Fertility fall? Check deficiency

After a challenging grazing season, producers should be on the lookout for vitamin and mineral deficiencies, which could lead to a reduction in fertility rates

What do you do if fertility rates drop month after month? Vitamin and mineral analysis might be the answer, particularly for a Somerset couple whose herd fertility rates have risen from below 50% to 85% in less than a month.

For Castle Cary-based contract dairy heifer replacement rearers Keith and Ann Hoskin, fertility rates started dropping in May, with August bringing levels which, at below 50%, were worrying.

“We couldn’t understand it,” says Mr Hoskin. “Diet was the same, a ration of 3kg a head of an 18% protein specialised heifer concentrate with ad-lib straw.

“Feeding straw is right for our system and despite high prices this year, we feel the ration mix developed produces the right conformation of dairy cow for our customers.

“It was near impossible to notice any usual signs of heat, which was unusual, as we keep a close eye on small groups. Despite the fertility issues, there were no visible signs indicating loss of condition,” adds Mrs Hoskin.

Rearing anything up to 330 heifers for four dairy farms and using a mix of Devon stock bull and AI service, the first step the couple took, with the help of vet Paddy Gordon from Shepton Veterinary Group, was to analyse methods of conception.

“It was either me or the bull to be shot,” jokes Mr Hoskin. “We serve animals at a minimum of 380kg with either AI or the bull depending on what the customers want.”

When no discrepancy showed between rates gained from either AI or the bull, other factors had to be considered. “We did tests for worm burden, lepto and PhB levels in blood to assess whether nutrition was correct,” he adds.

After a rigorous quarantine and vaccination process, animals are vaccinated for IBR on arrival, with worming and Lepto/BVD vaccines advised, but dependent on client stipulations. Heifers are then vaccinated against husk in the spring.

“When animals have gone through quarantine and have settled in we split them to matched groups of 20 or less,” says Mr Hoskin. “We can then tailor rations to suit size and animals do better for this.”

Aiming for a daily liveweight gain of 0.8-0.85 and a period of 16 months to the target weight of 380kg, animals are bred for ease of calving first and foremost, with factors such as yield and type being negotiated with the customer.

“We aim to produce what the customer wants, as long as this does not compromise the health status of the herd. Attention to detail is key in achieving this and by keeping strict records we are able to analyse all aspects when necessary.”

Plasma copper levels were found to be only marginally low according to Bristol Vet School levels, but this was enough to alert Mr Gordon that this may be what was affecting fertility.

“Combining what we already knew of the situation, a clinical judgement was made to treat it as a copper deficiency,” he says.

A 2ml subcutaneous injection of Coprin, containing 100mg calcium copper edetate, was given to anything due to be served and animals which had just been served to correct deficiency and keep foetuses alive, he explains.

“The effect was almost instantaneous. Four animals came bulling in the first week and animals were showing far clearer signs of heat,” adds Mr Hoskin.

PD-ing animals five weeks later, fertility rates were up to a respectable 85%, with results equal for both those served by AI and naturally.

“Copper deficiency is a perennial problem, particularly in the Somerset levels and low lying areas. Spring conditions this year mean higher chance of problems connected to deficiencies, which in the case of the Hoskins was a more than probable cause,” adds Mr Gordon.