A comparison of four patterns of allocating maize during lactation to Friesian cows grazing tropical pastures

Abstract

Milk yields were compared over a 280-day lactation using four patterns of allocation of a fixed amount of grain. Four groups of four Friesian cows grazed a mixed tropical grass (Panicum maximum) and legume (Neonotonia wightii cv. Tinaroo) pasture at 1.1 cows/ha from January to December 1980. The lactation was split into four feeding periods: days 1 - 10,11- 100,10 1 - 190, 191-280. All cows were fed a total of 610 kg hammermilled maize, with 10 kg grain fed during the initial covariate period. The four feeding patterns were: (i) flat rate (FR), where cows received 2.22 kg grain/day; (ii) all early (AE), where cows received 600 kg grain between days 11 and 100; (iii) high early, low late (HELL), where cows were fed 3.5, 2.17 and 1.0 kg/day for periods 11-100,101-190and 191- 280 days of lactation; and (iv) low early, high late (LEHL), where cows were fed in the reverse pattern to HELL. Milk yields per cow over 280 days were 4145, 3942, 3794 and 3630 kg [l.s.d. (P=0.05)= 436 kg] for HELL, FR, LEHL and AE respectively. There was very poor utilization of grain by cows fed AE. The relation between milk yield and grain intake in days 1 1-100 of lactation was described by the equation: Y= 13.9+ 1.77X-0.18X2 (P<0.01, s.e.b1= 0.48, s.e.b2 = 0.06), where Y = milk yield (kg/cow.day) and X = grain intake (kg/cow.day). Apportioning more grain to late lactation, when pasture on offer was low, did not compensate for the loss of milk production in early lactation by cows fed LEHL. Cows fed LEHL lost more liveweight in early lactation than all other treatments, but regained this weight in late lactation. Cows in all treatments had similar liveweights (mean 518 kg) at 280 days. Milk butterfat and solids-not-fat yields over 280 days were not significantly different (P>0.05) for any of the four treatments.