Effects of different model diets on milk composition and expression of genes related to fatty acid synthesis in the mammary gland of lactating dairy goats

Abstract

This study examined the effects of different roughage diets on milk composition and the expression of key genes associated with fatty acid (FA) synthesis in the mammary gland of lactating dairy goats. Eight multiparous lactating goats (body weight=43.6±2.5kg, 90±12 d in milk) fitted with external pudic artery and subcutaneous abdominal vein catheters were assigned to 2 treatments in a crossover design. The goats were fed different roughage diets with a similar concentrate-to-roughage ratio. The diets were (1) a high-quality roughage treatment (HQR) containing 28.5% Chinese wildrye hay, 19% corn silage, 9.5% alfalfa, and 43% concentrate or (2) a low-quality roughage treatment (LQR) containing 28% Chinese wildrye hay, 28% corn stover, and 44% concentrate, on a dry matter basis. Each feeding period lasted 21 d. The first 18 d served as an adaptation period, and the last 3 d served as a sample collection period. Dry matter intake, milk yield, and milk composition were measured. Milk and blood samples were collected for FA analysis. Mammary gland biopsies were performed after milking on the last day of each period and the tissues were analyzed for the mRNA expression of acetyl-coenzyme A carboxylase-α (ACACA), FA synthase (FASN), stearoyl CoA desaturase (SCD), and lipoprotein lipase (LPL). Dry matter intake and milk yield were not affected by the treatments. Milk fat (3.16 vs. 2.96%) and protein (2.99 vs. 2.89%) contents were higher in HQR goats than in LQR goats, and milk fat yield tended to be higher in HQR goats (16.7 vs. 15.1g/d). Milk FA composition was not different between treatments, except for C18:3n-3 (0.27 vs. 0.15g/100g). Compared with LQR goats, HQR goats had a higher vein concentration of total FA (0.62 vs. 0.44mg/mL). In HQR goats, the mammary balance of total FA increased (9.17 vs. 5.51g/d), whereas the clearance rate of total FA decreased (103.03 vs. 138.25 L/d). No differences were found in mammary blood flow, artery concentration, and mammary uptake of FA between treatments. Compared with LQR, the expression of FASN and ACACA tended to be increased by 20 and 18%, and the expression of LPL and SCD were increased by 39 and 50% in HQR, respectively. The results demonstrated that diets with HQR can increase milk fat content and yield as well as the expression of LPL and SCD in the mammary gland of dairy goats.

Puberty is a critical window for the impact of diet on mammary gland development in the rabbit

“…53 In an underfed sheep model, a reduction in Scd transcripts was observed, while no modifications to Scd expression were seen in the adverse overfed model. 54 However, although feeding over 3 weeks was sufficient to increase the expression of Scd transcripts in the mammary gland of dairy goats fed a quality modified diet, 15 an unbalanced diet during the peri-pubertal period did not modify mammary lipid metabolism during early pregnancy in our model.…”

“…Maternal diet‐induced obesity during both pregnancy and lactation negatively affected mammary gland function . Moreover, results showed that maternal exposure to protein restriction could change fatty acid metabolism in the mammary gland and thus modify milk composition . For these reasons, the neonatal period is also considered as critical through the consumption of maternal milk, the composition of which may vary depending on the dam's diet and thus have long‐term effects on offspring health.…”

“…14 Moreover, results showed that maternal exposure to protein restriction could change fatty acid metabolism in the mammary gland and thus modify milk composition. 15 For these reasons, the neonatal period is also considered as critical through the consumption of maternal milk, the composition of which may vary depending on the dam's diet and thus have longterm effects on offspring health. In a rabbit model, the ingestion of milk produced by dams fed an OD led to an increased adiposity in adulthood, as well as to impaired mammary function.…”

Effects of exogenous C18 unsaturated fatty acids on milk lipid synthesis in bovine mammary epithelial cells

“…Intracellular FAs were extracted according to a previously described procedure (Zhang et al ., 2015) with modifications (online Supplementary Materials and Methods).…”

Effects of isonitrogenous and isocaloric total mixed ration composed of forages with different quality on milk fatty acid composition and gene expression of mammary lipogenic enzymes in mid‐lactating dairy cows

“…Diets with different qualities of forages had distinct effects on milk FA composition, relating the expression of lipid metabolism‐related genes to the milk FA composition may be a key issue to milk FA regulating mechanisms (Chilliard, Ferlay, & Mansbridge, ; Mach et al., ). A diet with Chinese wildrye and alfalfa hay as the main forages was shown to increase the milk yield, the contents of milk fat and protein, and the expression of mammary lipogenic enzymes compared with corn stover as the forage fed to ruminants (Zhang, Ao, Khas‐Erdene, Song, & Zhang, ). A diet with alfalfa hay as the main forage increased the milk yield and the milk protein content compared to corn stover as the main forage diet fed to cows (Zhu et al., ).…”