A Comparison of Methods to Analyze Particle Size as Applied to Alfalfa Haylage, Corn Silage, and Concentrate Mix

135

155

The objective of this experiment was to evaluate effects of reducing forage particle size on cows in early lactation based on measurements of the Penn State Particle Separator (PSPS). Eight cannulated, multiparous cows averaging 19 ± 4 d in milk and 642 ± 45 kg BW were assigned to one of two 4 × 4 Latin Squares. During each of the 23-d periods, animals were offered one of four diets, which were chemically identical but included alfalfa haylage of different particle size; short (SH), mostly short (MSH), mostly long (MLG), and long (LG). Physically effective neutral detergent fiber (peNDF) was determined by measuring the amount of neutral detergent fiber retained on a 1.18 mm screen and was similar across diets (25.7, 26.2, 26.4, 26.7%) but the amount of particles >19.0 mm significantly decreased with decreasing particle size. Reducing haylage particle size increased dry matter intake linearly (23.3, 22.0, 20.9, 20.8 kg for SH, MSH, MLG, LG, respectively). Milk production and percentage fat did not differ across treatments averaging 35.5 ± 0.68 kg milk and 3.32 ± 0.67% fat, while a quadratic effect was observed for percent milk protein, with lowest values being observed for LG. A quadratic effect was observed for mean rumen pH (6.04, 6.15, 6.13, 6.09), while A:P ratio decreased linearly (2.75, 2.86, 2.88, 2.92) with decreasing particle size. Total time ruminating increased quadratically (467, 498, 486, 468 min/d), while time eating decreased linearly (262, 253, 298, 287 min/d) with decreasing particle size. Both eating and ruminating per unit of neutral detergent fiber intake decreased with reducing particle size (35.8, 36.7, 44.9, 45.6 min/ kg; 19.9, 23.6, 23.5, 23.5 min/kg). Although chewing activity was 1445 closely related to forage particle size, effects on rumen pH were small, indicating factors other than particle size are critical in regulating pH when ration neutral detergent fiber met recommended levels. Feeding alfalfa haylage based rations of reduced particle size resulted in animals consuming more feed but did not affect milk production. (Key words: rumen, effective fiber, pH, and rumination)Abbreviation key: BWCH = body weight change, DMD = dry matter digestibility, LDR = liquid dilution rate, LG = long treatment containing long harvested haylage, MSH = intermediate short treatment composed of 1/3 parts LG, 2/3 parts SH, MLG = intermediate long composed of 2/3 parts LG, 1/3 parts SH. peNDF = physically effective neutral detergent fiber, PSPS = Penn State Particle Separator, RDOM = rumen degradable organic matter, S gm = geometric standard deviation, SH = short treatment containing rechopped alfalfa haylage, TC = total chewing activity, TLC = theoretical length of cut, X gm = geometric mean length.

Section: Discussionmentioning

confidence: 99%

The Effect of Reducing Alfalfa Haylage Particle Size on Cows in Early Lactation

Kononoff¹,

Heinrichs²

2003

135

155

“…Samples of TMR also were wet-sieved similarly except for using screens with pore sizes of 9.5, 4.75, 2.36, and 0.425 mm. A log-normal distribution was assumed (Murphy and Zhu, 1997). Cumulative proportions of 55°C DM mass retained on each screen or larger were plotted against the logarithms (base 10) of screen size.…”

Section: Methodsmentioning

confidence: 99%

Chewing, rumen pool characteristics, and lactation performance of dairy cows fed 2 concentrations of a corn wet-milling coproduct with different forage sources

Shepherd

Firkins

VonBehren

2014

We used a novel corn wet-milling coproduct [CMP; approximately 70% dry matter, 28% crude protein, 36% neutral detergent fiber (NDF), and 18% nonstructural carbohydrates] in diets formulated to contain 18.4% forage NDF, 17.4% crude protein, 20.2% starch, and 3.7% sugar. Six primiparous, rumen-cannulated Jersey cows were assigned to a 6 × 6 Latin square design with a 2 × 3 factorial arrangement of treatments. Diets were formulated to contain 20 and 30% CMP with 3 forage sources [corn silage (CS) and 40.5% NDF, CS replaced with 10% alfalfa hay (AH) and 45.0% NDF, or CS replaced with 7% grass hay (GH) and 67.4% NDF], with each providing 18.4% forage NDF in the diet. Total-tract digestibilities of NDF, N, and organic matter were not affected by treatment. Similarly, no treatment effects were detected for kinetics of NDF disappearance in situ from CMP or respective forage source or for N disappearance in situ from CMP. Grass hay increased total and liquid pool size of rumen contents compared with AH (by 3.2 and 3.0kg, respectively). Total time spent chewing increased in cows fed GH by over 35min compared with those fed AH, partially due to a trend for increased minutes spent ruminating. Mean particle size of rumen contents also tended to be higher in the GH (0.55mm) than AH (0.69mm) diets. No effects on production of milk or milk components were detected, but dry matter intake (DMI) tended to decrease when CMP increased from 20 to 30%. Gross feed efficiency (fat-corrected milk/DMI) tended to be greater when cows were fed AH and GH compared with CS and was greater for AH than GH diets. In diets containing low starch, increasing CMP from 20 to 30% potentially maintained similar fat-corrected milk production with lower DMI. However, more consideration also should be given to interactions among forages with respect to fill, digestion, and passage of fiber with increased inclusion rates of CMP.

“…Tyler Inc., Gastonia, NC) fitted with USA standard testing sieves with varying mesh sizes of 9.50, 4.75, 2.36, 1.18, 0.600, and 0.300 mm. Arithmetic mean particle size was calculated as described by Murphy and Zhu (1997). Mean particle size and particle size distribution of the TMR samples composited by period were determined using a Penn State particle separator as described by Kononoff et al (2003).…”

Section: Animals Treatments and Experimental Designmentioning

confidence: 99%

Interactions of monensin with dietary fat and carbohydrate components on ruminal fermentation and production responses by dairy cows

Mathew

Eastridge

Oelker

et al. 2011

Variation in milk fat percentage resulting from monensin supplementation to lactating dairy cows could be due to altered ruminal fermentation with interactions of monensin with ruminal biohydrogenation of fat and ruminal carbohydrate availability. The objective of the study was to determine the effects of feeding monensin as Rumensin (R) in diets differing in starch availability (ground or steam-flaked corn), effective fiber (long or short alfalfa hay, LAH or SAH), and 4% fat (F) from distillers grains, roasted soybeans, and an animal-vegetable blend on ruminal fermentation characteristics and milk production in lactating dairy cows. Six ruminally cannulated lactating Holstein cows were used in a balanced 6×6 Latin square design with 21-d periods. The cows were fed 6 diets: (1) C=control diet with ground corn and LAH, (2) CR=C plus R, (3) CRFL=CR plus F, (4) CRFS=ground corn, R, F, and SAH, (5) SRFL=steam-flaked corn, R, F, and LAH, and (6) SRFS=steam-flaked corn, R, F, and SAH. Mean particle size of LAH was 5.00 mm and 1.36 mm for SAH. All diets were formulated to have 21% forage NDF and 40% NFC. The R tended to decrease DMI, decreased milk fat yield, and numerically lowered milk fat percentage (3.41 vs. 2.98%). Addition of F to R diets did not affect milk fat percentage. By feeding diets containing R and F, SAH tended to increase milk fat percentage for the ground-corn diet, but SAH tended to decrease milk fat percentage with steam-flaked corn (CRFL+SRFS vs. CRFS+SRFL). The steam-flaked corn increased total-tract NDF digestibility (CRFL + CRFS vs. SRFL+SRFS; 51.1 vs. 56%). Addition of F with R decreased total VFA concentration and increased rumen pH. Fat addition with R decreased rumen NH3N and MUN (12.8 vs. 13.9 mg/dL), and SFC decreased NH3N concentration compared with ground corn. Although R caused milk fat depression, addition of F did not further exacerbate milk fat depression. Fatty acid analysis did not implicate any particular biohydrogenation intermediate as the causative factor for the milk fat depression.