Rumen Acid Production from Dairy Feeds. 1. Effects on Feed Intake and Milk Production of Dairy Cows Offered Grass or Corn Silages

Abstract

Earlier studies developed a new approach to feed evaluation, measuring the net acid load that develops during rumen fermentation. Two concentrates were formulated to be isoenergetic and isonitrogenous, with extremes of rumen acid load. A third treatment comprised a 50:50 mixture of these concentrates. These concentrates were evaluated along with ryegrass silage and corn silage. The feeds were evaluated in a continuous culture system adapted to deliver and record the quantities of acid or alkali needed to maintain a constant pH (6.2 to 6.3). This study confirmed the anticipated ranking of concentrates for rumen acid load, as well as the highly acidogenic nature of corn silage. The concentrates were formulated to balance corn silage and were offered to early-lactation Holstein-Friesian cows at 50% of dry matter intake, with either ryegrass silage or corn silage. Feed intake was lower for animals offered corn silage-based diets (17.4 vs. 22.2 kg of dry matter/d). Increasing concentrate acid load led to a large decline in dry matter intake for corn silage, although not for grass silage. Feed intake effects were reflected in significant effects on yield of milk (31.0, 29.9, and 26.9 kg/d for low-, medium-, and high-acid load concentrates, respectively) and milk solids. Milk protein concentration was unaffected by concentrate type with corn silage diets but tended to be higher when high acid load concentrates were fed with grass silage. This may reflect the effect of the high starch concentrate rectifying a shortage of glucogenic precursors or microbial protein with the grass silage-based diet.

The effect of dent versus flint maize genotype on site and the extent of starch and protein digestion, ruminal fermentation and microbial protein synthesis in the rumen of sheep

“…The data were not consistent with the findings of Martin et al [24] who observed no difference in ruminal pH value of steers given either flint or dent corn. In diets containing large amounts of maize silage, animal performance may be adversely affected by subacute rumen acidosis [10]. The possibility of manipulating rumen pH value by choosing an adequate genotype, is therefore of great practical importance.…”

Effects of Dietary Potential Acid Production Value on Productivity in Dairy Cows

“…A negative correlation between dietary PAPV and milk protein was noticed, although the relation was not significant in the present study. Dewhurst et al (2001) reported that milk protein concentration was not influenced by concentrate type when using corn silage as a roughage source but tended to be higher when high acid load concentrates were fed with grass silage. However, the relationship was not sound, which indicates that milk protein did not fluctuate to a great extent based on diet.…”

“…This is somewhat different from previous results. For instance, increasing concentrate acidogenicity was negatively related to dry matter intake (Wadhwa et al, 2001b) and milk yield (Dewhurst et al, 2001), with variable effects on milk composition. The PAPV of TMR used in the experimental farms ranged from 5 to 15; therefore, the PAPV was not high enough to yield a negative impact on production traits.…”

“…Diets should be formulated to maintain optimal ruminal pH, and ruminal pH should have minimal variation due to feeding management. Previous studies suggested that ruminal pH correlates closely with ruminal motility (Ash, 1959), microbial yield (Oliveira et al, 1997), methane production (Lee et al, 2003), dry matter intake (Dewhurst et al, 2001), milk yield (Wadhwa et al, 2001b) and fiber digestion (Smith et al, 1973; Fondevilla et al, 1994). Low ruminal pH has direct and negative effects on energy intake and absorption of protein, which is a primary factor limiting production of high producing dairy cows.…”

Investigation of Dietary Lysophospholipid (LipidolTM) to Improve Nutrients Availability of Diet with In Vitro Rumen Microbial Fermentation Test

“…In addition, rumen pH is one of the most critical determinants for rumen function as cellulolytic bacteria fail to grow below pH 6.0. While, early studies have reported that low rumen pH has negative effects on appetite (Shinozaki, 1959), microbial yield (Oliveira et al, 1997;Russell and Dombrowski, 1980), methane production (Lee et al, 2003), dry matter intake (Dewhurst et al, 2001), milk yield (Wanapat et al, 2009) and fiber digestion (Smith et al, 1973;Stewart, 1977;Terry et al, 1969).…”