Genetic parameters for conjugated linoleic acid, selected milk fatty acids, and milk fatty acid unsaturation of Italian Holstein-Friesian cows

Abstract

The objective of this study was to estimate genetic parameters for conjugated linoleic acid (CLA) and other selected milk fatty acid (FA) content and for unsaturation ratios in the Italian Holstein Friesian population. Furthermore, the relationship of milk FA with milk fat and protein content was considered. One morning milk sample was collected from 990 Italian Holstein Friesian cows randomly sampled from 54 half-sib families, located in 34 commercial herds in the North-eastern part of Italy. Each sample was analyzed for milk percentages of fat and protein, and for single FA percentages (computed as FA weight as a proportion of total fat weight). Heritabilities were moderate for unsaturated FA, ranging from 0.14 for C16:1 to 0.19 for C14:1. Less than 10% of heritability was estimated for each saturated FA content. Heritability for index of desaturation, monounsaturated FA and CLA/trans-11 18:1 ratio were 0.15, 0.14, and 0.15, respectively. Standard errors of the heritability values ranged from 0.02 to 0.06. Genetic correlations were high and negative between C16:0 and C18:0, as well as between C14:0 and C18:0. Genetic correlations of index of desaturation were high and negative with C14:0 and C16:0 (-0.70 and -0.72, respectively), and close to zero (0.03) with C18:0. The genetic correlation of C16:0 with fat percentage was positive (0.74), implying that selection for fat percentage should result in a correlated increase of C16:0, whereas trans-11 C18:1 and cis-9, trans-11 C18:2 contents decreased with increasing fat percentage (-0.69 and -0.55, respectively). Genetic correlations of fat percentage with 14:1/14 and 16:1/16 ratios were positive, whereas genetic correlations of fat percentage with 18:1/18 and CLA/trans-11 18:1 ratios were negative. These results suggest that it is possible to change the milk FA composition by genetic selection, which offers opportunities to meet consumer demands regarding health aspects of milk and dairy products.

Effectiveness of mid-infrared spectroscopy to predict fatty acid composition of Brown Swiss bovine milk

“…The FA composition of Brown Swiss milk was consistent with findings from Mele et al (2009) for Holstein Friesian cows reared in north Italy, but it was slightly lower than results reported by DePeters et al (1995) on Brown Swiss milk in a study aimed at comparing the variation of FA composition among three breeds fed and managed similarly in the United States. Regarding the saturation of milk fat, as reported in Table 2, SFA was the most important group of FA followed by MUFA and PUFA; this is in accordance with the literature that reported a normal presence of SFA, MUFA and PUFA of 70%, 25% and 5%, respectively (Grummer, 1991).…”

“…The iso-C14:0, C18:3n-3, t10-C18:1, iso-C16:0 and c11-C18:1 showed the largest CV (0.47,0.41,0.38,0.37 and 0.37,respectively). The CLA c9,t11-C18:2 showed lower CV than Mele et al (2009) and Stoop et al (2008).…”

“…Milk fat was extracted according to Mele et al (2009). Methyl esters of medium-and long-chain FA were prepared by the alkali-catalyzed trans-methylation procedure in Christie (1982) with C9:0 and C23:0 methyl esters (Sigma Chemical Co., St. Louis, MO) as the internal standards.…”

“…Several studies estimated genetic variation of FA (Soyeurt et al, 2007;Stoop et al, 2008;Mele et al, 2009) but gas chromatography (GC) is an expensive and time-consuming analysis; hence, a rapid method to determine FA in milk is crucial to extend the collection of phenotypic records at the population level.…”

Perfil tecnológico de cepas de bifidobactéria em cultura pura e em co-cultura com Streptococcus thermophilus em leites orgânico e convencional

“…Todos os produtos orgânicos (leite fresco e leites fermentados) apresentaram, em média, teores de CLA semelhantes, sem diferenças estatísticas significativas. Estes resultados confirmam dados previamente obtidos em pesquisas conduzidas com leites, iogurtes e leites fermentados (PRANDINI et al, 2007;COLLOMB et al, 2008;MELE et al, 2009;MOLKETIN, 2009 em leites orgânico e leite convencional. Médias (n = 4) com letras diferentes são significativamente diferentes (P ≤ 0,05).…”