Feed intake of grazing cattle. IV. A study with milk cows of the influence of pasture restriction combined with supplementary feeding on production per animal and per acre

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Abstract
The possibility that restriction of pasture and controlled supplementation of the diet of milking cows with concentrates might improve the efficiency of utilisation of grazing was examined in a double reversal grazing experiment with 9 Ayrshire cows per treatment which extended over 4 months.Cows received either pasture alone allocated daily by electric fence (treatment B), or half the pasture area plus one-third of their expected DOM intake offered as concentrates (treatment A).In the first two periods, treatment A resulted in closer defoliation of the pasture.Over the whole experiment there was no significant difference in yield of fat-corrected milk between treatments, although treatment A depressed butterfat percentage and raised milk yield significantly. Treatments did not influence live-weight gain significantly and toth groups gained over the season.Feed intake estimated by chromic oxide-faecal index methods was similar for both treatments except in period 1. Intake estimates by clipping methods or by faecal index methods were in close agreement in period 1 for treatment B and in reasonable agreement in periods 2 and 3.The results are discussed particularly with a view to the possibilities of replacing some grazing with barley or other concentrated feeds. On the available evidence this is economically feasible only where very profitable uses of the grassland saved are possible.