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The influence of dam genotype, originating from either dairy or suckler herds, on maternal and offspring traits has been studied using 43 suckler herds in Northern Ireland.
Participants were The Agricultural Research Institute of Northern Ireland and Penn State University, USA ( Kirkland, Keady, Ingram, Steen, Comerford, Patterson and Mayne).
Recorded data included dam genotype, calving details and incidence of dystocia. Cow fertility was assessed as "re-appearance rate", a measure of whether or not a cow had produced another calf within specified periods post calving. Carcass weight, conformation and fat classification were recorded for all progeny. Ages at slaughter and carcass values were calculated.
Data were collated into four specific groups based on dam genotype, as follows: Angus or Hereford x Friesian; Continental x Friesian; Angus or Hereford x Continental and ¾ or greater Continental bred cows.
Fertility tended to be lower with ¾ or more Continental cows. Only small differences in dystocia were recorded between the dam genotype groups.
Results showed that carcass conformation was superior with Angus or Hereford x Continental, or ¾ or more Continental dams, compared with dams containing Holstein-Friesian genes.
The use of early maturing beef x Friesian dams resulted in progeny with lighter, fatter carcasses and lower carcass value.
It was concluded that Continental x Holstein-Friesian dams produced progeny with similar carcass weight and value to ¾ or more Continental cows.
The potential of ten of the most common dam genotypes used for beef production was also studied to assess the effect of individual dam genotype.
Using the same 43 suckler herds, herd owners were asked to record genotype and calving difficulty. Cow fertility was assessed as "re-appearance rate", a measure of whether or not a cow had produced another calf within specified periods post calving.
Genotypes studied were Angus, Angus x Holstein-Friesian, Charolais, Hereford x Holstein-Friesian, Limousin, Limousin x Holstein-Friesian, Limousin x Simmental, Simmental, Simmental x Charolais and Simmental x Holstein-Friesian.
Angus and Limousin cows tended to have lower scores for dystocia than other genotypes. Simmental dams had higher dystocia scores than Limousin x Friesian but differences between other breeds were non-significant.
Dam genotype had no significant effect on re-appearance rate at 390 days. However, by 450 days the reappearance rates of Limousin x Holstein-Friesian dams were higher than for Charolais, Simmental and Limousin dams. Also, Angus x Holstein-Friesian dams had higher reappearance rates than Limousin dams.
Carcass conformation was poorest in progeny from Simmental x Friesian, Angus, and Hereford x Friesian dams. Carcass fat classification showed a small range across dam breed types though progeny of Limousin dams had lower fat class scores than progeny of all other breeds with the exception of those from Limousin x Simmental and Charolais dams. Progeny of Angus x Friesian tended to have higher fat class scores than several other breeds.
Progeny carcass weight and value differed by 17kg and £33 respectively between dam genotypes. Progeny of mainly Continental dams and Limousin x Holstein-Friesian dams tended to realise the highest values.
It was concluded that Limousin x Holstein-Friesian and Simmental x Charolais dams produced progeny with high value carcasses, and also had good reappearance rates.
Re-appearance rate at 390 days was low for all breeds indicating a major fertility problem in suckler herds.
Findings were given at the British Society of Animal Science Annual Conference, 5-7 April, York.