The effect of kale cultivar and sowing date on dry-matter intake, crop utilization, liveweight gain and body condition score gain of pregnant, nonlactating dry dairy cows in winter in New Zealand

Abstract

An outdoor grazing study on kale was conducted with pregnant, nonlactating (dry) dairy cows over a 42-day winter grazing period commencing 9 June 2008. Kale treatments consisted of two kale cultivars varying in leaf:stem proportion ("Regal," a leafy variety and "Caledonian," a stemmy variety) and two sowing dates (8 November and 15 December). Measurements were made for dry-matter (DM) utilization, apparent DM intake, liveweight gain and changes in body condition score (BCS) for a total of 120 cows allocated to three replicate groups of the four factorial treatments. Cows were offered a daily allowance of 10 kg DM/cow of kale and 2.2 kg DM/cow of straw. Pregrazing DM yield was higher for kale sown in November (16,517 kg DM/ha) than December (13,867 kg DM/ha), but was unaffected by cultivar (average 15,192 kg DM/ha). "Regal" kale had a higher percentage of leaf compared with "Caledonian" (33.6% vs. 25.6%), lower content of NDF (32.4% vs. 34.1%), but similar metabolizable energy content (12.1 MJ/kg DM for both) in the whole plant. Despite the differences in pregrazing DM yield and forage quality among treatments, no differences were found in DM utilization (between 88.5% and 90.2%), apparent DM intake (between 9.4 and 9.6 kg DM/cow.day), liveweight gain (between 0.53 and 0.67 kg/cow.day) and BCS gain (between 0.43 and 0.46 unit/cow over 42 days). Manipulation of kale yield and quality through choice of cultivar and sowing date had no effect on the performance of pregnant, nonlactating dairy cows.