Akademik Veri Yönetim Sistemi
LIVESTOCK SCIENCE, cilt.223, ss.184-192, 2019 (SCI-Expanded)
When crossbreeding with beef breeds in organic dairy herds, the use of non-sexed semen will results in both male and female offspring to be used for beef production. The objective of the present study was to compare growth and carcass characteristics of 15 Danish Holstein bull (HB) calves, 15 beef x Danish Holstein crossbred bull (CB) calves and 15 beef x Danish Holstein crossbred heifer (CH) calves reared under organic settings. As beef bred sire a high-merit bull of the Limousine breed was used. Furthermore, the study should generate knowledge which can support future organic beef production. Forty-five Spring-born calves were purchased at 10 private farms at approximately 20 days of age with an average initial body weight of 52.9, 58.2 and 56.1 (s.e.m. 2.6) kg for HB, CB and CH, respectively. Calves were housed indoors in groups of five until weaning off cow's milk at 3 months of age. Calves were gradually introduced to a grass-silage based ration from 3 to 4 months of age. From 4 to 7 months calves were kept on mixed grass pasture of ryegrass and white clover. From 7 to 13.5 months calves were housed indoor in groups of 5 and fed a mixed ration with low-moderate energy content. From 13.5 months of age, the established groups of 5 animals grazed in a rotational paddock system until slaughter at 17 months. There was no difference between HB, CB and CH in average daily gain (ADG) from birth to weaning, from weaning until turn-out and during pasture from 4 to 7 months. The ADG indoor from 7 to 13.5 months, and during pasture from 13.5 to 17 months differed between treatment groups. The CB had greater ADG than CH for both periods with HB being intermediate (P < 0.02-0.001). The ADG indoor from 7 to 13.5 months were 1.06, 1.10 and 0.97 (s.e.m. 0.02) kg d(-1), and ADG during pasture from 13.5 months until slaughter were 0.88, 1.11, and 0.64 (s.e.m. 0.07) kg d(-1) for HB, CB, and CH, respectively. Final body weights were heavier for CB, intermediate for HB, and lowest for CH (575, 534, and 480 (s.e.m. 12.1) kg, P < 0.01). Overall, ADG from arrival to slaughter was 21% higher for CB than CH (P < 0.001), and the average ADG of the combined heifer and bull crossbreds ((CB +CH)/ 2) was not different from that of HB. Crossbreeding improved EUROP conformation markedly in both CH (5.3) and CB (7.0) compared with HB (3.0) (P < 0.001), and carcass weight was 4% higher for crossbreds ((CB + CH)/2) compared with HB. There was no difference in EUROP fatness between HB and CB which was low (1.0-1.2), whereas CH had an acceptable fatness (2.9). Carcass lean:fat color (assessed using a Danish 1-5 scale) was high for the bulls (3.9-4.0) but acceptable for CH (3.3, P < 0.01). It is concluded that improvements in carcass conformation and carcass weight coupled with similar overall growth of the combined heifer and bull crossbreds support the efficiency of beef x Holstein crossbreds of both sexes compared with purebred Holstein bulls within an organic system with summer grazing. Furthermore, it proved difficult to finish intact bulls on pasture to fulfill a premium beef cut market that requires higher fatness and less dark meat color than obtained herein.