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Milk production performance of autumn-calving Holstein Friesian cows managed under flat-rate or feed-to-yield concentrate feeding systems
This experiment was conducted to examine the effects of two feeding systems, on milk production, body condition score and feed inputs of autumn-calving cows. Autumn-calving Holstein Friesian cows (n=84) were blocked pre-partum according to parity, body condition score, genetic merit for milk production, and assigned to one of two postpartum concentrate feeding systems; feed to budget (FTB) or feed to yield (FTY); FTB cows were allocated concentrate at a flat rate, and FTY were allocated concentrate based on individual milk production. Both feeding systems were offered 14.5 kg forage DM/cow/day during the winter housing period containing grass silage and maize silage (in the ratio 2:1) plus 3.0 kg DM of concentrate. Cows on the FTB treatment received a further 3.95 kg DM of concentrate in the milking parlour; cows on the FTY treatment received 0.43 kg DM of concentrate in the milking parlour, per kg of milk (based on the previous weeks mean milk production) exceeding a base milk yield 23.0 kg/cow/day. Cows were turned out to pasture on 10 February. During the main grazing period (March-September) pre-grazing herbage mass was 1300-1500 kg DM/ha (above 4 cm), and was grazed to a residual of <100kg DM/ha (target 4.0 cm). Where pasture supply was adequate, the FTY group was offered 0.43 kg DM concentrate per kg milk exceeding a base yield of 25.0 kg/day as described previously. When pasture supply was below the demand, additional concentrate (plus silage if required) was allocated at a flat-rate to both treatments. Data were analyzed using a mixed model procedure in SAS v9.3 which included a repeated measure for week of experiment. Concentrate feeding system had no significant effect on milk yield, milk solids production or mean BCS, during the indoor period or at grazing. In total the FTY treatment was fed 250 kg DM /cow less concentrate that the FTB (P<0.001). The ratio of concentrate fed per kg of milk output was lower for FTY which indicates improved efficiency of milk production from forage.
Keywords: Feed to yield: Pasture: Autumn calving