In Vitro Effect of pH Variations on Rumen Fermentation, and In Vivo Effects of Buffers in Lambs before and after Adaptation to High Concentrate Diets

Abstract

An in vitro wheat fermentation study (Exp. 1) was conducted to investigate the effect of pH (pH 7, 6, 5 and 4) on rumen lactate and VFA production. In another study (Exp. 2), lambs were fed high concentrate diets containing either no additions (control), 2% sodium bentonite, 2% limestone, 2% NaHCO3 or 10% alfalfa hay. The effect of these diets was determined on ruminal and systemic measurements before and after dietary adaptation. Effect of the control, bentonite, limestone and NaHCO3 treatments on nutrient digestibilities and mineral retentions after adaptation were also determined. Lactate production in the rumen fluid incubated at pH 7 or 6 was negligible. Reducing incubation pH from 6 to 5 resulted in accumulation of both total and L(+)-lactate, but further reduction to pH 4 did not result in an additional increase in lactate production. Variations in incubation pH or time did not affect the ratio of D to L isomers. Lowering the incubation pH to below 6 reduced total VFA production and increased the acetate to propionate ratio. In Exp. 2, the feeding of buffers or alfalfa hay was effective in maintaining a more normal feed intake and ruminal pH, and reduced ruminal lactate. Blood measurements were not affected by dietary treatment. When animals were adapted to the experimental diets, the dietary buffers did not influence rumen and blood measurements. Lambs fed 2% NaHCO3 digested more (P less than .05) organic matter, crude protein, N-free extract and starch, and 2% limestone increased (P less than .05) fiber digestibility. Dietary buffers tended to increase fecal pH and reduce fecal starch Magnesium retention with 2% bentonite, Ca retention with 2% limestone and Na and Mg retention with NaHCO3 were all increased (P less than .05).

Total mixed ration pellets for light fattening lambs: effects on animal health

“…As a consequence, feed requires more time to be digested, staying longer in the digestive tract (especially in the rumen) and filling it. In fact, the fermentation pattern is different depending upon the diet, as is rumen pH, which is increased in response to forage intake (Carro et al, 2000), especially if it is alfalfa (Ha et al, 1983), as observed in our study. In the case of alfalfa-fed lambs, its intrinsic buffering capacity (Giger-Reverdin et al, 2002), together with its coarse structural fibre that stimulates ruminative chewing and salivation, increases rumen buffering capacity (Mirzaei-Aghsaghali et al, 2008).…”

Use of calcareous algae and monensin in Nellore cattle subjected to an abrupt change in diet

“…There are few studies where the effects of CA on blood characteristics have been evaluated. However, HA et al (1983), when assessing buffering effects in lambs fed with a high concentrate diet, reported no effect of treatments on blood lactic acid concentration. WHEELER et al (1981) also reported no difference in blood pH or bicarbonate when evaluating the effect of calcium levels and baking soda in high concentrate diets for beef cattle.…”

Effect of dehydrated lucerne on lamb performance and protein and energy deposition in the body

“…Feeding high-concentrate or all-concentrate, low fibre, pelleted diets decreases salivary production and rumen pH, alters microbial fermentation and, therefore, dietary buffers are necessary as agents preventing acidic conditions (Linda and Wohlt, 1985;Stroud et al, 1985). Ha et al (1983), Stroud et al (1985) and Urbaniak and Przybecki (1994) indicate that dehydrated lucerne (DL) can be used in diets for growing ruminants both as a buffering agent and a protein source with a limited level of ruminal degradation which increases the pH of the rumen liquid, the acetic to propionic acid ratio and the amino acid flow through the duodendum. DL is a feed rich in lysine, calcium, phosphorus and crude fibre and also has been used to replace concentrate in rations for lactating dairy cows (Christensen and Cochran, 1983;Kirkpatrick et al, 1984;Price et al, 1988).…”