Protein content in the diet for fattening lambs. 2. The chemical and amino acid composition of the body and utilization of amino acids apparently absorbed in the small intestine

Abstract

The chemical and amino acid composition of the empty bodies of 4 lambs slaughtered before fattening and of 12 lambs from 3 gropus (4 in each group) fattened for 113 day with a diet containing 17 (H), 14 (M) or 11%(L) crude protein were determined. The amount of nitrogen and individual amino acids apparently absorbed in the smali intestine during fattening was calculated on the basis of data on their passage to the duodenum and digestibility in the smali intestine. No differences were found in empty body composition depending on the protein content of the diet. The mean daily deposition of protein in the empty body was: 29.7,31.4 and 27.3 g in groups H, M and L, respectively. The utilization of protein for deposition into the empty body weihgt rose (P<0.01) from about 18 to 27% when the protein content was decreased from 17 to 11%. The utilization of metabolic energy available for growth (Ki) was best in group M and amounted to 0.41 in comparison with 0.38 and 0.33 in groups H and L, respectively. The lowering of the protein level in the diets improved the efficiency of utilization of amino acids absorbed in the smali intestine for their deposition in the empty body weight. Essential amino acids and semi-essential amino acids were best utilized by lambs from group M. From all of the amino acids, cystine and glycine were utilized best, with cystine being utilized better in groups H and M than in L. Reducing the protein content in group L to about 11 % resulted in decreasing the percentage of essential amino acids in protein deposited in the body, especially in comparison with the group fed diet M.It seems that the most effective utilization of protein takes place at a 14% crude protein content in the diet.

Effect of dehydrated lucerne on lamb performance and protein and energy deposition in the body

“…This fact may confirm the findings of some researchers who indicate that the chemical composition of EBW of lambs slaughtered at the same body weight is relatively stable and only slightly dependent on experimental factors (ARC, 1980;Urbaniak and Potkański, 1987;Fixet al, 1988). The content of dry matter, protein, fat, ash and energy deposited in EBW of lambs in the present study was similar to that found in other investigations carried out on lambs of the Merino type (Fix et al, 1988;Pająk et al, 1992;Urbaniak and Potkański, 1987).…”

“…The observed tendency was similar as in the case of utilization of ME for growth and production results. The quantity of protein deposited by lambs corresponded with the N retention in growing sheep in the experiments of 0rskov and Grubb (1979) and Amos and Evans (1980), 4.6-6.2 and 3.7-6.2 g/d, respectively which was determined by traditional methods (collection of faeces and urine), as well as with the results of studies by Urbaniak and Potkański (1987) and Pająk et al (1992) in which the comparative slaughter technique was employed.…”

Fattening performance of Polish Lowland lambs related to protein level in the diet

“…The earlier studies carried out at Jablonna (Jayaprakash, 1984;Paj^k et al, 1992) have shown that Polish Merino lambs fed during fattening period a diet containing 14.5% crude protein in dry matter showed a similar gain as those receiving a diet containing 16-17% crude protein, as recommended by Polish feeding standards. Reduction of the protein level in the diet also had no effect on the chemical composition of the empty body or the empty body gain, while protein utilization was improved.…”

“…Slaughter analysis, chemical analysis of the feeds and empty body of the lambs as well as calculation of the energy value of the body weight gains and protein utilization were carried out as described previously by Paj^k et al (1992). Preparation of separable fat for analysis was modified: the fat was placed in sealed polyethylene bags and frozen to a temperature of -18°C for 3-4 hours and ground twice immediately after removal from the freezer.…”