Milk Production on Low-protein, Urea-rich Feed

Abstract. The influence of purified, protein-free feed with urea and ammonium salts as nitrogen sources (0-feed) and of non-purified, urea-rich, low-protein feeds (ULP-feed) on the sulfur metabolism of cows has been studied by determining the contents of sulfur fractions in faeces, urine, milk, blood and rumen fluid. The sulfur of 0-feed was composed entirely of inorganic sulfate. During balance trials the N:S ratio in the feed varied from 6.1 to 9.5, and the sulfur content from 0.22 to 0.31 % of the dry matter. In every trial (seven with 0-feed and two with ULP-feed), of five or seven days duration, the cows were in high-positive sulfur balance. The 0-cows excreted a greater proportion of their total sulfur output via urine than the ULP-cows. The excretion of inorganic sulfate sulfur, as a proportion of the urinary and faecal sulfur, was greater for 0-cows than for ULP-or NorP-cows (cows on normal, protein-rich feed); the opposite was the case with regard to the excretion of ester sulfate sulfur and neutral sulfur. The sulfur contents of milk and blood showed only minor inter-feed differences.The sulfate content in the rumen fluid of the 0-cow rose rapidly after the commencement of feeding and then fell quite rapidly. We conclude tentatively that in the rumen of the 0-cow hydrogen sulfide is generated so quickly that the whole of it cannot be used for the synthesis of sulfur-containing compounds, a considerable proportion of it being lost in eructations or excreted as inorganic sulfates in the urine.

“…1972, Ettala andKreula 1976). The amounts of certain free amino acids in the blood plasma of 0-and ULP-cows are much lower than the corresponding values in NorP-cows.…”

Section: Introductionmentioning

confidence: 84%

“…1972, Ettala and Kreula 1976. The composition of the feed varied to some extent from one balance trial to another.…”

Section: Methodsmentioning

confidence: 99%

Studies on the sulfur metabolism of cows on protein-free and low-protein feed

Matikkala

Kreula

1977

“…Those fed small amounts of protein and plenty of urea are called ULP-cows and the feed ULP-feed. Both of these feeds have been described in previous publications (Virtanen 1963, 1966, 1967, Ettala and Kreula 1976. Samples of faeces were collected at different stages of lactation from both feeding groups during a period of several years.…”

Section: Methodsmentioning

confidence: 99%

Studies on the nitrogen compounds of the faeces of dairy cows fed urea as the sole or partial source of nitrogen

Ettala

Kreula

1979

Abstract. The nitrogen compounds of the faeces of dairy cows on purified, proteinfree feed with urea and small amounts of ammcnium salts as the sole source of nitrogen (0-feed). on low-protein feed in which part of the protein was replaced with urea (ULPfeed) and on normal protein-containing feed (NorP-feed) were studied.The total nitrogen contents of the dry matter of the faeces were 2.5 dr 0.7 % on 0-feed, 2.4 dr 0.4 % on ULP-feed and 2.3 dr 0.6 % on NorP-feed. The proportion of urea-and ammonium nitrogen of the total nitrogen was 3.2 dr 2.4, 4.5 d: 2.4 and 3.7 dr 1.8 % respectively, and the proportion of nitrogen soluble in 70 % ethanol 10.9 dr 5.7, 9.9 ± 2.4 and 10.4 dr 3.8 % of the total nitrogen; the proportion of nitrogen in the free amino acid fraction was 4.1 d: 2.9 on 0-feed, 1.6 dr 1.4 (P < 0.05) on ULP-feed and 3.2 dr 2.9 % on NorP-feed.The nitrogen insoluble in 70 % ethanol as a proportion of the total nitrogen was 82.3 ± 7.2 on 0-feed, 85.4 dr 5.0 on ULP-feed and 82.3 dr 7.2 % on NorP-feed.Of the total nitrogen of this insoluble fraction, the following proportions were released as amino acids by acid hydrolysis: 62.15 ± 8.5 % on 0-feed, 61.6 d; 10.7 % on ULP-feed and 59.0 ± 13.9 % on NorP-feed. (t, e-diaminopimelic acid was 1.7 ± 0.6, 0.7 ± 0.2 (P < 0.05) and 1.2 ± 0,4 mol % respectively of the total amino acids of the hydrolyzate.The soluble nitrogen fraction was separated into free amino acid and »peptide» fractions, and the amino acid composition of both was determined, the latter after acid hydrolysis.

“…The feeding of these cows has been reported in detail in previous publications (Virtanen 1966, Virtanen et ai. 1971, Ettala and Kreula 1976. For comparison, the urine of cows on normal feed (NorP-cows) was also studied.…”

Section: Test Cows and Their Feedingmentioning

confidence: 99%

The effect of feeding on the hippuric acid content of cow’s urine

Kreula¹,

Rauramaa²,

Ettala³

1978

Self Cite

Abstract. The urinary hippuric acid contents of dairy cows on a purified, proteinfree feed (0-feed, 0-cows), as well as the effect of benzoic acid and aromatic amino acid supplements, and silage and hay supplements, on the urinary hippuric acid content, were followed in the present study. The hippuric acid contents of the urine of 0-cows were compared with those of a cow on low-protein, urea-rich feed containing hemicellulose (ULP-cow). and of normally-fed cows (NorP-cows).The urinary hippuric acid content of the 0-cows varied between 0.1 and 0.6 g/1 (n = 8). The proportion of hippuric acid nitrogen of the total urinary nitrogen Was 0.2 -0.9 %. The presence of hippuric acid in the urine of the 0-cows indicates an endogenic hippuric acid production within the cow. 0-feed is deficient in all exogenic precursors of benzoic acid. Addition of benzoic acid to the feed of 0-cow caused temporary rise in the hippuric acid contents of the urine, of aromatic amino acids the addition of tyrosine, besides benzoic acid, raised the urinary hippuric acid content by a highly significant amount.The urinary hippuric acid content of the ULP-cow was on average 6.7 g/1 (n = 42) and the proportion of hippuric acid on the total urinary nitrogen 5.2 %.The urinary hippuric acid contents of the NorP-cows were on average 11.9 g/1 (n = 14), and the proportion of hippuric acid nitrogen of the total urinary nitrogen 10.7 %. The difference in the urinary hippuric acid contents with 0-and NorP-cows is significant, as is also the difference in the proportions of hippuric acid nitrogen of the total urinary nitrogen with these cows.The difference in the hippuric acid contents of 0-and ULP-cows is also significant (P < 0.01). The same regards ULP-and NorP-cows (P < 0.01).