Influence of feeding and social behaviors and the use of sodium bicarbonate on ruminal pH of beef cattle fed high concentrate diets

by González, Luciano Adrián

Abstract (Summary)
The objective of the present thesis was to study the effects of some behavioral factors, and the use of sodium bicarbonate, on the digestion processes affecting ruminal function of beef cattle fed concentrate and straw ad libitum. In the first experiment, four ruminally fistulated Holstein heifers were used in a 4 x 4 Latin square design to determine the effect of increasing levels of sodium bicarbonate (0, 1.25, 2.50 and 5 %, on concentrate DM basis) on intake, water consumption, ruminal fermentation, and chewing and feed intake behaviors. Concentrate and barley straw were fed once daily at 0830 and ad libitum. Concentrate decreased and straw DMI increased linearly with buffer level. Water consumption increased linearly when expressed in L/kg of DMI but not in L/d. Daily mean and lowest ruminal pH were not affected by treatments. However, ruminal fluid pH increased linearly at 2 and 4 h after feeding and the number of hours in which ruminal pH was below 5.8 was greatest when no buffer was added. Daily average molar proportion of propionate decreased linearly but acetate, butyrate, and branched-chain VFA increased linearly as the level of bicarbonate increased. Meal frequency and eating rate decreased linearly. Time spent eating per unit of DMI increased linearly with buffer level. In the second experiment, 72 Friesian calves were distributed in a factorial design with 3 treatments and 3 blocks of similar fasted BW to study the effect of increasing competition on performance, behavior, and welfare indicators throughout the 4 wk after arrival. Treatments consisted of increasing levels of social competition with the use of 1, 2 or 4 concentrate feeding places/pen (8 calves/pen). Concentrate and straw were fed ad libitum at 0830 and in individual feeders. Increasing competition resulted in a linear decrease of concentrate DMI and ADG during wk 1 after arrival but the response was quadratic in wk 3 and 4, being lowest at the greatest competition. Straw intake and the within-pen SD of ADG tended to increase linearly with competition during the 4-wk receiving period. Increasing competition at the concentrate feeders reduced lying time, increased standing time, and changed the diurnal feeding pattern (concentrate eating time decreased but straw eating time increased during peak feeding times). Increasing social competition at the concentrate feeders accentuated the effects of dominance rank on ADG, with their relationship being negative at wk 1 but positive at wk 3. The same 72 heifers with the same experimental setup were used to study the effect of increasing competition on performance, behavior, welfare, and ruminal fermentation of feedlot heifers. After the 4-wk adaptation period, DMI and ADG were measured, and blood and rumen samples were taken during 6, 28-d experimental periods. Fecal corticosterone and behavior were measured at periods 1, 3 and 6. Concentrate intake decreased linearly with competition but final BW, ADG, and G:F ratio were not affected by treatments. The proportion of abscessed livers responded quadratically with high proportion at the greatest competition. Concentrate eating time decreased, and eating rate, standing time, and aggressions increased linearly with competition for concentrate. The pen-average fecal corticosterone was not affected by treatments but that of dominants responded quadratically, being greatest with the greatest competition. Serum haptoglobin concentration increased linearly with competition, particularly within the most subordinate heifers. Increased competition reduced ruminal pH only in periods 1 and 2 but tended to increase the proportion of heifers with ruminal pH below 5.6 and increased ruminal lactate. The present thesis shows that feeding behavior in beef cattle allows better understand ruminal function and to assess welfare as well.
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Bibliographical Information:

Advisor:Ferret Quesada, Alfred; Manteca i Vilanova, Xavier

School:Universitat Autónoma de Barcelona

School Location:Spain

Source Type:Master's Thesis

Keywords:458 departament de ciències animals i dels aliments


Date of Publication:11/30/2007

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