Effect of Calcium Supplementation on Ruminal Soluble Calcium Concentration and Ruminal Fermentation.

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Title: Effect of Calcium Supplementation on Ruminal Soluble Calcium Concentration and Ruminal Fermentation.
Author: Baird, Emily Jean
Advisors: Dr. Jerry Spears, Committee Chair
Dr. Vivek Fellner, Committee Member
Dr. Jeannette Moore, Committee Member
Abstract: Two experiments were conducted to determine the effect of Ca source and concentration on ruminal soluble Ca concentration and microbial fermentation. In the first study, experimental diets (14 g DM/d) were added to continuous flow culture fermentors in two equal portions at 0800 and 1700-h. Treatments consisted of control diet (0.18% Ca) or the control supplemented with 0.60% Ca from either 1) CaCO3, 2) Ca propionate-prilled (CaP, Nutrocal®) or 3) Ca propionate-powder. Following a 2-d stabilization period, fermentors were sampled over a 4-d collection period. Each treatment was replicated five times. Calcium supplementation of the control diet increased ruminal soluble Ca concentrations. Ruminal soluble Ca concentrations were higher in cultures receiving Ca propionate compared to CaCO3. Ruminal pH was lower in Ca supplemented diets compared to control, and CaCO3 supplemented cultures yielded higher pH values than Ca propionate treatments. Digestibility of NDF was higher in fermentors receiving prilled Ca propionate compared to those supplemented with powdered Ca propionate. Total VFA production in ruminal cultures was increased by supplemental Ca. In response to Ca source, total VFA production was higher for Ca propionate than CaCO3 and Ca propionate-prilled compared to Ca propionate-powder treatments. Propionate production and molar proportion were higher in Ca propionate than control or CaCO3 treatments. Butyrate production was higher for Ca propionate-prilled and CaCO3 treatments compared to control and Ca propionate-powder treatments. Molar proportion of butyrate was higher for CaCO3 than the other treatments. Production and molar proportion of isovalerate was lower for Ca propionate-powder compared to other treatments. Calcium supplementation did not affect C16:0, C18:0, C18:2, CLA cis9, tran11 or CLA trans10, cis12 isomers. However, the proportion of C18:1 trans isomers as well as the total proportion of C18:1 isomers increased as a result of supplementing Ca. Calcium carbonate increased C18:0 and proportions of C18:1 cis, and reduced C18:2 compared to Ca propionate addition. The second experiment utilized sixteen Angus steers initially averaging 274 kg (trial 1) or 252 kg (trial 2). Animals were divided by weight and randomly allotted to three treatments. Eight steers were randomly assigned to one of the following treatments in each of two trials: 1) control (no supplemental Ca), 2) CaCO3 and 3) Ca propionate (prilled). Each steer was supplemented with 1.36 kg of a corn-corn gluten feed supplement per day. The supplement provided 14.8 g of Ca per day for steers in treatments two and three. Chopped orchardgrass hay containing 0.2% Ca was also fed to all steers based on what each animal would consume in a 24-h period. Following a 14-d adjustment period, steers were placed in metabolism crates. Steers were acclimated to the metabolism crates for 5-d followed by a collection period of 5-d in order to obtain a total collection of urine and feces. Dry matter intake and digestibility during the digestion period were both similar across treatments. NDF intake and digestibility were also not affected by Ca level or source. Ca supplementation increased ruminal soluble Ca concentrations; however, concentrations were much higher in steers supplemented with Ca propionate compared to CaCO3. Plasma Ca concentrations were not affected by Ca supplementation. Total VFA concentrations were not affected by Ca level or source. However, the addition of Ca significantly decreased molar percentages of acetate. In fact, the proportion of acetate was lower with supplemented Ca propionate compared with CaCO3. The addition of Ca significantly increased the molar percentages of propionate. Supplemental Ca propionate resulted in much greater proportions of propionate compared to CaCO3 addition. Steers supplemented with Ca propionate had a lower acetate:propionate ratio than those supplemented with CaCO3. Molar proportions of butyrate, valerate, and the isoacids, isobutyrate and isovalerate, were not affected by the addition of Ca. These results indicate the importance of considering the difference in solubility of Ca found in feedstuffs and supplemental Ca sources. In the fermentor study, both Ca level and source affected ruminal soluble Ca concentrations and fermentation. Soluble Ca concentrations were greater in cultures supplemented with Ca propionate compared with those supplemented with CaCO3. This may be due to the difference in solubility of the supplemental Ca sources. The amount of ruminal soluble Ca will depend on the solubility present in feedstuffs as well as supplemental sources of Ca. However, increased ruminal soluble Ca concentrations in the second experiment did not affect ruminal fermentation. The lack of a significant increase in digestion as a result of Ca supplementation may be explained in that adequate amounts of soluble Ca may have existed in the supplement and orchardgrass hay to meet the microbes' Ca requirement. This suggests that the Ca present in the hay was fairly soluble in the ruminal environment and contributed to ruminal soluble Ca concentrations. These results indicate that dietary Ca source affects ruminal soluble Ca concentrations and ruminal fermentation.
Date: 2006-03-07
Degree: MS
Discipline: Animal Science
URI: http://www.lib.ncsu.edu/resolver/1840.16/386

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