Eating patterns of lactating dairy cows of three different breeds fed grass ad lib.

Eating behavior of lactating cows of three breeds (Holstein-Friesian = HF, Simmental = SI, and Jersey = JER) was compared in the present study. The cows were kept in a loose housing system and fed grass and hay ad lib along with concentrates. Within 11 days, 1396, 1504, and 1682 grass meals were recorded and analyzed for HF, SI, and JER cows, respectively. In cows of all three breeds, 89% of the grass meals (= 94% of the total grass intake) occurred during the light phase (0400-2200) and peaks of grass intake with large meals were always observed shortly after refilling the troughs. A similar diurnal distribution was evident for concentrate intake, but was less pronounced (28% eaten during the dark phase), and peaks of concentrate intake occurred also in the evening and after midnight. Hay intake was negligible and was not considered for meal pattern analysis. JER cows ate generally less than HF or SI cows, but spent more time eating. Grass meal frequency was higher, but grass meal size and mean eating rate within grass meals was smaller for JER cows than for HF and SI cows. Significant correlations between the size of grass meals and the duration of either the interval preceding or following that same meal were observed only for some animals (in particular JER and SI cows) during the main eating period in the morning (0800-1300), but barely in the afternoon (1300-1700). Thus, the short-term physiological control of meal-taking in dairy cows kept under normal farming conditions seems to be markedly influenced by external factors.(ABSTRACT TRUNCATED AT 250 WORDS)