Effects of a concentrate supplement on the intake and digestion of a low-quality forage by lambs

Doyle, PT; Dove, H.; Freer, M.; Hart, FJ; Dixon, R. M.; Egan, A. R.

doi:10.1017/s0021859600083702

Cited by 28 publications

(10 citation statements)

References 28 publications

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“…The gain in nitrogen between the mouth and duodenum observed when both diets were fed (Table 5) followed the general pattern reported in a number of investigations when low protein diets were fed to sheep (Egan et al 1975;Doyle et al 1988). However, in the current study, although crude protein and estimated RDP values were similar for both diets, a greater recycling of nitrogen was estimated when the animals were offered the asynchronous diet (B).…”

Section: Daily Degradationsupporting

confidence: 85%

Effect of synchronizing the rate of dietary energy and nitrogen release on rumen fermentation and microbial protein synthesis in sheep

et al. 1993

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S U M M A R YThe effects of two diets, formulated to be either synchronous or asynchronous with respect to the hourly supply of energy and nitrogen, on rumen fermentation and microbial protein synthesis were studied in sheep.In Expt 1, the in situ degradation characteristics of nitrogen (N), organic matter (OM) and carbohydrate (CHO) fractions were determined in winter wheat straw, winter barley, malt distillers dark grains, rapeseed meal and fishmeal. The feeds exhibited a large range in degradability characteristics of the nitrogen and energy-yielding fractions.A computer program was developed, based upon the raw material degradation characteristics obtained from the above studies. The program was used to formulate two diets with similar metabolizable energy (9-5 MJ/kg DM) and rumen degradable protein contents (96 g/kg DM) but to be either synchronous (diet A) or asynchronous (diet B) with respect to the hourly rate of release of N and energy. The program was used to predict the hourly release of N, OM and CHO and the molar production of volatile fatty acids (VFA).In Expt 2, the two diets were fed to four cannulated sheep at the rate of 1 kg/day in four equal portions, in two periods, using a change-over design. Rumen ammonia concentrations followed the predicted rate of N degradation. A maximum concentration of 105 and 7 mM for diets A and B respectively was achieved within the first hour of feeding which then fell to 7 and 3 mM respectively. Rumen VFA proportions were more stable for the synchronous diet (A) than the asynchronous diet (B) and were more stable than predicted for both diets. True ruminal degradation of OM and CHO was similar for both diets and close to that predicted, although fibre degradability in diet A was 30% lower than predicted due to a reduction in both cellulose and hemicellulose digested. Microbial protein production was estimated simultaneously with L-[4,5-3 H]leucine and a technique based on cytosine. Estimates varied with marker but mean values indicated a 27% greater production of microbial N (g N/kg DM I) with the synchronous diet (A) and an average improvement in microbial protein efficiency (gN/kg OM truly degraded or CHO apparently degraded) of 13%, although neither difference was significant. There was evidence of a greater recycling of N in the animals and a significantly lower content of rumen degradable protein when the sheep were fed the asynchronous diet (B).The results are consistent with the view that synchronizing the rate of supply of N and energyyielding substrates to the rumen micro-organisms based upon ingredient in situ degradation data can improve microbial protein flow at the duodenum and the efficiency of microbial protein synthesis.

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Section: Daily Degradationsupporting

confidence: 85%

Effect of synchronizing the rate of dietary energy and nitrogen release on rumen fermentation and microbial protein synthesis in sheep

et al. 1993

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“…The authors attributed this effect to an increased energy-dependent expulsion of protons at the lower pH and a diversion of energy from growth to non-growth functions. Although the mean rumen pH values in animals fed the diets in the current experiment were lower than that reported in a number of other studies (Doyle et al 1988;Weston 1988), the similarity between the hourly and mean rumen pH values in animals fed either diet suggests that a low rumen pH was not a major reason for the differences in microbial efficiency observed in the current experiment.…”

Section: Hourly Rumen Parameterscontrasting

confidence: 77%

Effects of synchronizing the rate of dietary energy and nitrogen release in diets with a similar carbohydrate composition on rumen fermentation and microbial protein synthesis in sheep

et al. 1995

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S U M M A R YThe effects of synchronizing dietary energy and nitrogen supply in diets with a similar carbohydrate composition on microbial protein synthesis and rumen fermentation were examined in sheep. Two diets were formulated to be either synchronous (diet S) or asynchronous (diet A) for the hourly release of nitrogen (N) and energy to the rumen. Diet S contained (g/kg) 425 g wheat straw, 400 g winter barley, 150 g rapeseed meal and 25 g minerals/vitamins and diet A contained 505 g wheat straw, 458-5 g winter barley, 11-5 g urea and 25 g minerals/vitamins. Both diets were fed at the rate of 1 kg/day in four equal portions, to four cannulated sheep, in two periods in a change-over design.Rumen ammonia concentrations followed the predicted hourly trend in N degradation with a peak 1 h after feeding of 10 mM for diet S and 16 mM for diet A before falling within 3 h of feeding to 4 ITIM in animals fed either diet. Rumen volatile fatty acid (VFA) concentrations followed the cyclical trend predicted by stoichiometric equations, whilst rumen VFA ratios were more stable than predicted in animals fed either diet. The observed content of rumen degradable protein and organic matter truly degraded in the rumen was similar for both diets. The increase in total CHO digested in the rumen observed with diet A (427 g/kg DM) compared with diet S (364 g/kg DM) can be attributed to the greater content of starch in the asynchronous diet, which had a high degradability. The efficiency of microbial protein synthesis (g N/kg OM truly degraded in the rumen) was 11-20% greater in animals fed the synchronous diet (S) than the asynchronous diet (A). It is concluded that microbial N production was more efficient when dietary energy and N supply were synchronized.

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“…The oat straw (cv. The failure of supplements containing soya-bean meal to improve the voluntary intake of straw may have been because the rate of digestion and transfer of undigested residues to the abomasum were adversely affected by the rolled barley (Campling, 1966;Doyle, Dove, Freer, Hart, Dixon and Egan, 1988). These straw-only diets probably provided daily about 30 MJ metabolizable energy (ME) and were not sufficient to meet the maintenance requirement of a 300-kg heifer which is 38 MJ ME (ARC, 1980).…”

Section: Discussionmentioning

confidence: 99%

Energy and protein supplements to straw-based diets for yearling cattle: effects on straw intake and digestibility

Al-Saghier

Campling

1991

Anim. Sci.

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A series of change-over experiments examined the intake and digestibility of straw-based diets in yearling dairy heifers. Voluntary intakes of straws given as the sole food to yearling dairy heifers were 1-28, 1-20 and 0-90 kg dry matter (DM) per 100 kg live weight for barley, wheat and oat straws respectively, and the corresponding digestibility of organic matter was 0-47, 0-53 and 0-48. When supplemented with 2 kg rolled barley the intakes of straw did not alter, nor were they affected by replacing part of the rolled barley with an equal amount of soya-bean meal and thus increasing the dietary concentration of protein from about 50 to 110 g/kg DM. The use of molassed sugar-beet pulp in place of rolled barley reduced the intake of straw. Flaked maize promoted slightly higher intakes of straw than an equal amount of coarsely milled maize. Replacing rolled barley by lucerne hay reduced straw intake. It is estimated that, to provide sufficient energy and protein for a daily gain of 0-5 kg, heifer straw-based diets would require a supplement of 1-2 kg rolled barley and 0-8 kg soya-bean meal.

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Effects of a concentrate supplement on the intake and digestion of a low-quality forage by lambs

Cited by 28 publications

References 28 publications

Effect of synchronizing the rate of dietary energy and nitrogen release on rumen fermentation and microbial protein synthesis in sheep

Effect of synchronizing the rate of dietary energy and nitrogen release on rumen fermentation and microbial protein synthesis in sheep

Effects of synchronizing the rate of dietary energy and nitrogen release in diets with a similar carbohydrate composition on rumen fermentation and microbial protein synthesis in sheep

Energy and protein supplements to straw-based diets for yearling cattle: effects on straw intake and digestibility

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