beobachtet wurden, können auf einen aktiven Konzentrationsmechanismus oder einen mangelhaften Exkretionsmechanismus für Zink bei neugeborenen Büffelkälbern hindeuten. Aus den Untersuchungen geht ferner hervor, daß zwischen Plasma und Erythrocyten ein Austausch von Spurenelementen stattfindet. Zur Feststellung des Versorgungsstatus mit Spurenelementen scheinen Analysen von Blut, Plasma und Erythrocyten einen besseren Anhalt zu geben als die Analyse von Blut und Plasma allein.
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