FRESH insights into the nutritional requirements of replacement heifers were presented to delegates at a recent meeting on September 15, organised by AHDB Beef and Lamb and held at Arncliffe Farms, near Northallerton.

Australian scientist, Dr Viv Perry, carried out research on 24-month calving heifers during the various stages of pregnancy. The results indicated that dystocia (calving difficulty) was more common among animals fed a low-quality diet in the first two trimesters, followed by a high level of nutrition in the third trimester.

Good nutrition in the second trimester had the potential to increase weaning weights by as much as 30kg and was also associated with an increased birth weight averaging 8 per cent, she said.

“The heifers, which started out with the poorest body condition score at conception and early pregnancy, but then went on to gain condition in late pregnancy were the group that had the highest calf birth weights and required the greatest number of assisted calvings,” said Dr Perry.

"The first 90 days of foetal development is critical. The amount of protein fed to the heifer significantly changes the developing organs and musculature. A poor diet means fewer nutrients for the foetus and it will then signal to the dam that a higher level of nutrition is required. This will increase the size of the placenta.

“So the take-home message is to make sure that heifers have access to a good-quality, high protein ration when they are running with the bull and feed to maintain a steady rate of growth throughout the pregnancy.”

The effect of feeding during pregnancy on the subsequent fertility of the heifer was another area that came under investigation, she added.

“Body condition score at calving will have a direct influence on the onset of the following ovulation. A target body condition score of three for both heifers and cows should be set for the six-week period prior to calving.

"It is common practice to feed straw in the run-up to calving, with the aim of limiting calf size, but our findings show that straw should not be the main energy source at this stage; it can have a negative effect on both colostrum quality and calf survival.”

Dr Perry also stressed the importance of cleanliness in calving pens.

“Calves born into an environment heavily contaminated by faeces may ingest bacteria before they have received colostrum. This is likely to result in increased antibiotic use, higher veterinary bills and a reduction in weight gain,” she said.

The research was funded by the AHDB in the UK and its Australian counterpart, ARC (Australian Research Council).