The effect of previous body condition on appetite and associated insulin profiles in sheep

Abstract

The effect of previous level of body condition on appetite was studied in 47 housed Scottish Blackface ewes, which had been either thin (L: mean condition score 2-15, s.e. 0-030; no. = 24) or fat (H: mean condition score 3-15, s.e. 0-056; no. = 23) 8 weeks before the start of the experiment. The mean daily voluntary food intake (VFI) of a dried grass pellet diet was higher for the L than for the H ewes (2176 v. 1727 g dry matter per day; P < 0-001) during the first 6 weeks of the experiment (period 1). Over this time, live weights increased from 60-5 or 69-9 (s.e.d. 1-68) to 68-4 or 75-6 (s.e.d. 1-94) and condition scores increased from 2-84 or 3-16 (s.e.d. 0-057) to 3-13 or 3-38 (s.e.d. 0-071) for the L and H ewes respectively. At the end of the 6-week period, plasma insulin concentrations were measured in 10 ewes from each treatment (mean condition scores 3-15 (L) and 3-27 (H) (s.e.d. 0-091)) when fed both ad libitum and at a fixed level of 1200 g/day for consecutive 11-day periods (period 2). Mean VFI was higher for the L than for the H ewes (2191 v. 1661 g dry matter per day; P < 0-05) over the period of ad libitum feeding. There was no effect of feeding level (ad libitum v. 1200 g/day) on mean plasma insulin concentrations, but the mean basal plasma insulin concentration was higher in the H than in the L ewes (43-0 v. 29-0 mil per 1; P < 0-05). Fifteen minutes after the ingestion of a single 400 g meal, the plasma insulin concentration in the H ewes was higher than the mean prefeeding value (63-3 v. 41-7 mil per I; P<0-05) but there was no corresponding increase in the L ewes. The plasma insulin concentration 15 min after the intravenous administration of a single dose of 0-25 U per kg live weight of insulin ivas higher in the H than in the L ewes (1723 v. 1031 mil per 1; P < 0-01) but there were no differences between treatments in plasma glucose concentrations following insulin administration.It zvas concluded that previous body condition can affect contemporary VFI and this effect may be mediated by plasma insulin concentrations providing a long-term feedback signal to the brain.

Review of sheep body condition score in relation to production characteristics

“…The data of Sibbald & Rhind (1997) indicate greater BCS is associated with reduced intake, which does not simply suggest they are not hungry. The results of Caldeira et al (2007) propose that metabolic imbalance can occur with a BCS below 2.0 or above 4.0, which may be suggestive of reduced health outcomes for ewes in these ranges.…”

The relationship between forage cell wall content and voluntary food intake in mammalian herbivores

“…One important aspect of the organismal strategy is the body condition of the animal at the beginning of the decline in diet quality. Studies in sheep (Foot 1972, Sibbald & Kerr 1994, Sibbald 1997, Sibbald & Rhind 1997, Tolkamp et al. 2006) and cattle (Bines et al.…”

The response to dietary threonine in laying-type pullets during growth

“…The theory of food intake of Emmans (1981Emmans ( , 1987 predicts that birds will get fat when offered a feed with limiting protein or an amino acid because they will overconsume energy in an attempt to consume sufficient of the limiting nutrient in the feed in an endeavour to grow at their potential. This theory has been confirmed many times (Foot, 1972;Emmans, 1981;Gous et al, 1990Gous et al, , 2012Sibbald and Rhind, 1997;Whittemore, 1998). The extent to which energy can be overconsumed depends on the amount of lipid that can be stored in the body: if the genotype is such that a large amount of lipid can be stored, then the bird will be capable of consuming relatively more of an imbalanced feed than one whose ability to fatten is limited genetically.…”

“…It is also necessary to know the extent to which the given strain can deposit lipid as a means of overcoming a nutrient deficiency: birds and animals overconsume energy in an attempt to consume sufficient of the limiting nutrient in the feed (Foot, 1972;Emmans, 1981;Sibbald and Rhind, 1997;Whittemore, 1998;Gous et al, 2012), but this overconsumption is limited by the extent to which the genotype can deposit lipid, i.e., lean genotypes are unable to compensate to the same extent as fat genotypes for a marginal nutrient deficiency, and therefore, the amino acid-to-energy ratio in lean genotypes is more critical in such strains. In addition, to calculate a bird's daily nutrient requirements, it is necessary to know whether the efficiency of utilisation of amino acids for protein growth changes during growth.…”