Quantitative digestion of fresh herbage by sheep: II. The sites of digestion of some nitrogenous constituents

MacRae, J.C.; Ulyatt, M. J.

doi:10.1017/s0021859600059207

Cited by 130 publications

(57 citation statements)

References 13 publications

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“…voluntary intake (Ulyatt et al 1977), to an enhanced supply of absorbed protein (MacRae & Ulyatt, 1974;Ulyatt et al 1980;Beever et al 1985) and to an enhanced utilization of metabolizable energy (ME) for growth and fattening (Joyce & Newth, 1967;Rattray & Joyce, 1974).…”

Section: S B C a M M E L L A N D O T H E R Smentioning

confidence: 99%

The efficiency of energy utilization in growing cattle consuming fresh perennial ryegrass (Lolium perenne cv. Melle) or white clover (Trifolium repens cv. Blanca)

et al. 1986

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I . Twenty Friesian steers (225 kg live weight) were fed on mid-(M) (June-July) and late-(L) (AugustSeptember) season crops of either fresh perennial ryegrass (Loliumperenne cv. Melle) (G) or white clover (Trifolium repens cv. Blanca) (C). Each of the forage diets was offered at three restricted planes of nutrition above maintenance to compare the effect of forage species on the efficiency of energy utilization. All diets were harvested daily from swards of regrowth forage of intended equivalent digestibility.2. Faecal and urine excretions were measured for 7 and 5 d respectively, followed by two consecutive 24 h measurements of methane, carbon dioxide and oxygen exchange in open-circuit respiration chambers.3. The apparent digestibility of the energy in perennial ryegrass (0.759) was marginally higher (P < 0.01) than that in white clover (0.748); the mid-and late-season forages were of similar ( P > 0.05) digestibilities. Metabolizable energy (ME):digestible energy (DE) in diet G (0.837) was significantly ( P < 0,001) different from that in diet C (0.812). The partition of energy losses when expressed as MJ/GJ gross energy intake (GEI) indicated that energy lost as methane was not significantly different ( P > 0.05) either between forages (G 62.8, C 63.4) or between seasons (M 63.2, L 63.1). Energy excretion in urine was higher for cattle fed on diet C (77.5) compared with diet G (60.5) ( P < 0.001). Heat production was similar (P 0.05) between forages (G 480, C 478), but lower (P < 0.01) for L (471) compared with M(486). Energy retention (by difference) was lower ( P < 0.001) for diet C (132) than G (156) and for M (138) than L (149) (P < 0.05). 4.Parallel-line analysis of unscaled ME intake (MEI) in relation to retained energy (RE; MJ/d) indicated that the efficiency of utilization (k,) was similar (P > 0.05) between perennial ryegrass (0.42) and white clover (0.46).Linear extrapolation of the values to zero energy retention indicated that maintenance requirements of ME (&,; MJ/d) were 23.3 for diet G and 28.8 for diet C. The extrapolated Em when expressed in relation to a measured fasting heat production (FHP) of 22.8 (MJ/d) resulted in a derived efficiency of utilization of ME for maintenance (k,) of 0.97 (G) and 0.79 (C), suggesting an underestimate of Em for diet G.5. Asymptotic exponential curves (representing the law ofdiminishing returns) were fitted to the unscaled values, ME1 and RE (MJ/d), and extrapolated to zero energy retention and zero energy intake. The derived estimates of FHP (MJ/d) 18.0 (G) and 22.0 (C) were not significantly different (P > 0.05) from the observed value of 22.8 MJ/d. Using the measured FHP as additional data points, the exponential model accounted for significantly more variance (P < 0,001) compared with the linear regression method of analysis. Exponential analysis resulted in estimates of Em (MJ/d) of 29.04 for diet G and 31.80 for C. The k , for each forage was calculated, assuming linearity of response, as 0.78 (G) and 0.72 (C). The calculation of k, at fixed positions o...

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Section: S B C a M M E L L A N D O T H E R Smentioning

confidence: 99%

The efficiency of energy utilization in growing cattle consuming fresh perennial ryegrass (Lolium perenne cv. Melle) or white clover (Trifolium repens cv. Blanca)

et al. 1986

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“…The estimated quantities of amino acids absorbed from the small intestine, calculated by applying the equations of MacRae & Ulyatt (1974) to N intakes, were respectively 85% and 110% of those required to support the levels of milk and wool production that were actually attained by the control and infused ewes (Table I).…”

Section: Voluntary Intake and Live-weight Changementioning

confidence: 99%

“…Recent New Zealand research has highlighted the high degradation r~tes of proteins from fresh pasture plants in the rumen, and indicated that the quantity of amino acids absorbed from the small intestine may be a limiting factor where high levels of production are required from ruminants fed fresh pasture species (MacRae & Ulyatt 1974). The present experiment was designed to test this hypothesis through feeding animals high-quality fresh pasture ad libitum and infusing soluble protein into the abomasum of half the group.…”

Section: Introductionmentioning

confidence: 99%

Responses to abomasal infusions of casein plus methionine in lactating ewes fed fresh pasture

Barry¹

1980

New Zealand Journal of Agricultural Research

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Twin-bearing Romney ewes were fed fresh pasture of 80% organic matter digestibility (11.4 MJ ME per kg OM) and 3.5% N ad libitum for 6 weeks during early lactation. Eight of the 18 ewes were given a daily abomasal infusion of 95 g sodium caseinate and 2 g I-methionine. Voluntary pasture OM intake did not significantly differ between control and infused ewes. The infusions had no effect on milk secretion at peak lactation (week I), but the decline in net rates of protein and fat secretion as lactation progressed was less for infused than for control ewes. Wool production rates were low, and were unaffected by the infusion treatment. The quantity of amino acid N estimated to have been absorbed from the small intestine was respectively 85% and 110% of that required to sustain the levels of milk and wool production that were actually recorded in control and infused ewes. The absence of a difference in milk production between the two groups of ewes at peak lactation may have been due to greater mobilisation of body protein reserves by the control ewes. The higher plasma concentration of growth hormone observed in the infused ewes was probably implicated in their improved lactation persistency.

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“…However, in a recent review, Beever and Siddons (1986) estimated an apparent loss of N between mouth and duodenum, which may account for up to 30% of ingested N. Cammell et al (1983) estimated microbial N flows at over 75% of nonammonia-N flow for ryegrass and clover diets, of which 60 (MacRae and Ulyatt, 1974) to 80% (Salter and Smith, 1977;Storm et al, 1983) would be available. From the estimates of N loss, energetic limits to microbial protein synthesis and limited true digestibility of microbial N, it is plausible that only a fraction of the ingested forage N is actually used by the animal.…”

Section: Introductionmentioning

confidence: 99%

Escape Protein Supplementation of Yearling Steers Grazing Smooth Brome Pastures

Anderson

Klopfenstein

Wilkerson

1988

Journal of Animal Science

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Two grazing trials utilizing individually supplemented yearling steers were conducted to study the effect of supplemental escape protein on steer performance during the active growth periods, spring and fall, of smooth brome (Bromus inermis). Graded levels (0, . 11, .23 and .34 kg.head-l.d-l) of an equal-proteinbasis mixture of bloodmeal and corn gluten meal were offered daily, replacing corn starch, which was used as the negative control. All steers received 582 g supplemental dry matter per day. Supplementation with escape protein improved daily performance in both spring (P<.01) and fall (P<.02). Analysis of pooled data from both trials indicated a linear (P<.01) and quadratic (P<.05) increase in steer performance with increasing level of escape protein in the diet. Analysis of grass samples collected throughout and composited over each trial demonstrated that grass protein was highly degraded in the rumen. Using a modified dacron bag technique, 12-h degradability was found to be 80 to 90% of the potentially digestible protein fraction. Rates of protein degradability were 14 and 11.7%/h. Assuming 5%/h rate of passage, escape protein was calculated to be 9.2 and 13.1% of total protein. As a result of the significant growth response observed above that of the energy-supplemented controls and the high ruminat protein degradabilities of the grass observed in the laboratory, it was concluded that growing ruminants grazing actively growing smooth brome pastures were deficient in metabolizable protein.

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Quantitative digestion of fresh herbage by sheep: II. The sites of digestion of some nitrogenous constituents

Cited by 130 publications

References 13 publications

The efficiency of energy utilization in growing cattle consuming fresh perennial ryegrass (Lolium perenne cv. Melle) or white clover (Trifolium repens cv. Blanca)

The efficiency of energy utilization in growing cattle consuming fresh perennial ryegrass (Lolium perenne cv. Melle) or white clover (Trifolium repens cv. Blanca)

Responses to abomasal infusions of casein plus methionine in lactating ewes fed fresh pasture

Escape Protein Supplementation of Yearling Steers Grazing Smooth Brome Pastures

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