A Study On Maturity Of Chinese Yellow Cattle

This paper was designed to improve the accuracy of carcass ossification maturity for Chinese yellow cattle by comparing ossification maturity with dentition-based maturity, determining bone composition of spine vertebral featherbones and observing the microstructure of thoracic button at .different ages and degrees of ossification. The innovations were as follows: Firstly, the observation of corresponding relationship, based on ash percent of fresh thoracic buttons, between the degrees of ossification and dentition-based maturities; secondly, the knowledge of ossification characteristics of thoracic buttons with age change by the method of SEM (scanning electron microscope).The first part: The dentition-based maturities and ossification maturities (both CHN and USDA) of 1204 Chinese yellow cattle of different breeds were determined on the slaughter-line and the quarter-line. The degree of agreement between ossification maturitysystem and dentition-based maturity system was analyzed by means of kappa statistics and McNemar's lest. (1) Among 1204 Chinese yellow cattle, the dentition-based maturities of 29.2% were up to 24 mo, and the ones of 96;7% were up to 72 rno, with the average 41 mo. (2) The CHN ossification maturities' of 55.1% carcasses and the USDA ossification maturities of 60.8% agreed with dentition-based maturities, respectively. The degrees of agreement between CHN ossification maturity and dentition-based maturity were 40.3% up to 24 mo and 61.3% above 24 mo. And crossbred (60.4%) and Qinchuan (58.8%) cattle had higher degrees of agreement between CHN ossification maturity and dentition-based maturtiy than Luxi (46.4%). The degrees of agreement between USDA ossification maturity and dentition-based maturity were 88.3% up to 30 mo and 45.3% above 30 mo. And crossbred cattle (76.3%) had the highest and.Qinchuan (48.9%) the lowest with Luxi (58.3%) an intermediate agreement between USDA ossification maturity and dentition-based maturity. (3) The Kappa statistics (overall kappa values were 0.42 and 0.43 respectively) indicated that both CHN and USDA ossification maturity systems agreed moderately with dentition-based maturity system: McNemar's tests showed that differences existed between ossification maturity systems and dentition-based maturity system. CHN ossification maturities of carcasses up to 48 mo of age tended to be larger than dentition-based maturities, while carcasses above 48 mo of age tended to have smaller CHN ossification maturities than dentition-based maturities. And USDA ossification maturities of carcasses within 30 to 72 mo of,age were inclined to be smaller than dentition-based maturities, while carcasses above 72 mo of age tended to have larger USDA ossificaiton maturities than dentition-based maturities. (4) After combination of maturities A and B of CHN ossification maturity system, a great increase occurred in the agreement between CHN ossification maturity system and dentition-based maturity system. In the view of the effect of breed type on the ossification maturity, it is necessary to consider the color and shape of the ribs as an assistant indicator when we determine theossification maturity.The second part: Two hundred and five sacral featherbones, lumbral featherbones, and thoracic buttons from 69 Chinese beef carcasses were used to determine the content of bone ash, calcium, and phosphorus by the method of titration with potassium permanganate volumetric standard and with colorimetry. On a fresh weight basis, ash percent, calcium percent, and phophorus percent in sacral and lumbral featherbones had a tendency to increase with physiological maturity, but there was no statistically significant difference (P>0.05). Bone ash percent, calcium percent, and phosphorus percent in fresh thoracic buttons increased linearly with physiological maturity. On a bone ash basis, calcium percent, phosphorus percent, and calcium to phophorus ratio in sacral and lumbral featherbones kept relatively constant, but those in thoracic buttons varied greatly. Based on bone ash per...