Ingestive behavior and dry matter intake of dairy cattle grazing Kikuyu grass (<i>Cenchrus clandestinus</i>) pastures

Abstract

The objective of this study was to evaluate the effect of animal characteristics, grazing management, and supplementation on ingestive behavior and dry matter intake (DMI) of Kikuyu grass in lactating cows. Four trials were conducted with multiparous Holstein dairy cows in non-limiting forage conditions using 9 cows in each trial, 1 cow per paddock. Individual DMI was estimated through forage mass difference (pre- and post-grazing mass), ingestive behavior, and using markers [chromium oxide and undegradable acid detergent fibre (uADF)]. DMI was also estimated using 3 nutritional models (CSIRO, NRC, and AFRC). Grazing time and bite mass were positively related to the cow body weight, while bite rate showed a negative relationship with forage mass. The grazing time on a pasture of 42 d regrowth was less than the time spent grazing on a pasture of 28 or 56 d regrowth. DMI estimated by forage mass difference showed a positive relation with forage mass, supplement intake, and liveweight. DMI estimated using markers showed a positive relation with milk production and liveweight and a negative relationship with forage height. Forage mass difference and ingestive behavior measurements provided good estimates (R²>0.8) of DMI associated with forage mass, liveweight, and supplement intake in cows grazing Kikuyu grass.