The Effect of Risk for Subacute Ruminal Acidosis, Feeding Frequency, and Photoperiod on the Feeding Behaviour of Lactating Dairy Cows

Abstract

Cows fed the same high-grain diet have a large variation in rumen pH and can be categorized as higher or lower risk for developing subacute ruminal acidosis (SARA). The objective of this research was to determine if differences in feeding behaviour existed between the two categories and if these differences could be managed with feeding frequency or photoperiod. In the preliminary studies, the feeding behaviour of 6 higher risk cows and 10 lower risk cows was observed over 24 hours. Cows at a higher risk for SARA ate for a longer period of time (186 vs. 153 min; P = 0.01) soon after feed was delivered once per day in the morning and less time overnight (19 vs. 43 min; P = 0.01) before feed delivery the next day than lower risk cows. In the primary experiment of Experiment 1, 4 higher risk and 4 lower risk cows were fed either once or three times daily and feeding behaviour was observed. Cows that were fed 3 times vs. once daily reduced eating time in the morning (103 vs. 145 min; P < 0.01) and increased eating time overnight (76 vs. 44 min; P < 0.01) which resulted in a decrease in the severity of SARA in higher risk cows (area below a pH of 5.8; 51 vs. 98 pH × min/d; P = 0.05) when they were fed 3 times vs. once daily. In Experiment 2, 30 cows were subjected to a long day or short day photoperiod and behaviour was observed. A long day photoperiod tended to increase eating time between 0300 to 0800 h (53 vs. 39 min; P = 0.06) and reduced overall daily sorting (P = 0.07). These findings suggest that feeding behaviour is a contributing factor to increased risk for SARA, where eating for longer following feed delivery increases the risk. Feeding more often and providing more hours of light increased the daily distribution of eating time, which may reduce the risk for SARA.