Effect of slaughter weight and intensity of feeding on growth, utilization of feed, quality of carcass and of meat in bulls and bullocks

Andersen, H.R.; Ingvartsen, K.L.; Buchter, L.; Kousgaard, K.; Klastrup, S.

Beretning fra Statens Husdyrbrugsforsog 544: 145


Accession: 001189532

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In Denmark in 1976-80 there was a 2 x 4 x 4 factorial trial with 72 male and 48 castrated cattle initially 73 days old, fed freely or given 85 or 70% of free intake, or given 70% until the cattle were 125 kg less than the proposed bodyweight and then fed freely. Cattle were killed at 425, 550, 675 or 800 kg bodyweight. Cattle fed freely ate 10 to 20% more than expected. Daily gain of bodyweight for males was greatest between 250 and 400 kg bodyweight. Higher final bodyweight gave higher dressing percentage and better conformation, but a higher feed conversion ratio. From 100 to 400 kg bodyweight the feed conversion ratio increased linearly at 1.3 Scandinavian feed units (SFU)/kg for every 100 kg bodyweight increase. After 400 kg bodyweight it increased more rapidly. Dressing percentage increased by about 1.1 percentage units and conformation by 0.5 points for 100 kg bodyweight increase. Increased feeding gave a shorter fattening period, higher dressing percentage and better conformation than those of males fed moderately, but it gave poorer feed conversion and the risk of over-fat carcass for males over 425 kg. For each 100 g daily gain caused by increased feeding, an increase in feed conversion ratio of about 5% could be expected for males given 75 to 100% of maximum intake. That was about 70 SFU for a male of 400 kg. The 100-g gain increased dressing percentage by about 0.5 percentage units and conformation by 0.4 points. Advantages of increased feeding generally economically outweighed the disadvantages, and it was recommended that cattle be fed freely. Castration decreased the average daily gain; it did not affect dressing percentage or conformation of cattle of the same bodyweight and feeding rate. Castrates had more fat than males, especially at greater bodyweight. From 2 or 3 months old to 500 to 600 kg, daily gain for castrates could be expected to be 18% lower with high feeding rate and 12% lower with moderate feeding rate, than for males; their feed conversion ratio was 24% and 18% higher than that of males. Castrates fed moderately and gaining about 800 g daily should have the same feed conversion ratio as males fed freely and gaining 1200 g, calculated to the same final bodyweight. Longer growth period and higher feed conversion ratio of castrates meant that they could seldom give as high an economic return as males. Cattle over 2 or 3 months old, restricted then fed freely, took an equal amount of energy and grew as fast as cattle fed freely throughout growth. Carcass quality was better than that of cattle restricted throughout growth. Dressing percentage and fat content were lower but conformation was nearly equal to that of cattle fed freely.