Resumen

MEESKE, R.; ROTHAUGE, A.; VAN DER MERWE, G.D.  y  GREYLING, J.F.. The effect of concentrate supplementation on the productivity of grazing Jersey cows on a pasture based system. S. Afr. j. anim. sci. [online]. 2006, vol.36, n.2, pp.105-110. ISSN 2221-4062.

The effect of concentrate feeding on milk production, milk composition, live weight, condition score and intercalving period of 60 Jersey cows grazing high quality pastures over two lactations was determined. Cows were fed at a no (NC), low (LC), medium (MC) or high (HC) level of concentrate. All cows received a mineral supplement of 300 g/day. The LC, MC and HC groups were fed an energy concentrate at 3, 6 and 9 kg/day, respectively from day 1 to day 150 of lactation followed by 1.5, 3 and 4.5 kg of energy concentrate per day from day 151 to day 300 of lactation. The energy concentrate consisted of 10.6% whole cottonseed, 42.1% rolled maize, 42.1% rolled wheat, 4.2% molasses, 0.5% feedlime and 0.5% salt on a dry matter (DM) basis. A protein concentrate consisting of 76.5% cotton oil cake and 23.5% fish meal was fed at 0.5, 1 and 1.5 kg per day to the LC, MC and HC group respectively from days 1 to 105 of lactation. The lactating cows grazed pasture allocated at 20 kg DM/cow/day consisting of 43% perennial ryegrass/clover, 24% annual ryegrass/oats, 14% lucerne, 15% kikuyu and 4% other pastures during the experimental period. The fat corrected milk (FCM) production per lactation of cows fed NC (0 kg/day), LC (2.4 kg/day), MC (4.8 kg/day) and HC (7.2 kg/day) was 3741, 4645, 4868 and 5282 kg (s.e.m. = 146), respectively. Cows fed the high level of concentrate (HC) produced significantly more FCM and butterfat than cows on the other treatments. The FCM production of cows on the LC and MC treatments did not differ from each other and both produced more FCM than the control treatment. Cows produced 1.25, 0.78 and 0.54 L of FCM for each kg of concentrate fed at the LC, MC, and HC levels of concentrate feeding over two lactations. Concentrate feeding had no significant effect on milk composition, live weight and intercalving period of cows. The condition score of cows improved as the level of concentrate feeding increased.

Palabras clave : Milk production; milk composition; grazing; intercalving period; condition score; live weight change; pasture quality.

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