Significant differences in fertility between dairy cows selected for one QTL located on bovine chromosome 3 are not attributable to energy balance, although eating behaviour is affected

Abstract

animal Significant differences in fertility between dairy cows selected for one QTL located on bovine chromosome 3 are not attributable to energy balance, although eating behaviour is affected S. Coyral-Castel 1,2,3,4,5 , P. Faverdin 6,7 , C. Ramé 1,2,3,4 , S. Fré ret 1,2,3,4 , D. Guillaume Improvement of reproduction in dairy cows has become a major challenge in dairy production. We have recently shown that dairy cows carrying the 'fertil2' haplotype for one quantitative trait locus (QTL), affecting female fertility and located on the bovine chromosome 3, had a significantly lower conception rate after the first artificial insemination than cows carrying the 'fertil1' haplotype. The objective of this paper was to study other phenotypic modifications linked to this QTL. In the present study, 23 'fertil1' and 18 'fertil2' cows were characterized for live weight, milk production, food intake, eating behaviour and plasma metabolites. These parameters were measured during the first lactation, from calving to 40 weeks postpartum (wkpp). In the first 7 weeks of lactation, 'fertil1' primiparous cows had a significantly higher live BW and milk production than 'fertil2' cows. Dry matter intake tended to be slightly higher for 'fertil1' than for 'fertil2' primiparous cows in this period. However, energy balance was similar for the two haplotypes in the whole lactation, except in the first wkpp, and consequently, could not explain their different fertility. The major observation concerned the eating behaviour. 'Fertil1' primiparous cows had a significantly lower eating rate than 'fertil2' cows during the 40 weeks of lactation. In parallel, 'fertil1' cows spent significantly more time at the feeder for a similar number of visits than 'fertil2' cows. Furthermore, no differences in plasma concentrations of non-esterified fatty acids and insulin were observed between the two haplotypes. Plasma glucose was significantly lower in 'fertil1' than in 'fertil2' cows in the second wkpp. Taken together, our results show that 'fertil1' and 'fertil2' dairy cows, with different fertility, have also different eating behaviour without any variation in energy balance, except in the first week of lactation.Keywords: dairy cow, eating rate, quantitative trait locus, metabolite ImplicationsThe fall in dairy cows' fertility is related, in part, to the strong genetic selection for milk production. It has been shown that several bovine Quantitative Trait Loci (QTL) affected female fertility. However, other physiological roles of these QTLs are not clearly established. As the effect of a high milk production is associated with the negative energy balance at the beginning of lactation (high needs for energy and limited postpartum feed intake), we studied several zootechnical and metabolic parameters in dairy cows carrying contrasting haplotypes at one female fertility QTL located on the BTA3, and presenting a phenotypic difference in fertility. These experiments are of particularly strong interest with the development of genomic selection.

Resistin in Dairy Cows: Plasma Concentrations during Early Lactation, Expression and Potential Role in Adipose Tissue

“…Primiparous cows were fed ad libitum with two total mixed rations according to their stage of lactation using the INRA French feeding system [16] as described in [16]. Dry matter intake was determined from the intake of fresh matter and the dry matter content of each feed of the ration.…”

“…Dry matter intake was determined from the intake of fresh matter and the dry matter content of each feed of the ration. The chemical composition of each feed is the same as described in [16]. The feeding values of the different feeds were calculated using chemical composition according the methods defined in INRA feeding systems [16].…”

“…The chemical composition of each feed is the same as described in [16]. The feeding values of the different feeds were calculated using chemical composition according the methods defined in INRA feeding systems [16]. Energy balance corresponds to the difference between energy needs for body maintenance, pregnancy and lactation, and energy intake.…”

Unraveling the Adipose Tissue Proteome of Transition Cows through Severe Negative Energy Balance

“…As LBW is affected by digestive contents, the estimation of empty body weight (EBW) was corrected for the digestive tract content. A change of 4.5 kg of digestive contents per kg of dry matter intake (DMI) was assumed [12]. Variation of EBW (VEBW) was calculated day after day: EBW of the previous day was taken as a reference weight [12].…”

“…A change of 4.5 kg of digestive contents per kg of dry matter intake (DMI) was assumed [12]. Variation of EBW (VEBW) was calculated day after day: EBW of the previous day was taken as a reference weight [12]. Live body weight and VEBW as compared to one month before calving were measured from 4 weeks before calving until 16 weeks after calving in females.…”