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Showing 2 results for Reproductive Performance

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Volume 5, Issue 3 (12-2016)
Abstract

In a randomly and factorially designed experiment, the interaction effects of dietary zeolite (0 and 2%) and three salinity levels (80, 130 and 180 ppt) on growth, survival, reproductive performance and total longevity of A. franciscana were determined (6 treatments in total). The experiment was carried in two stages: nauplius to maturity and maturity to death of all females. The results indicated that the total body length of Artemia fed with zeolite were not significantly different among treatments in the third week of rearing (P>0.05), except for nauplii fed zeolite in salinity 180 ppt. However, Artemia fed with zeolite in 80 ppt had a higher body length and furcal length compared with other treatments. Nauplii in all treatments reached sexual maturity within 17-23 days (P>0.05). Survival rate was far higher in groups fed with zeolite compared to unfed groups; the highest values were recorded in group fed with zeolite at the salinity 130 ppt (P<0.05). The reproductive period and total longevity of females decreased with increasing salinity, but this trend was not affected by diet type. Average offspring production in the groups fed with zeolite was in the range of 861-1160 offspring compared to unfed groups (604-741 offspring) (P<0.05). The encysted embryos percentage was different in the range of 20-35%. According to the results, the inclusion of 2% zeolite in salinity within 80-130 ppt were better for growth of the Artemia to maturity. Also, it is recommended to add zeolite in the Artemia diet with the increasing trend in salinity from 80 to 180 ppt for improving broodstock reproductive performance.

Volume 25, Issue 2 (2-2023)
Abstract

The genetic evaluation of dairy bulls is based on their daughters’ production, type traits, and fertility. It is unknown how the different number of days open of the daughters of a bull influences its Estimated Breeding Values (EBVs) and ranking in the population. The present study aimed to examine the effect of days open on milk production of Holstein dairy cows and the ranking of the bulls according to their predicted breeding values. A total number of 706,653 test day records of the first parity of 78,517 Iranian Holstein cows in 448 herds during 1991 to 2016 were used. The daughters of the same bulls were allocated into nine groups of days open, the differences of which were 21 days. Data were analyzed using a random regression model and predicted the breeding values of bulls. The effect of herd-year-season on milk yield were significant (P≤ 0.001). The heritability of 270 days milk for the first to ninth groups were estimated to be 0.24(±0.04), 0.26(±0.02), 0.23(±0.02), 0.21(±0.03), 0.18(±0.03), 0.19(±0.04), 0.16(±0.05), 0.17(±0.05) and 0.11(±0.04), respectively. The Spearman rank correlation coefficient of predicted breeding value of the same sires in different groups were 0.60-0.75 (P≤ 0.01). The results showed a negative relation between the number of days open and the predicted breeding value of bulls. It can be concluded that the number of days open affects the prediction of breeding value and ranking of the sires and it should be corrected for, while predicting the breeding value of sires.
 

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