Cattle handling at abattoirs. 3. The effects of feeding, and of different feeds, during the resting period before slaughter on liveweight carcasses and muscle properties

Abstract

The effects of feeding lucerne hay or rice straw during the resting period before slaughter on live, carcass and liver weights, bruising, the percentages of condemned head and tongues and of rumens with ingesta spillage, and muscle properties of cattle were examined. The 217 British breed and 70 Brahman steers (mean liveweights of 582 and 603 kg) had been grazing native pastures in northern Queensland. They were transported 440 km by road to an abattoir.The seven groups (each 41 steers) had access to water from unloading at the abattoir (late day 2) until slaughter. Three groups (N2, N4 and N6) were not fed, while two groups were fed ad libitum rice straw (RS4 and RS6) and another two groups were fed ad libitum lucerne hay (LH4 and LH6) from day 3 until 24 h before slaughter. The period from mustering to slaughter was 2 days for group N2,4 days for groups N4, RS4 and LH4, and 6 days for N6, RS6 and LH6.Unfed steers lost 4.7% of their pre-transport liveweight after 3 days and 9.1% after 5 days, while the fed steers lost 34% and 6.7%, respectively.Group N2 had a heavier (P<O.05) mean carcass weight than groups N4, RS4, RS6 and LH6 (351 kg compared with 343-344 kg). Both N2 and LH4 (348 kg) were heavier (P< 0.05) than group N6 (340 kg). Trends in mean dressing percentage were the same as for carcass weight. Group N2 had a heavier (P< 0.05) mean liver weight than all other groups, with no effect of feeding treatment. Group N2 and the fed groups (except RS6) had a greater (P< 0.05) mean water content for the M. longus colli than groups N4 and N6.Treatment had no significant effect on mean bruise score, fat thickness, mean pH value of M. longissirnus dorsi 24 h post mortem, the percentage of carcasses with high (>6.00) pH values, and the percentages of heads and tongue condemned due to ingesta contamination and rumens contaminated with ingesta spillage.