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Effects of physically effective undigested neutral detergent fiber and rumen fermentable starch on lactation performance and total tract digestibility of lactating cows.

K. M. Smith

Abstract:

M18
Effects of physically effective undigested neutral detergent fiber and rumen fermentable starch on lactation performance and total tract digestibility of lactating cows.
K. M. Smith*1, A. Obata2, K. Hirano2, H. Uchihori2, S. Y. Morrison1, J. W. Darrah1, H. M. Dann1, C. S. Ballard1, M. D. Miller1, R. J. Grant1. 1Miner Institute Chazy, NY, 2ZEN-NOH Tokyo, Japan.

Multiparous cows (n = 16) were used in a 4 � 4 replicated Latin square design to evaluate the effect of feeding different dietary concentrations of 240-h physically effective undigested neutral detergent fiber (peuNDF240) and rumen fermentable starch (RFS) on intake, milk yield and composition, and total-tract digestibility (TTD). Diets differed in peuNDF240 and RFS by inclusion of different corn silage hybrids and cornmeal amount. Treatments were 1) low peuNDF240 (6.4%DM), low RFS (16.7%DM; LULR) 2) low peuNDF240 (6.1%DM), high RFS (19.2%DM; LUHR) 3) high peuNDF240 (8.6%DM), low RFS (16.9%DM; HULR) 4) high peuNDF240 (8.0%DM), high RFS (19.0%DM; HUHR). On d 19—28 of each 28-d period, samples for dry matter intake (DMI), milk yield, milk composition, behavior, rumen pH, rumen fluid, and TTD were taken. Data were summarized by period and analyzed with model effects of diet, period, and replicate using MIXED procedure of SAS (v.9.4). Cow within replicate was a random effect. No significant treatment differences (P > 0.05) were observed for (mean � SEM) DMI, total chewing time (809 � 14 min/d), daily mean rumen pH (6.1 � 0.1), total ammonia (7 � 10 mg/dL), and total VFA (125 � 3 mM). Cows fed LULR had higher 3.5% fat-corrected milk (FCM) compared with cows fed LUHR with HU diets being intermediate (Table 1). The LULR diet had greater TTD of neutral detergent fiber (NDF) compared with HU diets, and LU diets had lower TTD of starch compared with HU diets. Overall, this data shows that there is a balance when adding fermentable starch to diets with highly digestible fiber in the physically effective fraction, and lesser effect in diets with less digestible fiber in the physically effective fraction.Table 1.

ItemLULRLUHRHULRHUHRSEMP-value
DMI, kg/d29.729.429.429.20.70.56
Milk, kg/d53.1a52.0ab51.2b51.5ab1.30.04
Fat, %3.593.483.743.600.080.06
FCM, kg/d53.8a51.5b52.9ab52.2ab1.30.05
TTD NDF, %DM62.0a60.1ab58.6b57.6b0.590.006
TTD starch, %DM98.2b98.5b98.9a98.7a0.140.002
abLeast squares means within row without common superscript differ (P ≤ 0.05).

Keywords: undigested fiber, rumen fermentable starch, physically effective fiber.

Biography: Katherine Smith was born and raised in Blue Springs, Missouri. She received her bachelor's in Animal Science from the University of Missouri. She is currently pursuing a Master's degree from the University of Vermont through the Miner Institute in Chazy, New York.