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dc.contributor.authorBanos Gen_US
dc.contributor.authorCoffey MPen_US
dc.date.accessioned2013-09-11T15:06:49Z
dc.date.available2013-09-11T15:06:49Z
dc.date.issued2010en_US
dc.identifier.citation4:2
dc.identifier.other12705en_US
dc.identifier.urihttp://hdl.handle.net/11262/7933
dc.identifier.urihttp://dx.doi.org/doi:10.1017/S1751731109991182en_US
dc.description.abstractThe objective of this study was to quantify the genetic association of body energy assessed throughout lactation with a cow’s fertility. Nine direct and indirect body energy traits were defined at different stages of lactation. Four were daily records of energy balance, energy content, cumulative effective energy (CEE) and body condition score (BCS) calculated between lactation days 4 and 311. The other five traits included duration of negative energy balance (DNEB), rate of recovery during DNEB (RNEB), sum of negative energy balance (SNEB), nadir of energy content (NEC) and number of days from calving to NEC. Of these traits, energy balance, DNEB, RNEB and SNEB were primarily based on individual cow feed intake and milk yield, and considered direct measures of body energy. The other traits were calculated from body lipid and protein changes, predicted from BCS and live weight profiles, and were considered indirect measures of body energy. Fertility was defined by number of days between calving and commencement of luteal activity (DLA), first observed oestrus (DH) and conception (DC), and number of services per conception. A total of 957 cows in their first four lactations were considered in the study. Genetic models fitted cubic splines to define longitudinal traits (energy balance, energy content, CEE and BCS) and calculate heritability and genetic correlation with fertility. Daily heritability estimate ranges were 0.10 to 0.34, 0.35 to 0.61, 0.32 to 0.53 and 0.24 to 0.56 for energy balance, energy content, CEE and BCS, respectively, and, in most cases, tended to increase towards the middle of lactation and remain relatively stable thereafter. Of the other body energy traits, heritability of NEC (0.44) was the most notable. Statistically significant (P < 0.05) genetic correlations of DH with daily energy balance, energy content, CEE and BCS ranged from −0.16 to −0.28, −0.35 to −0.48, −0.16 to −0.26 and −0.37 to −0.44, respectively. For DC, respective estimates were −0.28 to −0.64, −0.37 to −0.60, −0.30 to −0.48 and −0.29 to −0.53. For DLA, they ranged from −0.47 to −0.56 with energy content and from −0.50 to −0.74 with BCS. Of special interest was the genetic correlation of NEC with DH (−0.54) and DC (−0.48). Results suggest that indirect measures of body energy have the strongest genetic association with cow fertility. NEC and early lactation (circa day 50) BCS and energy content are the most useful traits for selection in terms of the correlated improvement in a cow’s capacity to resume her reproductive activity post partum.en_US
dc.relation.isformatof12705.pdfen_US
dc.relation.ispartofAnimalen_US
dc.rightsCopyright © The Animal Consortium 2009
dc.subjectBody energyen
dc.subjectDairy cattleen
dc.subjectFertilityen
dc.titleGenetic association between body energy measured throughout lactation and fertility in dairy cattleen_US
dc.description.versionVersion of record
dc.extent.pageNumbers189en_US
dc.extent.pageNumbers199en_US


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