The influence of nutrition in early lactation on the performance of spring-calving suckler cows and their calves

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Abstract
Twenty-four Hereford × Friesian cows (HF) and 24 Blue-Grey (Whitebred Shorthorn × Galloway) cows (BG) were housed in individual stalls. For the last 12 weeks of pregnancy they were fed hay to supply 75% of estimated maternal maintenance energy requirements. From calving (11 February to 9 April) until turning out to graze on 15 May they were given hay for maintenance, and a concentrate sufficient for either 2·25 kg (L) or 9·0 kg (H) milk per day, balanced within genotype. From 15 May until the end of the experiment on 7 September the cows and calves grazed as a single herd in a paddock grazing system, at a controlled daily herbage allowance of 50 g dry matter, measured to ground level, per kg total weight of cows and calves.Cows on Treatment L lost more weight between calving and turnout than those on Treatment H, gave less milk, and their calves grew more slowly and were lighter at turn-out. Milk yields increased substantially after turn-out. Subsequently, milk yields and calf growth rates, and herbage intakes by the cows, did not differ significantly, although all were marginally higher for animals previously on Treatment L. Final calf weights, cow weights and cow body condition scores did not differ significantly.Calves from HF cows were heavier at all stages than calves from BG cows. HF cows were heavier at calving than BG cows, gave more milk (though the difference was not significant) and lost more weight in early lactation. Final live weights and condition scores did not differ significantly.The limited evidence suggested that conception to artificial insemination following oestrus synchronization was not affected by plane of nutrition in early lactation.