Nutrient Demand Interacts with Forage Family to Affect Intake and Digestion Responses in Dairy Cows

The objectives of this experiment were to determine the effects of forage type on nutrient digestibility, purine derivative excretion, nitrogen utilization, and milk production in dairy cattle consuming rations containing high levels of wet distillers grains with solubles (WDGS). Primiparous (n = 8) and multiparous (n = 20) Holstein cows were used in a replicated 4 × 4 Latin square. Animals were fed 1 of 4 treatments during each 21-d period: 1) CONT-CS, 0% WDGS and high corn silage; 2) CONT-AS, 0% WDGS and high alfalfa silage; 3) WDGS-CS, 25% WDGS and high corn silage; and 4) WDGS-AS, 25% WDGS and high alfalfa silage (dry matter basis). Intake and milk data were collected daily and averaged for d 15 to 21 of each period. Dry matter intake was lower for CONT-CS than for CONT-AS, WDGS-CS, and WDGS-AS (22.5, 24.6, 24.6, and 24.8 kg/d, respectively). Digestibility of dry matter, organic matter, neutral detergent fiber, and N were not affected by treatment, averaging 59.6, 62.3, 40.1, and 58.6%, respectively. Excretion of urinary purine derivatives was greatest for WDGS-AS, followed by WDGS-CS, and then CONT-CS and CONT-AS. Thus, by calculation, estimated microbial protein flow was highest for WDGS-AS (2,189.9 g/d) followed by WDGS-CS (1,996.2 g/d), CONT-AS (1,640.0 g/d), and CONT-CS (1,627.0 g/d). Mass of fecal N was not different among treatments (averaging 287.1 ± 14.8 g/d), but urinary and manure N were reduced for rations with WDGS compared with those not including WDGS. Observed 4% fat-corrected milk was greatest for WDGS-AS, followed by WDGS-CS, and then 29.7, 28.3, and 27.2 kg/d, respectively). Milk protein yield was greatest for WDGS-AS (1.00 kg/d), followed by WDGS-CS, and then CONT-AS and 0.91, 0.86 kg/d, respectively). This research demonstrated that rations can be balanced for dairy cattle to include up to 25% WDGS and result in increased microbial protein synthesis, milk production, and milk protein yield.

Section: Nutrient Intake and Digestibilitymentioning

confidence: 92%

Utilization of nitrogen in cows consuming wet distillers grains with solubles in alfalfa and corn silage-based dairy rations

Gehman

Kononoff

2010

“…Diets with a higher proportion of AS had a faster digestion rate of pdNDF (5.0-7.5%/h, Dado and Allen, 1996;Voelker Linton and Allen, 2008) than diets with more CS (2.29%/h, Oba and Allen, 2000). However, the passage rate of pdNDF was slower when diets contained a higher proportion of AS than CS (1.3%/h for AS and 3.56%/h for CS diets; Oba and Allen, 2000;Voelker Linton and Allen, 2008). An in vitro model to predict total-tract NDF digestibility with accuracy needs to estimate the extent of ruminal fiber digestion, the rate of digestion of pdNDF, and the rate of passage of the pdNDF (Mertens, 2002).…”

Section: Introductionmentioning

confidence: 92%

Effects of varying dietary ratios of corn silage to alfalfa silage on digestion of neutral detergent fiber in lactating dairy cows

Lopes

Cook

Combs

2015

An in vivo study was performed to test an in vitro procedure and model that predicts total-tract neutral detergent fiber (NDF) digestibility for lactating dairy cattle. Corn silage (CS) and alfalfa silage (AS) were used as forages for this study. These forages had similar NDF composition, but fiber in the CS contained less indigestible NDF compared with AS (35.5 and 47.8% of indigestible NDF, respectively). The in vitro method estimated rate of digestion of alfalfa potentially digestible NDF to be approximately 2 times faster than CS fiber (6.11 and 3.21%/h, respectively). Four diets were formulated containing different proportions of CS to AS: 100CS:0AS, 67CS:33AS, 33CS:67AS, and 0CS:100AS, as percentage of diet DM basis. The objective was to construct diets that contained approximately similar levels of NDF but with different pool sizes and rates of digestion of potentially digestible NDF. Diets were fed to 8 ruminally cannulated, multiparous, lactating dairy cows in a replicated 4×4 Latin square with 21-d periods. Total-tract fiber digestibility and fiber digestion kinetic parameters observed in vivo were compared with the values predicted by the in vitro assay and model. Total-tract NDF digestibility coefficients were similar (41.8 and 40.6% of total NDF) for the in vitro and in vivo methods, respectively. As the proportion of dietary alfalfa increased, the digestibility of NDF increased. The rate of digestion of potentially digestible NDF predicted from the in vitro assay was also similar to what was observed in vivo. Results suggest that the in vitro total-tract NDF digestibility model could be used to predict rate of fiber digestion and NDF digestibility for lactating dairy cattle.

“…This implies that all particles have equal probability of escape from the rumen. However, escapable (i.e., small) and nonescapable (i.e., large) particles have different passage rates (Allen and Mertens, 1988;Voelker Linton and Allen, 2008). Additionally, heterogeneous feed fractions such as NDF, which includes indigestible NDF (iNDF) and potentially digestible NDF (pdNDF), have different ruminal kinetics (Stensig and Robinson, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Digesta passage from the rumen is affected by numerous feed and animal factors. Legumes and grasses have different ruminal kinetic parameters (Voelker Linton and Allen, 2008;Bayat et al, 2010;Krizsan et al 2010) and increases in DMI result in a decrease in the percentage of small particles in the rumen (Okine and Mathison, 1991). Therefore, the effects of forage family and level of feed intake on ruminal passage rates are of interest in this study.…”

Section: Introductionmentioning

confidence: 99%

Rates of particle size reduction and passage are faster for legume compared with cool-season grass, resulting in lower rumen fill and less effective fiber

Kammes

Allen

2012

Self Cite

Effects of forage family on rates of particle size reduction in, and passage from, the rumen and the relationship of these effects with preliminary dry matter intake (pDMI) were evaluated using 13 ruminally and duodenally cannulated Holstein cows in a crossover design with a 14-d preliminary period and two 18-d treatment periods. During the preliminary period, pDMI of individual cows ranged from 19.6 to 29.5 kg/d (mean = 25.9 kg/d). Experimental treatments were diets containing either a) alfalfa silage (AL) or b) orchardgrass silage (OG) as the sole forage. Silages were chopped to 10-mm theoretical length of cut and contained 42.3 and 58.2% neutral detergent fiber (NDF) for alfalfa and orchardgrass, respectively. Both diets contained approximately 25% forage NDF and 30% total NDF. Feed, orts, rumen, and duodenal samples were wet sieved to fractionate particles above (large) and below (small) 2.36 mm. Indigestible NDF (iNDF) was used as a flow marker. Preliminary DMI, an index of nutrient demand, was determined during the last 4 d of the preliminary period when cows were fed a common diet and used as a covariate. Main effects of forage family and their interaction with pDMI were tested by ANOVA. Approximately 75% of the NDF consumed was large and 25% was small for both treatments, but cows fed AL consumed more iNDF and less potentially digestible NDF (pdNDF) than cows fed OG. The AL diet increased the reduction rate (large to small) compared with OG despite less rumination per unit of forage NDF for AL than OG, suggesting alfalfa NDF was more fragile than orchardgrass NDF. Over 55% of particles in the rumen were below 2.36 mm for AL and OG, indicating that particle size was not a limiting constraint to passage. Passage rates (k(p)) of large iNDF and large pdNDF were similar for AL and OG, but AL increased k(p) of large pdNDF and OG decreased it as pDMI increased. The AL diet increased k(p) of small iNDF and small pdNDF compared with OG, resulting in lower rumen fill for AL than OG. The k(p) of small iNDF and small pdNDF were similar within forage family, suggesting buoyancy was not limiting passage. The OG diet increased rumen pool size of large NDF compared with AL, which likely retained small NDF, contributing to the slower k(p) of small iNDF and small pdNDF observed for OG. Particle size reduction was a prerequisite to ruminal passage but not a constraint. Selective retention of small particles was less for alfalfa than orchardgrass, resulting in lower rumen fill and less effective fiber.