The Effects of Feeding Level and Protein Source of the Diet on Growth and Development at Slaughter of Pre-Pubertal Heifers
Titel:
The Effects of Feeding Level and Protein Source of the Diet on Growth and Development at Slaughter of Pre-Pubertal Heifers
Auteur:
Mantysaari, Paivi
Verschenen in:
Acta agriculturae Scandinavica. Section A, Animal science
Paginering:
Jaargang 43 (1993) nr. 1 pagina's 44-51
Jaar:
1993-02-01
Inhoud:
The effects of feeding intensity and protein source on growth, feed intake, slaughter and body measurements of 24 pre-pubertal Finnish Ayrshire heifers were studied. The heifers were fed a hay-barley diet supplemented with either urea or rapeseed meal (RSM). The treatments were: (1) LU, low feeding level+urea; (2) LR, low feeding level+RSM; (3) HU, high feeding level+urea; (4) HR, high feeding level+RSM. Hay was fed ad libitum on HU and HR diets but was restricted on LU and LR diets. The average initial weight of the heifers was 87 kg, and the final weight 220 kg. There was a significant interaction between feeding level and protein source for growth and feed intake measurements, but not for slaughter quality. Protein source had no impact on the daily gain on low feeding intensity (692 vs. 655 g/d). On high feeding intensity the heifers grew 890 g/d and 805 g/d (P <0.01) on the HR and HU diets, respectively. The carcass quality was not affected by the feeding level or protein source, but the heifers on LU and LR diets had bigger frame size at the live weight of 220 kg than heifers on HU and HR diets. The results suggest that on the low feeding level the quality of the protein was not critical for heifers weighing under 220 kg. However, on the high feeding level, the growth rate was increased when RSM was used instead of urea as protein supplement. Based on calculations done according to the Nordic protein evaluation system this is proposed to be due to the increased supply of absorbed amino acids with RSM compared to urea supplementation.
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