Effects of induced subacute ruminal acidosis on milk fat content and milk fatty acid profile

Abstract

Two lactating dairy cows fitted with a rumen cannula received successively diets containing 0%, 20%, 34% and again 0% of wheat on a dry matter basis. After 5, 10 and 11 days, ruminal pH was measured between 8:00 and 16:00 hours, and milk was analysed for fat content and fatty acid profile. Diets with 20% and 34% wheat induced a marginal and a severe subacute ruminal acidosis respectively. After 11 days, diets with wheat strongly reduced the milk yield and milk fat content, increased the proportions of C8:0 to C13:0 even- or odd-chain fatty acids, C18:2 n-6 and C18:3 n-3 fatty acids but decreased the proportions of C18:0 and cis-9 C18:1 fatty acids. Wheat also increased the proportions of trans-5 to trans-10 C18:1, the latter exhibiting a 10-fold increase with 34% of wheat compared with value during the initial 0% wheat period. There was also an increase of trans-10, cis-12 C18:2 fatty acid and a decrease of trans-11 to trans-16 C18:1 fatty acids. The evolution during adaptation or after return to a 0% wheat diet was rapid for pH but much slower for the fatty acid profile. The mean ruminal pH was closely related to milk fat content, the proportion of odd-chain fatty acids (linear relationship) and the ratio of trans-10 C18:1/trans-11 C18:1 (nonlinear relationship). Such changes in fatty acid profile suggested a possible use for non-invasive diagnosis of subacute ruminal acidosis.

Epidemiological and Diagnostic Studies on Subacute Ruminal Acidosis in Dairy Cows

“…The fat % of the total milk in the bulk tank was within normal range (tab.4). These results agree with those reported by Kleen et al (2003);; Enjalbert et al (2008) and Bipin et al (2016) but not agree with Oetzel, (2005);Tajik et al (2009) who reported that SARA had no effect on milk fat % in farm condition.…”

Effect of induction of subacute ruminal acidosis on milk fat profile and rumen parameters

“…Milk odd-and branched-chain FA (OBCFA) are of particular interest in this respect because they have been linked to the rumen fermentation pattern (Vlaeminck et al, 2006b;Cabrita et al, 2007;Craninx et al, 2008). Moreover, accumulation of FA during rumen biohydrogenation depends on the rumen environment, with predominant switches toward the C18:1 trans-10 pathway at low ruminal pH (e.g., Enjalbert et al, 2008). Because of these relationships and the ease of obtaining milk samples, monitoring the FA profile of milk has potential value in the diagnosis of SARA and could facilitate its prevention.…”

Finishing strategies for steers based on pasture or silage plus grain and time on feed and their effects on beef quality

“…However, the proportion used could have affected the ruminal pH, which then affected the IMF fatty acid profile. Enjalbert et al (2008) reported lower contents of C18:0 and CLA c-9 t-11 in milk fat when wheat grain was added to the diet to induce SARA. Colman et al (2010) also found that the concentrations of C18:0 and CLA c-9 t-11 in milk fat were lower in the third week postinduction of mild SARA with wheat grain in the diet.…”

“…However, the pH of the rumen is primarily influenced by the fermentable carbohydrate in the diet, and the amount and source of starch and/or the rate of ruminal degradation of starch affects biohydrogenation in the rumen (Mohammed et al, 2010). Wheat grain reduces the ruminal pH and is used to induce subacute ruminal acidosis (SARA); subacute ruminal acidosis results in changes of the fermentation pattern in the rumen, with possible changes in the production of fatty acids (Enjalbert et al, 2008). These authors reported that diets with 20 and 34% wheat induced a marginal or a severe SARA, respectively.…”