Effect of grain sorghum hybrid on in vitro rate of starch disappearance and finishing performance of ruminants

Effects of grain level on lamb performance, ruminal metabolism and leptin mRNA expression in perirenal adipose tissue

The effects of four different grain composition diets of finishing lambs on lamb performance, dry matter (DM) digestibility, rumen fermentation and leptin mRNA expression were evaluated. Thirty-two Pelibuey lambs (25.35 ± 4.73 kg bodyweight) were used in a completely randomised experiment in which lambs were fed diets that contained 30%, 45%, 60% or 75% grain (DM basis). The results indicated that increasing the grain level improved the average daily weight gain, hot carcass weight, DM digestibility and feed conversion linearly (P < 0.01); however, feed intake was not affected. Ruminal pH decreased linearly as the grain content was increased (P < 0.01). Ruminal propionate concentration increased and acetate concentration declined with increased grain content (P < 0.01). Leptin mRNA expression in perirenal adipose tissue increased linearly (P < 0.05) as grain content increased. Based on these results, we conclude that increasing grain level in the diets of finishing feedlot lambs improved weight gain and feed efficiency; however, because weight gain and feed efficiency were similar at the higher grain levels, our data suggest including 60% grain in lamb finishing rations.

Processing of Corn and Sorghum for Feedlot Cattle

Approximately 75% to 80% of expenses involved in cattle feeding in commercial feedlots are feed costs. Grains are used in feedlot diets to improve the performance and efficiency of feedlot cattle by increasing the energy density of diets. Grains for these diets are commonly processed for various reasons, including improving palatability, altering particle size, increasing digestibility, altering the rate, site, and extent of digestion, and facilitating preservation or storage. Altering the rate, site, and extent of digestion in turn can alter cattle performance. This article focuses on processing methods common to feedlots and the primary grains fed, corn and grain sorghum.

Influence of corn and sorghum starch on the in vitro kinetics of forage fiber digestion

In vitro digestion experiments were conducted to examine the interactions of starch source and pH on kinetics and apparent extent of ruminal NDF digestion. Alfalfa hay, bromegrass hay, and each hay with either raw sorghum, raw corn, or pure corn starch in ratios to simulate a 28% NDF diet were incubated at pH 5.5, 6.2, or 6.8. Ash-free NDF was measured at 0, 6, 12, 18, 24, 30, 36, 48, 72, and 96 h of fermentation; logarithmic transformation and linear regression were used to estimate digestion parameters. Significant forage by starch interactions on lag and rate of NDF digestion and significant forage and starch by pH interactions on rate and potential extent of NDF digestion indicated that forage type must be considered when the effect of pH and starch source on NDF digestion is predicted. For both forages, raw or pure corn starch increased lag more than sorghum starch, especially at low pH. Raw sorghum starch decreased the rate of NDF digestion more for bromegrass hay than for alfalfa hay, and pure corn starch had the largest negative impact on fiber digestion, especially at low pH. Sources of starch influenced lag and rate of NDF digestion differently at pH from 6.8 to 5.5, which led to dramatic differences in apparent extent of ruminal NDF digestion.

Comparison of sorghum and corn grains in early and midlactation diets for dairy cows

Two trials were conducted to compare the effects of corn and sorghum grains on performance of early and midlactation Holstein dairy cows. In trial 1, 36 multiparous midlactation cows were assigned to one of four diets in a 2 x 2 factorial arrangement for 10 wk: 1) grain mixture containing 77% rolled corn fed in a TMR, 2) same grain fed separately from forage, 3) grain mixture containing 77% finely ground sorghum fed in a TMR, and 4) same grain fed separately from forage. Grain source and feeding methods had similar effects on milk yield, milk fat percentage, SNF, SCM, and BW. Cows fed sorghum had higher DMI; cows fed corn had greater efficiency of milk yield. In trial 2, 36 multiparous early lactation cows were assigned to one of four TMR in a 2 x 2 factorial arrangement for 9 wk: 1) TMR containing 35.5% rolled corn, 2) TMR containing 35.5% finely ground corn, 3) TMR containing 35.5% rolled sorghum, and 4) TMR containing 35.5% finely ground sorghum. Grain source produced no differences in DMI, milk yield, milk fat percentage, SCM, and BW. Cows fed finely ground grain yielded more milk than those fed rolled grain. Finely ground sorghum promoted higher milk protein and SNF percentages than did finely ground corn. Total tract starch digestibility was greater for corn than for sorghum. These two trials indicate that sorghum grain, when finely ground, supports milk yield and composition similar to that of corn.