Determination of relationships between rumination and milk fat concentration and fatty acid profile using data from commercial rumination sensing systems

摘要

Milk fat production is highly influenced by nutritionand rumen fermentation. Rumination is an essentialpart of the ruminant digestive process and can serveas an indicator of rumen fermentation. The objectiveof this research was to quantify variation in ruminationtime between and within dairy herds and test forrelationships between rumination time and milk fatproduction and fatty acid (FA) profile as a proxy of rumenfermentation. Our hypothesis was that ruminationmay indicate disruptions to rumen fermentation andthat cows that spent less time ruminating would havelower milk fat due to these rumen disruptions. Datawere collected from 1,733 Holstein cows on 5 commercialdairy farms (4 in Pennsylvania and 1 in New York)of 200 to 700 head using 1 of 2 commercially-availablerumination sensing systems, CowManager SensOor eartags (Agis Automatisering BV) or SCR model HR-LDnneck collars (SCR Engineers). Rumination data werecollected for 7 consecutive days leading up to a DHIAtest, summed within day, then averaged to obtain meandaily minutes of rumination time. Milk samples fromthe DHIA test were analyzed for fat content by midinfraredspectroscopy and for milk FA profile by gaschromatography. Rumination data were analyzed usingmultiple linear regression models. Rumination time wasrelated to concentration of specific odd- and branchedchainand trans FA in milk but was not directly relatedto milk fat concentration. Rumination time also did notcontribute to models predicting milk fat concentrationafter accounting for other cow-level variables. Therewas a linear relationship between trans-10 C18:1 andrumination time that was positive after accounting forthe effect of farm (partial R~2 of 2.97% across all data,4.24% in SCR data, and 2.22% in CowManager data).Although rumination time was not related directly tomilk fat, it was associated with differences in trans andodd- and branched-chain FA that have been demonstratedto change during subacute ruminal acidosis orbiohydrogenation-induced milk fat depression, whichmay affect milk fat and other production variables.These associations suggest that further investigationinto using rumination data from commercial systemsto predict or identify the presence of these conditionsis warranted.