ALBERT

Description: SUMMARYThe effect of treating soya-bean meal with formaldehyde was studied in cattle by supplementing a hay–barley diet with two levels of either untreated or formaldehydetreated soya-bean meal. The formaldehyde treatment had no significant effect upon apparent N digestibility in the whole tract; it increased the amounts of non-ammonia N and amino acid N entering the small intestine but this increase was not statistically significant. However, increasing the proportion of either soya-bean meal in the diet increased the flow of non-ammonia N to the small intestine and apparent N digestibility in the whole tract. The formaldehyde treatment reduced the apparent degradability of the soya-bean meal N, determined in vivo from 0·74 for the untreated meal to 0·38 for the formaldehyde-treated meal. The in sacco technique produced values for the apparent degradability of the two soya-bean meals which ranked them in a similar manner as did the in vivo technique but gave lower values for degradability than the in vivo technique.

Description: SummaryA 4 x 4 latin-square design experiment was carried out to determine the effects of increasing nitrogen (N) intake by feeding diets containing increasing amounts of soyabean meal upon the digestion of organic matter (OM) and N by cattle equipped with rumen and duodenal cannulae. A basal diet (B) containing 600 g ground barley and 400 g grass silage/kg diet and three diets (BS1, BS2 and BS3) in which increasing amounts of the barley were replaced by soya-bean meal were fed. The mean daily intakes of OM and N when each diet was fed were 4·56, 4·55, 4·30 and 4·52 kg OM and 920, 114·7, 138·3 and 164·1 g N for diets B, BSl, BS2 and BS3 respectively.Neither the amounts of OM entering the small intestine nor those voided in the faeces were altered by the diets fed. Thus the mean apparent OM digestibility for all the diets fed was 0·74 + 0·013 and the proportion of digestible OM intake apparently digested in the rumen was 0·77 + 0048.Mean daily concentrations of ammonia N in the rumen were significantly (P 〈 0·001) increased from 38 mg N/l (diet B) to 129 mg N/l (diet BS3) as N intake increased.The quantities of non-ammonia N and of amino acid N entering the small intestine were not significantly (P 〉0·05) increased as more soya-bean meal was added to the diet, although diet BSl supported the greatest flows of N to the small intestine. Thus as more soya-bean meal was added to the diet there were increasing net losses of nonammoniaN(P 〈 0·01) and amino acid N (P 〈 0·01) prior to the small intestine. Faecal N excretion was not increased (P 〉 0·05) as soya-bean meal intake increased and thus apparent N digestibility was significantly (P 〈 0·01) increased by increasing soyabean intake.Both the quantities of microbial N entering the small intestine daily and the apparent efficiency of microbial N synthesis within the rumen were increased when diet BSl was fed in comparison with the basal diet (B) and then declined when diets BS2 and BS3 were fed; these increases were not significant. The quantities of feed N entering the small intestine daily were not significantly (P 〉 0·05) increased as soya-bean meal intake increased; thus apparent feed N degradability in the rumen was significantly (P 〈 0·01) increased as soya-bean meal intake increased. In contrast, the rates of disappearance of N from each of the components of the diets fed, when incubated in the rumens of the cattle in porous synthetic fibre-bags, were not increased (P 〉 0·05) as soya-bean meal intake increased.

Description: SummaryA 4 × 4 latin-square design experiment was carried out to determine the effects of increasing nitrogen (N) intake by feeding diets containing increasing amounts of fishmeal upon the digestion of organic matter (OM) and N by cattle equipped with rumen and duodenal cannulae. A basal diet (B) containing 600 g silage and 400 g ground barley/kg diet and three diets (BF1, BF2 and BF3) in which increasing amounts of the silage and barley basal diet were proportionately replaced by fishmeal were fed. The mean daily intakes of OM and N when each diet was fed were 4·29, 4·28, 4·22 and 4·20 kg OM and 90, 108, 125 and 143 g N for diets B, BF1, BF2 and BF3 respectively.Neither the amounts of OM entering the small intestine nor those voided in the faeces were altered by the diets fed. Thus mean apparent OM digestibility for all the diets fed was 0·74 ± 0·007 and the proportion of digestible OM intake apparently digested in the rumen was 0·83±0·011.Mean daily concentrations of ammonia N in the rumen were significantly (P

Description: SUMMARYThe effect of pretreating soya-bean and rapeseed meals with formaldehyde was studied. Soya-bean and rapeseed meals, both untreated and formaldehyde-treated, were fed to cattle receiving a basal diet of silage in a 4 × 4 latin square. Formaldehyde treatment of both meals significantly reduced apparent N digestibility. All four protein supplements increased the amounts of non-ammonia N and amino acid N entering the small intestine over those obtained when silage was fed alone. Formaldehyde treatment of the meals increased the amounts of non-ammonia N and amino acid N entering the small intestine; this effect was significant, however, for only the formaldehyde treatment of the soya-bean meal. The low efficiency of microbial N synthesis observed when silage was fed alone was increased by the inclusion of both of the soyabean meals in the diet but not by the inclusion of the rapeseed meals. Formaldehyde treatment reduced the apparent degradability of the soya-bean meal N, determined in vivo, from 0·90 for the untreated meal to 0·40 for the formaldehyde-treated meal; similarly the degradability of the untreated rapeseed meal was reduced from 0·77 to 0·41 by the formaldehyde treatment. The in sacco technique gave values for degradability for the protein supplements which ranked them in a similar manner as did the in vivo technique; however, for any one meal the in sacco value for degradability was lower than that determined in vivo.

Description: A ruminant animal is largely dependent upon microbial protein synthesized within the reticulorumen for amino acids to meet its requirements for maintenance and production. The major precursor for rumen microbial protein synthesis is ammonia arising both from degradation of feed proteins within the rumen and from nitrogen recycled to the rumen. The concentration of rumen ammonia-N required to sustain maximal rates of microbial protein synthesis in vivo has been variably reported to range from 22 to 235 mg ammonia-N/1 rumen fluid (Miller, 1982). Most experiments which have investigated the concentrations of rumen ammonia-N required for maximal rates of microbial protein synthesis have used the addition of urea to the diet as the means of increasing rumen ammonia-N concentrations. However, little attention has been paid to the effects upon rumen ammonia-N concentrations and upon the efficiency of rumen microbial protein synthesis of supplying increasing amounts of a readily degradable protein in the diet, although Beardsley et al.(1977) found that as increasing amounts of soya-bean meal were fed to sheep, net losses of N across the forestomachs of the sheep were increased. In this paper, two experiments are described in which increasing amounts of soya-bean meal were fed to sheep receiving a basal ration of rolled barley and hay; the digestion of organic matter (OM) and of amino acid N (AAN) within the rumen, the net quantities of microbial AAN entering the small intestine and the efficiency of rumen microbial AAN synthesis were measured.