Comparison of the nutritional regulation of milk fat secretion and composition in cows and goats

Abstract

A study with 2 ruminant species (goats and cows) with inherent differences in lipid metabolism was performed to test the hypothesis that milk fat depression (MFD) due to marine lipid supplements or diets containing high amounts of starch and plant oil is caused by different mechanisms and that each ruminant species responds differently. Cows and goats were allocated to 1 of 3 groups (4 cows and 5 goats per group) and fed diets containing no additional oil (control) or supplemented with fish oil (FO) or sunflower oil and wheat starch (SOS) according to a 3 × 3 Latin square design with 26-d experimental periods. In cows, milk fat content was lowered by FO and SOS (-31%), whereas only FO decreased milk fat content in goats (-21%) compared with the control. Furthermore, FO and SOS decreased milk fat yield in cows, but not in goats. In both species, FO and SOS decreased the secretion of <C16 and C16 fatty acids (FA), and FO lowered >C16 FA output. However, SOS increased milk secretion of >C16 FA in goats. Compared with the control, SOS resulted in similar increases in milk trans-10,cis-12 conjugated linoleic acid (CLA) in both species, but caused a 2-fold larger increase in trans-10 18:1 concentration in cows than for goats. Relative to the control, responses to FO in both species were characterized by a marked decrease in milk concentration of 18:0 (-74%) and cis-9 18:1 (-62%), together with a ~5-fold increase in total trans 18:1, but the proportionate changes in trans-10 18:1 were lower for goats. Direct comparison of animal performance and milk FA responses to FO and SOS treatments demonstrated interspecies differences in mammary lipogenesis, suggesting a lower sensitivity to the inhibitory effects of trans-10,cis-12 CLA in goats and that ruminal biohydrogenation pathways are more stable and less prone to diet-induced shifts toward the formation of trans-10-containing intermediates in goats compared with cows. Even though a direct cause and effect could not be established, results suggest that regulation of milk fat synthesis during FO-induced MFD may be related to a shortage of 18:0 for endogenous mammary cis-9 18:1 synthesis, increase in the incorporation of trans FA in milk triacylglycerols, and limitations in the synthesis of FA de novo to maintain milk fat melting point. However, the possible contribution of biohydrogenation intermediates with putative antilipogenic effects in the mammary gland, including trans-9,cis-11 CLA, trans-10 18:1, or cis-11 18:1 to FO-induced MFD cannot be excluded.

Comparison of mammary lipid metabolism in dairy cows and goats fed diets supplemented with starch, plant oil, or fish oil

“…Faced with the absence of direct interspecies comparisons of diet-induced MFD among these species, a comparative study with lactating cows and goats was undertaken to determine the mechanisms underlying the differences of mammary lipogenic responses between these ruminant species. From this study, animal performance responses including milk fat yield, FA composition (Toral et al, 2015), and rumen metabolism (Toral et al, 2016) were reported and revealed relevant interspecies differences and species-by-diet interactions. The present study aimed to provide further insight into the mechanisms regulating mammary lipogenesis in ruminants.…”

“…The details of the experimental design have been described in Toral et al (2015). Briefly, 12 multiparous nonpregnant Holstein cows and 15 multiparous nonpregnant Alpine goats were allocated to 1 of 3 groups (4 cows and 5 goats each) and used in a replicated 3 × 3 Latin square to test the effects of 3 treatments during three 25-d experimental periods.…”

“…All animals were offered grass hay ad libitum supplemented with concentrates (control, FO, or SOS). Formulation of experimental concentrates and chemical composition of concentrates and grassland hay were described in Toral et al (2015). Briefly, the control concentrate was based on (% DM) cracked corn grain (54.9), pelleted dehydrated alfalfa (29.4), soybean meal (14.3) and a mineral-vitamin premix (1.4).…”

“…An indirect comparison of cow and goat performance and milk FA responses to diets known to induce MFD in the bovine reveals relevant species-by-diet interactions, with goats being less sensitive to diet-induced MFD (Shingfield et al, 2010;Toral et al, 2014) even though recent studies have demonstrated their susceptibility when fed marine lipids at a relatively high dose (2.2% DM; Toral et al, 2015). The reasons for the differential lipogenic responses between these ruminant species are not well understood, but based on indirect comparisons of milk FA composition, differences in ruminal BH and mammary lipid metabolism (Chilliard et al, 2007Shingfield et al, 2010) could be implicated.…”

Effect of Addition of Whey Proteins on the Microstructure and Syneresis of “Suero Costeño”Made from Goat Milk

“…Cow cattle are the most significant milk producer in the world, but in recent years there has been a considerable increase in the production and industrialisation of goat milk [1], and there is a growing interest in research and investment in goat milk in several countries, mainly due to its attractive nutrient content. Regarding that, goat milk has lower lactose content and a higher concentration of total solids (mostly proteins and fats) and nutrients than cow milk [3]- [6]. Fat from goat milk influences positively on sensory properties of food products, more than that from cow milk [5].…”