Effect of wet or dry corn gluten feed on nutrient digestibility and milk yield and composition

Effects of inclusion of corn gluten feed in dairy rations on dry matter intake, milk yield, milk components, and ruminal fermentation parameters: a meta-analysis

Corn gluten feed (CGF) is a co-product of wet milling that can replace energy or fiber ingredients in dairy cow rations. The present meta-analysis examines how inclusion of CGF can affect dry matter intake (DMI), milk yield (MY), milk components, and ruminal fermentation parameters. A literature search was conducted to identify papers published from 1990 to 2018. Effect size for all parameters was calculated as standardized mean difference with a 95% confidence interval. Heterogeneity was determined using Q test and I² statistic, while meta-regression was used to examine factors influencing heterogeneity. Results indicate that feeding CGF increased the effect size for DMI and MY. No differences were observed for effect size for percentage milk fat or protein; however, increases were observed in the effect size for milk fat yield, milk protein yield, milk lactose percentage, and milk lactose yield. Ruminal fermentation parameters revealed a decrease in the effect size for pH and acetate and an increase for propionate. No differences were observed in the effect size for total VFA or butyrate. The Q test demonstrated heterogeneity (P < 0.1) for MY, MFP, and pH. The results indicate differences in forage intake between groups receiving CGF and control as an important factor contributing to heterogeneity for DMI, MFP, and pH. It can be concluded from this meta-analysis that in addition to increased DMI, inclusion of CGF in cow diets increases MY and improves milk components. Furthermore, inclusion of CGF in the diet lowers ruminal pH while decreasing acetate and increasing propionate contents.

Nutrient digestibility and energy value of sheep rations differing in protein level, main protein source and non-forage fibre source

Two in vivo digestion trials were conducted to evaluate the effects of diet's crude protein (CP) level, N degradability, and non-forage fibre source (NFFS) on nutrient digestibility and energy value of sheep rations. In each trial, rams were fed four isocaloric and isofibrous rations, differing in main protein and/or NFFS source. At the first trial, mean CP/metabolizable energy (ME) ratio of the diets was 17 g/MJ ME and at the second trial, 13 g/MJ ME. At both trials, the first ration contained cotton seed cake (CSC) and wheat bran (WB), the second CSC and corn gluten feed (CGF), the third corn gluten meal (CGM) and WB and the fourth CGM and CGF. Data of both trials were analysed in common as 2 x 2 x 2 factorial experimental design. Low N degradability (CGM) had positive effect on CP, neutral detergent fibre (NDF) and acid detergent fibre (ADF) digestibility of the ration. Those results suggest that an increase in rumen undegradable protein (RUP) content does not negatively affect nutrient digestibility of sheep rations. Corn gluten feed significantly elevated crude fibre (CF) digestibility, in comparison with WB. Rations having high CP/ME ratio had higher digestibility of CP in comparison with those having low CP/ME ratio; the opposite was true for ether extract, CF, NDF and ADF digestibilities. CP level x N degradability interaction negatively affected energy value of the rations that had high CP level and high N degradability. Former suggest that when CP content is high then N degradability should be low otherwise ration's ME is negatively affected. CP digestibility and coefficient q of the rations containing WB and having high N degradability (N degradability x NFFS interaction) were the lowest suggesting that the combination of CSC and WB negatively affected CP digestibility and energy value of the ration. This could be explained by a reduced microbial CP synthesis, or lower RUP digestibility or both.

Effects of diet on short-term regulation of feed intake by lactating dairy cattle

Physical and chemical characteristics of dietary ingredients and their interactions can have a large effect on dry matter intake (DMI) of lactating cows. Physical limitations caused by distension of the reticulo-rumen or other compartments of the gastrointestinal tract often limit DMI of high producing cows or cows fed high forage diets. Fermentation acids also limit DMI from a combination of increased osmolality in the reticulo-rumen and specific effects of propionate, although the mechanisms are not clear. The specific physical and chemical characteristics of diets that can affect DMI include fiber content, ease of hydrolysis of starch and fiber, particle size, particle fragility, silage fermentation products, concentration and characteristics of fat, and the amount and ruminal degradation of protein. Site of starch digestion affects the form of metabolic fuel absorbed, which can affect DMI because absorbed propionate appears to be more hypophagic than lactate or absorbed glucose. Dry matter intake is likely determined by integration of signals in brain satiety centers. Difficulty in measurement and extensive interactions among the variables make it challenging to account for dietary effects when predicting DMI. However, a greater understanding of the mechanisms along with evaluation of animal responses to diet changes allows diet adjustments to be made to optimize DMI as well as to optimize allocation of diet ingredients to animals. This paper discusses some of the characteristics of dietary ingredients that should be considered when formulating diets for lactating dairy cows and when allocating feeds to different groups of animals on the farm.

Effects of source of carbohydrate and protein and rumen-protected methionine on performance of cows

Multiparous Holstein cows were fed diets consisting of alfalfa silage, corn silage, and a concentrate mixture containing primarily ground shelled corn or corn gluten feed; the diets were supplemented with 0 or 20 g/d of rumen-protected Met. The 183-d experimental period followed a 21-d covariate period beginning at calving. Data from early lactation (d 22 to 105) and the entire experiment were analyzed. Yields of milk and milk crude protein were not affected by treatment. Corn gluten feed increased the percentages of milk fat and total solids. The rumen-protected Met tended to increase both the crude protein and casein N content of milk. Body weight, milk fat percentage, and yields of milk fat, 3.5% fat-corrected milk, and total solids were greater when ground shelled corn and 20 g/d of rumen-protected Met or corn gluten feed and 0 g/d of rumen-protected Met were fed than when ground shelled corn and 0 g/d of rumen-protected Met or corn gluten feed and 20 g/d of rumen-protected Met were fed. A similar interaction for dry matter intake was significant only during d 22 to 204. Corn gluten feed increased plasma concentrations of His, Ile, Leu, and Val. Rumen-protected Met increased plasma concentrations of Met, decreased His, and tended to decrease Arg, Lys, and Orn. These data suggest that the dietary source of carbohydrate and protein can modulate the response of cows to rumen-protected Met.

Effects of feeding nonforage fiber sources on site of fiber digestion

Although many nonforage fiber sources have high extents of neutral detergent fiber (NDF) digestion, most have rates of digestion similar to or slower than the rates of forage NDF digestion. Rates of NDF digestion vary considerably among and within sources of by-products. Digestion kinetics also vary because of the technique used (in vitro versus in situ) and because of high amounts of dietary concentrate. Based on available data for passage rate and specific gravity measurements, rates of passage of nonforage fiber sources from the rumen of high producing cows appear to be faster than those of forages. Therefore, the potential to shift NDF digestion to the hindgut has been discussed. To account for variability in ruminal and total tract digestibility of NDF, multiple regression analysis was used to indicate that nonforage NDF percentage in the diet had about two-thirds the positive response on total tract NDF digestion that forage NDF percentage did. Although the loss of potentially digestible NDF may occur, DMI does not appear to decrease much until forage NDF is below 14 to 16% of dietary DM. Conversely, replacement of starch with nonforage NDF appears to increase digestibility of fiber, mostly in diets with high concentrations of nonfiber carbohydrates, apparently because of reduced negative associative effects. Increasing the concentration of total NDF above 35% also can decrease DMI with little improvement in NDF digestibility. Increased knowledge of the kinetics of digestion and the passage of various nonforage fiber sources used to replace forage or concentrate should increase the accuracy and precision of dynamic models, thereby increasing the flexibility and utility of nonforage fiber sources in dairy rations.

Quantitative evaluation of fiber from nonforage sources used to replace alfalfa silage

The effectiveness of NDF from nonforage fiber sources was evaluated in two trials using midlactation Holsteins. Dietary NDF was added to the basal diet using either alfalfa silage or a nonforage high fiber feed. Diets were fed for 21 d. In trial 1, four amounts of alfalfa were fed. Basal milk fat percentage was 2.61% at 144 g of alfalfa NDF/kg of diet and increased linearly by .066 for each additional 1% alfalfa NDF added, up to 22.8 g of alfalfa NDF/kg of diet. Based on one amount of added nonforage fiber, the ratio of fat test increase to NDF added was .014 for brewers grains, .040 for oat hulls, and .047 for corn gluten feed. In trial 2, one amount of added alfalfa and each nonforage fiber source was used. The ratio of fat test increase to added NDF was .094 for alfalfa, .043 for brewers grains, .067 for oat hulls, .038 for corn gluten feed, .041 for beet pulp, and .044 for malt sprouts. When added to low fiber diets, NDF from the nonforage fiber sources elevated milk fat concentration approximately one-half as effectively as did NDF from alfalfa. Chewing activity was less affected by nonforage NDF than was milk fat concentration.