Amino Acid and Energy Metabolism in the Peripheral Tissues of Ruminants

Harris, P. M.; Lobley, G. E.

doi:10.1016/b978-0-12-702290-1.50017-5

Cited by 14 publications

(21 citation statements)

References 95 publications

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“…Huston, 1980;Ash and Norton, 1984;Hobson, Grobbelaar, Wentzel and Koen, 1986;Calhoun, Lupton, Kuhlmann and Baldwin, 1988) and indicates that the energy supply for hair follicle activity and protein synthesis was not limiting fibre growth. It differs from the effect produced in sheep wool by the increase in dietary energy to 20 X maintenance as cited by Harris and Lobley (1991). In contrast, fibre yield and diameter were highly sensitive to dietary protein supply.…”

Section: Discussioncontrasting

confidence: 63%

“…acids (Ryder, 1973). Harris and Lobley (1991) in their Knowledge of how absorbed nutrients are recent review have summarized the importance of partitioned between mohair fibre and non-mohair wool growth in the nitrogen and energy metabolism components is of particular interest since both fibre of sheep. In particular they indicated the positive and meat products will become increasingly response to increases in energy intake above 0-5 X available as goat numbers increase.…”

Section: Introductionmentioning

confidence: 99%

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The effect of changes in dietary protein and energy on growth, body composition and mohair fibre characteristics of British Angora goats

1992

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Twenty-four castrated male British Angora goats of Australasian origin aged 11 months and weighing 23-5 kg live weight were studied in a 112-day experiment. They were allocated in a 2 X 2 factorial design to receive diets containing, per kg dry matter, concentrations of estimated metabolizable energy (ME) of 10-2 M] (LE) or 11-9 MJ (HE) and crude protein concentrations of 108 g (LP) or 180 g (HP). The HE diets were offered to provide a dry-matter intake of 30 g/kg live weight and the LE diets to provide 0-85 of the ME intake of HE diets. In comparison with LE diets, the HE diets, on average, increased live-weight gain, food conversion efficiency, carcass weight, killing-out proportion, empty body weight, cross-sectional area of m. longissimus dorsi and fat thickness over m. serratus dorsalis and weights in the carcass for dissected lean tissue, crude protein (N X 6-25) and dissected and chemically extracted fat. Weights of shoulder, hind barrel, and best-end joints and their weights of dissected lean and fat were increased on HE diets. No consistent effects due to dietary energy were observed for yield or diameter of mohair fibres. The greater intake of dietary protein resulted, on average, in increased values for live-weight gain, efficiency of food conversion, carcass weight, weight of dissected carcass lean tissue and crude protein, killing-out proportion and crosssectional area of m. longissimus dorsi. The greater intake of dietary protein increased significantly both yield and diameter of mohair fibre. Significant interactions between protein and energy for empty body weight, carcass weight and carcass fat indicated that increasing dietary protein intake had a greater positive effect on the low than on the high energy diets. Similarly, increasing the dietary energy consumption on the LP diets produced a greater positive effect than that recorded on the HP diets. The results indicated that growth and lean tissue deposition were affected by both protein and energy intakes but that mohair fibre characteristics were affected consistently only by protein nutrition.

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Section: Discussioncontrasting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

The effect of changes in dietary protein and energy on growth, body composition and mohair fibre characteristics of British Angora goats

1992

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“…Wool protein synthesis makes up a variable proportion of total skin protein synthesis but, in a maintenance or sub-maintenance state, wool protein synthesis domi¬ nates skin nitrogen metabolism while cysteine makes up 9-10% of wool protein but only 2-3% of skin protein amino acids (Harris & Lobley, 1991). In contrast, phenylalanine content is more comparable in these proteins, comprising 4-5% of wool protein and 3% of skin protein, hence a shift in proportion of wool protein synthesized will have a smaller effect on phenylalanine utilization than on cysteine utilization.…”

Section: Discussionmentioning

confidence: 99%

Direct infusion of a variant of insulin-like growth factor-I into the skin of sheep and effects on local blood flow, amino acid utilization and cell replication

Harris¹,

McBride²,

Gurnsey³

et al. 1993

Journal of Endocrinology

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In vivo effects of local infusion of a variant of insulin-like growth factor-I (IGF-I), long-R3-IGF-I, into the skin were investigated using six conscious sheep with food available ad libitum. An artery and vein on the abdominal flank of each animal, as well as the saphenous artery, were catheterized so that infusion of isotopically labelled amino acids, with or without IGF-I, could be used to determine amino acid uptake by arteriovenous difference in combination with blood flow determined by dye dilution. Measurements were made on each animal prior to IGF-I infusion, at hourly intervals for the 4 h of IGF-I infusion into the skin artery, then 2 and 4 h after IGF-I infusion ceased. Numbers of cells replicating in the bulbs of wool follicles in the IGF-I-infused area and in the skin on the contralateral side of each animal were measured after labelling with 5-bromo-2'-deoxyuridine. IGF-I caused a significant increase in the skin blood flow (P < 0.05), utilization of oxygen (P < 0.05), uptake of cysteine (P < 0.05) and phenylalanine (P < 0.001), and the rate of utilization of cysteine (P < 0.05) for protein synthesis. IGF-I increased amino acid uptake regardless of whether the skin was in negative or positive amino acid balance prior to infusion. During the recovery period amino acid utilization by skin returned towards preinfusion levels. No effects of IGF-I were found on replicating cell numbers in the bulbs of wool follicles.

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“…This amino acid may also have wider implications for herbivores. L-Met is considered to be one of the most limiting amino acids for protein synthesis in growing ruminants, lactating dairy cows, and wool-producing sheep (Harris and Lobley, 1991;Schingoethe, 1996) and is often supplemented to decrease protein and amino acid degradation in the rumen (Sü dekum et al, 2004). We do not know yet if high-sugar cultivars in general accumulate more L-Met, but if this were the case, reported increases in protein availability and milk and meat production, and decreases of N excretion in urine by high-sugar grass-grazing animals (for review, see Edwards et al, 2008 [on high-sugar grasses and their advantages for pasture-fed animals]) might not only be caused by higher sugar levels, but rather by a combination of increased sugar and L-Met levels.…”

Section: Effects Of High-sugar Cultivarmentioning

confidence: 99%

Metabolic Profiles ofLolium perenneAre Differentially Affected by Nitrogen Supply, Carbohydrate Content, and Fungal Endophyte Infection

et al. 2008

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Lolium perenne cultivars differing in their capacity to accumulate water soluble carbohydrates (WSCs) were infected with three strains of fungal Neotyphodium lolii endophytes or left uninfected. The endophyte strains differed in their alkaloid profiles. Plants were grown at two different levels of nitrogen (N) supply in a controlled environment. Metabolic profiles of blades were analyzed using a variety of analytical methods. A total of 66 response variables were subjected to a principle components analysis and factor rotation. The first three rotated factors (46% of the total variance) were subsequently analyzed by analysis of variance. At high N supply nitrogenous compounds, organic acids and lipids were increased; WSCs, chlorogenic acid (CGA), and fibers were decreased. The high-sugar cultivar 'AberDove' had reduced levels of nitrate, most minor amino acids, sulfur, and fibers compared to the control cultivar 'Fennema', whereas WSCs, CGA, and methionine were increased. In plants infected with endophytes, nitrate, several amino acids, and, magnesium were decreased; WSCs, lipids, some organic acids, and CGA were increased. Regrowth of blades was stimulated at high N, and there was a significant endophyte 3 cultivar interaction on regrowth. Mannitol, a fungal specific sugar alcohol, was significantly correlated with fungal biomass. Our findings suggest that effects of endophytes on metabolic profiles of L. perenne can be considerable, depending on host plant characteristics and nutrient supply, and we propose that a shift in carbon/N ratios and in secondary metabolite production as seen in our study is likely to have impacts on herbivore responses.

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Amino Acid and Energy Metabolism in the Peripheral Tissues of Ruminants

Cited by 14 publications

References 95 publications

The effect of changes in dietary protein and energy on growth, body composition and mohair fibre characteristics of British Angora goats

The effect of changes in dietary protein and energy on growth, body composition and mohair fibre characteristics of British Angora goats

Direct infusion of a variant of insulin-like growth factor-I into the skin of sheep and effects on local blood flow, amino acid utilization and cell replication

Metabolic Profiles ofLolium perenneAre Differentially Affected by Nitrogen Supply, Carbohydrate Content, and Fungal Endophyte Infection

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