Abstract

The results of experiments with Friesian cows with breeding indices of 126 (HBI) or 102 (LBI) are presented. HBI cows produced an average of 153 kg milkfat/cow in the 1979 to 1981 lactations and LBI cows produced 125 kg milkfat/cow. HBI cows lost 0.7 of a condition score during lactation whereas LBI cows maintained their condition score. In 2 of the 4 staff feeding experiments the dry matter intake of pasture/kg 0.75 was significantly higher for HBI cows than LBI cows. There were no differences between the 2 groups of cows in their ability to metabolise dietary energy, nor in their heat production. JBI cows partitioned a greater proportion of their dietary energy to milk energy than LBI cows. Blood samples taken hourly for 24 h periods from cows fed indoors were analysed for growth hormone, insulin, glucose,

ED, Fielden, and K Moller

Proceedings of the New Zealand Society of Animal Production, Volume 43, , 59-62, 1983