EATING PATTERNS OF LACTATING DAIRY-COWS OF 3 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 stu dy. 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, respe ctively. In cows of all three breeds, 89% of the grass meals (=94% of the total grass intake) occurred during the light phase (0400-2200) an d peaks of grass intake with large meals were always observed shortly after refilling the troughs. A similar diurnal distribution was eviden t for concentrate intake, but was less pronounced (28% eaten during th e dark phase), and peaks of concentrate intake occurred also in the ev ening and after midnight. Hay intake was negligible and was not consid ered 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 small er for JER cows than for HF and SI cows. Significant correlations betw een the size of grass meals and the duration of either the interval pr eceding or following that same meal were observed only for some animal s (in particular JER and SI cows) during the main eating period in the morning (0800-1300), but barely in the afternoon (1300-1700). Thus, t he short-term physiological control of meal-taking in dairy cows kept under normal farming conditions seems to be markedly influenced by ext ernal factors. Nevertheless, the data reveal differences in eating pat terns of lactating HF, SI, and JER cows. Whether or not the observed d ifferences in eating patterns have physiological consequences remains an interesting question for future investigations.