Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.593132
Title: Method for improving the intake and nutritive value of poor-quality roughages
Author: Mira, Joaquim Jose Franco
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1981
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Abstract:
A series of experiments was conducted to investigate the value of cereals or high-quality forages as supplements to poor quality roughages. A review of the literature suggested that work was required with cattle to examine the effects on intake and live weight gain of offering long straw and straw that had been subjected to mechanical processing. The project also set out to assess the relative value of various chemicals for treating long straw. 1. Two experiments were made with growing lambs offered hay containing 71.5 g CP/kg DM. These showed that replacement rates were similar with rolled barley or high quality dried grass. The physical form of the dried grass (i.e. chopped or pelleted) was important in determining the amount of hay eaten. High quality forages are valuable supplements to use with poor quality forages because they are good sources of both energy and protein. The extent to which they are used will depend largely on their costs of drying. Where cereals were offered as a supplement to hay, detailed studies on digestion in the rumen suggested that the rate of disappearance of roughage from dacron bags suspended in the rumen was reduced as the amount of cereals offered was increased. They further showed that the retention time of solid particles in the rumen as measured from 103Ru-ph excretion, was increased as the amount of cereals offered was increased. In the intact animal both these effects would contribute towards the well known increase in replacement rate associated with increasing rates of cereal supplementation. 2. An intake and growth experiment was made with growing steers offered long or shredded barley straw together with three different amounts of rolled barley offered separately from the straw. The intake of long straw was greater than that of shredded straw. There were no differences in daily gain or feed efficiency between steers offered the two forms of straw. These experiments were supported by measurements of digestibility and retention time made using three steers prepared with rumen fistulae. Digestibility was determined by total faeces collection and retention times using 103Ru-ph and 51Cr-EDTA. They showed that digestibility was somewhat higher with long than medium or fine chopped straw. The physical form of straw did not affect the retention time of either the particulate or liquid phase of digesta in the rumen. The results of these trials suggested therefore that mechanical processing of barley straw was not a prerequisite for high straw intakes and adequate daily gains in beef cattle. 3. Experiments were made with growing lambs and steers offered barley straw treated with urea or after exposure to anhydrous ammonia. The importance of an adequate supply of sulphur was deduced from two experiments that involved supplementation with both urea and ammonium sulphate. When ammonia treated straw was used animal performance was related to the capture of ammonia by the straw. A high retention of the injected ammonia led to a high straw intake and a good growth rate. These points highlight the need for a good seal of the plastic sheet round the straw stack before the ammonia is injected. The results of the growth experiments made with steers showed that straw intake and daily gain were higher with straw after treatment with ammonia than with urea. The difference between the two types of nitrogen supplementation was most marked when the two amounts of barley were offered. The results obtained with steers offered only rolled barley suggested that in the short term urea does not always increase straw intake. These experiments prepare the way for developing systems for over-wintering stock with a view to obtaining good gains at pasture the following summer. These systems need not bear the high feed cost associated with some previous developments using cereal straws.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.593132  DOI: Not available
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