Hybrid vigour benefits cow health, fertility and survival
WHILE CROSSBREEDING is not for everyone, for many producers it offers benefits and milk output can be maintained, as is becoming clear from research carried out in the USA.
Les Hansen from the University of Minnesota stressed that pedigree breeders with an interest in improving their cattle should not switch to crossbreeding. They will benefit from genetic improvement.
FREE GIFT
“But for cows that are just milking machines, crossbreeding is a free gift. Theoretically, hybrid vigour offers a 6.5% increase above the average production of both breeds for the first cross and at least 10% improvement in health, fertility and survival.
“He told delegates at the conference in Shropshire there was a growing interest in crossbreeding in the USA. This is occurring as milk pricing favours milk solids and to improve calving ease – which has an impact on other health traits.
Cow fertility is also declining and cows are often too large for cubicles. “And there is mounting concern about inbreeding, which has doubled in the Holstein breed worldwide since 1990.
“That’s why his university began a study on seven Californian dairy farms, using three different sire breeds across their pure Holstein cows. These were Normande, Montbeliarde and Scandinavian Red sires. About 1400 heifers have now calved in the ongoing study.
Results available to date for cows calved June 2002 to December 2003 already show the benefits of crossbreeding, with the improvement in survival rates clear in first lactations. By 305 days in milk only 86% of Holsteins were still in herds compared with 92-93% for the crosses, most losses were for health reasons.
Differences in fertility were also appearing from the number of cows calving within 20 months, although only enough Normande crosses – which were used in herds first – could be compared, added Dr Hansen. “Just 66% of Holsteins had calved again, whereas 82% of the Normande crosses had calved for a second time.
“So far, milk yields are only reported at up to 150 days into lactation to save penalising the crossbreds – more of which were back in-calf causing yield to start reducing. But this shows two crossbred groups outyielding pure Holsteins on fat and protein output (see table).
Dr Hansen added that heifers with fewest calving difficulties, the Scandinavian Reds, produced the highest yields in these results (see table). Further yield information will be reported when more data is available.
Conception rates to first service were also markedly improved for crossbreds, said Dr Hansen. For Holsteins the conception rate was just 22%, but for crossbreds it was 30-35%, with Normande crosses the highest and Scandinavians the lowest. “Figures for days open show about three weeks difference between the purebreds and crossbreds. That’s a whole heat cycle.”