Short communication: Genetic parameters of individual fatty acids in milk of Canadian Holsteins

Abstract

The objective of the present study was to estimate heritabilities of milk fatty acids (FA) and genetic and phenotypic correlations among milk FA and milk production traits in Canadian Holsteins. One morning milk sample was collected from each of 3,185 dairy cows between February and June 2010 from 52 commercial herds enrolled in Valacta (Ste-Anne-de-Bellevue, Quebec, Canada). Individual FA percentages (g/100 g of total FA) were determined for each sample by gas chromatography. After editing the data, 2,573 cows from 46 herds remained. Genetic parameters were estimated using multitrait animal models fitted under REML. The model included fixed effects of age at calving and stage of lactation each nested within parity and random effects of herd-year-season of calving, animal, and residual. The pedigree of animals with data was traced back 5 generations on both the male and female sides to account for relationships among animals. The estimates of heritability for individual FA ranged from 0.01 to 0.39, with standard errors ranging from 0.01 to 0.06. Generally, monounsaturated FA (MUFA) and saturated FA (SFA) showed higher heritability estimates than polyunsaturated FA (PUFA). Overall, SFA were negatively genetically correlated with MUFA and PUFA, whereas genetic correlations between MUFA and PUFA were positive. The SFA showed positive associations with fat yield and fat percentage, whereas unsaturated FA were negatively associated with fat yield and fat percentage. Bovine milk FA composition could be improved through genetic selection, and selection for MUFA or against SFA could alter the bovine milk fat profile in a desirable direction.

Genetic and environmental relationships of detailed milk fatty acids profile determined by gas chromatography in Brown Swiss cows

“…In previous studies where the individual fatty acids were quantified with GC, the results were commonly expressed as a ratio between the weight of a given fatty acids and the weight of the total fatty acids or milk fat. The heritability estimates reported in these GC-based studies (Bobe et al, 2008;Garnsworthy et al, 2010;Bilal et al, 2014) are comparable to those found in the current paper or somewhat higher (Stoop et al, 2008;Schennink et al, 2008). In contrast, the results from studies based on FTIR predictions (Soyeurt et al, 2007;Bastin et al, 2011Bastin et al, , 2013 have commonly been expressed in terms of the weight of a single fatty acid or group of fatty acids per unit of milk (kg or L) due to the low accuracy of FTIR-based predictions of milk fat content (Ferragina et al, 2015).…”

“…Few studies have used GC to examine how genetic and herd factors affect the milk profile of 23 to 26 fatty acid traits: namely Stoop et al (2008), Garnsworthy et al (2010), and Heck et al (2012). Only Bilal et al (2014) reported data on 33 fatty acids and also evaluated all the genetic parameters based on GC analysis for the Holstein Friesian breed. In Brown Swiss cows, the genetic parameters of only 4 fatty acid categories (i.e., SFA, unsaturated fatty acids, MUFA, and PUFA predicted by FTIR and expressed as the relative content in a kilogram of milk) were previously estimated (Tullo et al, 2014).…”

Genetic analysis of groups of mid-infrared predicted fatty acids in milk

“…This may be due to different number of test-day records, model, and units used in the studies. Bilal et al (2014) reported a wide range (−0.01 to 0.83) of phenotypic correlations for individual fatty acids expressed as a proportion of total fatty acids, which were measured using the GC method. Soyeurt et al (2008a) observed phenotypic correlations over the lactation between saturated and monounsaturated fatty acid groups in milk and found genetic correlations were lower in initial lactation and increased during mid and late lactation.…”

Genome-wide association study of milk fatty acid composition in Italian Simmental and Italian Holstein cows using single nucleotide polymorphism arrays

“…In dairy cows, typical milk fat content is about 70% SFA, 25% MUFA, and 5% PUFA, which departs considerably from the ideal fatty acid profile for human health (8% SFA, 82% MUFA, and 10% PUFA; Bilal et al, 2014). To improve the healthiness of human diets…”

“…In fact, these differences in heritability between longchain FA metabolism versus short/medium-chain FA metabolism create the opportunity to modify milk FA composition by selective animal breeding. If realized, such improved breeds would represent a more permanent and reliable solution than changes in livestock production systems, offering at the same time more product choices to consumers (Mele et al, 2007;Schennink et al, 2009b;Bilal et al, 2014).…”