Individual feed intake by ruminants in group feeding situations

McEleney, Elizabeth (1985) Individual feed intake by ruminants in group feeding situations. PhD thesis, University of Glasgow.

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The main objectives of this thesis were to assess the variation in individual feed intake by ruminant livestock in group feeding situations, as influenced by animal (e. g. , disease, rank-order position), feed (e. g. , physical form, quantity allocated) and management (e. g. , method of feed presentation) factors. Determination of individual feed intake in group feeding situations by complete faecal collection was not usually practicable and therefore in Section 1 an indigestible faecal marker technique for assessment of individual feed intake was successfully developed and evaluated. In Section 2 calibration equations of the form y = c + mx (where y = feed DM intake and x = faecal chromium concentrations from grab samples) were computed to facilitate the determination of individual feed intake of ewes in early lactation and to assess the influence of method of feed presentation on the variation in feed intake. The calibration equations successfully predicted the individual feed intake of the ewes and the method of feed presentation (either from troughs, behind a feed barrier or from a feedring) did not appear to markedly influence the uniformity of individual feed intake in the group of ewes. In Section 3 the influence of the physical form of the diet (a bulky complete diet compared with a conventional hay and concentrates diet) and the quantity allocated on the variation in individual feed intake of ewes in late pregnancy was investigated using complete faecal collections. Plasma ketone bodies and non-esterified fatty acids were also determined to assess the ME status of the ewes. The bulky complete diet promoted a marginally more uniform intake of ME compared with the more conventional hay and concentrates diet. An increase in the quantity of feed allocated to the ewes did not markedly alter the variation in intake in the group and it was concluded that the increment was not sufficiently large to do so. In Section 4 aspects of palatability of pelleted compounds were investigated in dry non-pregnant ewes and in ewes in late pregnancy. Incorporation of ingredients into the pelleted compound feed at or beyond their normal inclusion levels promoted greater uniformity of individual feed intake in the group of dry, non-pregnant ewes, compared with allocation of a more acceptable compound feed which was readily consumed by a similar group of ewes. This effect was not repeated with similar ewes in late pregnancy possibly due to increased physiological demand which may have encouraged ready consumption of compound feed, irrespective of ingredient inclusion. The influence of physical form, quantity allocated, method of presentation and frequency of feeding of compound feeds on the variation in individual compound feed intake by cattle was investigated in Section 5. The physical form of the compound feed on offer was particularly noted to influence the variation in compound feed intake in the group. The possible influence of ostertagiasis on the variation in the intake of hay (indoors) and compound feed (at grass) was investigated in steers. The group of steers which had been most deleteriously afflicted by ostertagiasis demonstrated greater variation in individual intake than the control groups. In Section 6 the individual intake of grass silage by dairy cows was measured under different methods of access (i.e., self-feed versus easy-feed). Easy-feed access was observed to encourage greater uniformity of silage intake in the herds investigated, particularly between the cows and first-calving heifers. In Section 7 the individual intake of pelleted compound feeds by the dairy herds (Section 6) were determined. First-calving heifers were observed to consume less than the cows within the herd. A comparison was also undertaken between the variation in individual intake of a novel loose compound meal and a pelleted compound feed by dairy cows. Possible influences on milk yield and composition were also investigated. When the novel loose meal was offered the first-calving heifers consumed significantly less compound dry matter than the cows. This was not repeated when the pelleted compound feed was offered. There were no marked influences on milk yield and composition. It was concluded that variation in the individual intake of group fed roughages tended to be less than that of compound feeds. Nevertheless accurate individual allocation of compound feeds, particularly in the dairy herd, may not be worthwhile where the roughage component of the diet is group fed.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Animal sciences
Date of Award: 1985
Depositing User: Enlighten Team
Unique ID: glathesis:1985-76549
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 14:10
Last Modified: 19 Nov 2019 14:10

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