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Author

Mohamad A Kossaibati

Bio: Mohamad A Kossaibati is an academic researcher from University of Reading. The author has contributed to research in topics: Heritability & Dairy cattle. The author has an hindex of 1, co-authored 1 publications receiving 161 citations.

Papers
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Journal ArticleDOI
TL;DR: Two-trait analysis of fertility and milk yield was investigated as a method to estimate fertility breeding values when culling or selection based on milk yield in early lactation determines presence or absence of fertility observations in later lactations.

167 citations


Cited by
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Journal ArticleDOI
TL;DR: Broadening of breeding goals through recent changes to selection indices decreased the similarities of top bull listings across the various countries, with a slightly greater commonality among sires of top bulls.

595 citations

Journal ArticleDOI
TL;DR: Genetic correlations among traits indicated that different traits measured different aspects of reproductive performance of a dairy cow could be used jointly in a fertility index to allow for selection for better fertility of dairy cattle.

264 citations

Journal ArticleDOI
TL;DR: Estimates of genetic relationships between lactation persistency and reproductive performance in first lactation and relationships with day in milk at peak milk yield and estimated 305-d milk yield found heifers younger than average when first inseminated and/or conceived successfully at first inSEmination tended to have a more persistentFirst lactation.

143 citations

Journal ArticleDOI
TL;DR: Increased risk of culling was observed for cows that required hard pull, calved small calves, or dead calves, and cows that require more services per conception were at greater risk of being culled.

126 citations

Journal ArticleDOI
TL;DR: This paper reviews methods of measuring reproductive performance and the association of the level of milk production with pregnancy rate at the herd and individual levels, and it is not clear if there is any association between higher milk yield and the probability and timing of pregnancy.
Abstract: There is much debate about possible antagonism between high milk production and reproductive performance. This paper reviews methods of measuring reproductive performance and the association of the level of milk production with pregnancy rate at the herd and individual levels. The main question is whether fertility (the capacity for reproductive function and successful pregnancy) of dairy cows has in fact declined, as opposed to the success of management systems and people at meeting the metabolic, nutritional, housing, and social needs of increasingly productive animals but with no less inherent capacity to achieve and maintain pregnancy; and if fertility really has diminished, the extent to which this decline is caused by increased milk production. There is no doubt that production per cow has increased, but it is unclear how much of this increase can explain the apparent decrease in fertility. It is important to separate the biology of reproductive function from the effects of economically based management decisions about culling and continuation of breeding. Most traditionally-used measures of reproductive performance (calving interval, conception rate, non-return rate) are incomplete or severely biased outcome measures. Both herd and cow-level data should include as much information as possible on confounders of the relationship of production with reproduction. Population or herd-level data should not be used to make inferences about individual-level associations. Considering the quality of data and analytic methods in the published literature, it is not clear if there is any association between higher milk yield and the probability and timing of pregnancy, either among cows at various levels of production in a population at one time, or with increasing production over time.

126 citations