Effect of subacute ruminal acidosis on milk fat concentration, yield and fatty acid profile of dairy cows receiving soybean oil

Abstract

The objective of this study was to investigate the effect of ruminal infusion of soybean oil (SBO) with either a moderate- or high-forage diet on fat concentration, yield and composition in milk from dairy cows. Six rumen-fistulated Holstein dairy cows (639+/-51 kg body weight, 140+/-59 days in milk) were used in the study. Cows were randomly assigned to one of two dietary treatments, a high forage:concentrate (HFC, 74:26) or a moderate forage:concentrate (MFC, 56:44) total mixed ration. Cows were fed at 08.00 and 13.00 h and pulse-dosed ruminally at 13.00 h over a 10-min duration with 2% of diet dry matter of SBO. Ruminal pH was recorded continuously. Cows receiving the MFC treatment had lower daily mean ruminal pH and ruminal pH was below 6.0 for a longer duration compared with the HFC treatment (640 vs. 262 min/d, P<0.05). Cows receiving the MFC treatment had a greater reduction (diet by week interaction, P<0.05) in milk fat concentration and yield than cows receiving the HFC treatment (42 vs. 22% and 45 vs. 21%, respectively). Additionally, cows receiving the MFC diet had a greater reduction in milk fat concentration (g/100 g FA) of FA <C16 (14 vs. 8%), and a greater increase in concentration of FA >C16 (17 vs. 9%), trans-10 18:1 (159 vs. 21%) and trans-9, cis-11 conjugated linoleic acid (121 vs. 55%) (P<0.05) compared with cows receiving the HFC diet. This study demonstrated that cows fed the MFC diet had lower ruminal pH and showed a greater rate of milk fat depression when infused with SBO.

Changes in feed intake, nutrient digestion, plasma metabolites, and oxidative stress parameters in dairy cows with subacute ruminal acidosis and its regulation with pelleted beet pulp

“…The findings of this study concur with the results of others [4,26]; DMI was not different between the dietary treatments. Paradoxically, reduced DMI was seen as a clinical sign of SARA [27], and several researchers have shown that DMI decreased during induced SARA experiments [28,29].…”

The Effects of Subacute Ruminal Acidosis on Milk Fatty Acid Profile in Dairy Cattle

“…Therefore, they supported the theory that low rumen pH, resulting from feeding low fiber diets, results in the incomplete biohydrogenation of FA (Griinari et al, 1998). AlZahal et al (2010) also demonstrated that cows being fed moderate forage: Concentrate had a greater increase in trans-10 FA and trans-9, cis-11 conjugated linoleic acid than high forage: Concentrate. Additionally, the levels of the isomers were also related to the polyunsaturated FA levels (AlZahal et al, 2010).…”

“…AlZahal et al (2010) also demonstrated that cows being fed moderate forage: Concentrate had a greater increase in trans-10 FA and trans-9, cis-11 conjugated linoleic acid than high forage: Concentrate. Additionally, the levels of the isomers were also related to the polyunsaturated FA levels (AlZahal et al, 2010). Baumgard et al (2000) detected a relationship in milk fat depression and increases in trans-10 cis-12 and C18:1 trans-10.…”

Active dry Saccharomyces cerevisiae can alleviate the effect of subacute ruminal acidosis in lactating dairy cows

“…A research model using cannulated dairy cows has defined SARA as a decline in ruminal pH below 5.6 for approximately 300 min/d (AlZahal et al, 2007a). Symptoms of SARA are variable, but often include depressed intake, resulting in poor body condition and reduced production (Plaizier et al, 2008), and may predispose cows to milk fat depression (AlZahal et al, 2009(AlZahal et al, , 2010. Ruminant nutritionists have used a spectrum of feed additives to improve ruminal pH and maximize fiber degradation, namely by directly feeding active dry bacteria and yeast and yeast culture products.…”