Assessing resilience of dairy cattle by studying impact of heat stress on predicted feed intake

M.L. Vanrobays, Hedi Hammami, Aurelie laine, Hélène Soyeurt, J. Vandenplas, E. Froidmont, Nicolas Gengler

Research output: Chapter in Book/Report/Conference proceedingAbstract

Abstract

Milk production and feed intake of dairy cows are both affected by heat stress (HS) which is also a potentially important cause of discomfort for animals. Therefore, strategies allowing mitigation of HS effects are required. Genetic selection appears to be a good solution because this tool permits to improve cumulatively and continuously traits of interest. In this context, the goal of this study was to estimate genetic variation of milk yield and predicted feed intake over the whole trajectory of temperature humidity index (THI) using a reaction norm approach. A total of 30,161 fat and protein corrected milk (FPCM) yield records from 4,577 Holstein cows were used. These data were collected between June 2009 and December 2010 in 453 herds in the Walloon Region of Belgium. Daily dry matter intake (DMI; g/d) of dairy cows were estimated at the day of FPCM records from the prediction equation of NRC (2001), which is based on predicted body weight, FPCM, and week of lactation. Body weight of cows was estimated using a two-step approach allowing to predict body weight throughout the lactation from body weight calculated using linear conformation traits. Daily values of THI were computed from meteorological data using the mean of daily values of dry bulb temperature and relative humidity. Bivariate random regression test-day models with random linear regressions on THI values were developed for FPCM and DMI. Estimated average daily heritability for FCPM was 0.08 and decreased slightly at extreme THI values (from 0.10 (THI = 17) to 0.06 (THI =75)). Heritabilities of DMI also decreased with increasing THI values: from 0.11 (THI=17) to 0.05 (THI=75). Genetic correlations between FPCM and DMI were positive and ranged from 0.85 (THI=17) to 0.55 (THI=75). This decrease could be explained by the decrease of DMI under HS which could be balanced by the buffering effect of body tissue mobilization. Combining these novel results with known effects of HS on body fat mobilization might help to disentangle complex relationships between mobilization and intake under HS; this being also an important issue in assessing well-being of dairy cattle and their resilience potential to HS.
Original languageEnglish
Title of host publicationFeeding behaviour as an indicator of health and welfare
Subtitle of host publicationProceedings of the third dairycare conference 2015, Zadar, Croatia, October 5th and 6th 2015
EditorsC.H. Knight
PublisherDairyCare COST Action FA1308
Pages49-49
ISBN (Print)9780993017629
Publication statusPublished - 2015
EventProceedings of the Third Dairycare Conference 2015 - Zadar, Croatia
Duration: 5 Oct 20156 Oct 2015

Conference

ConferenceProceedings of the Third Dairycare Conference 2015
CountryCroatia
CityZadar
Period5/10/156/10/15

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