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F. Añez-Osuna, G. B. Penner, P. G. Jefferson, H. A. Lardner, J. J. McKinnon, Effects of alternate day supplementation at two levels of energy on intake, rumen fermentation, and digestibility of beef heifers fed cool-season perennial grass hay, Journal of Animal Science, Volume 95, Issue 1, January 2017, Pages 407–419, https://doi.org/10.2527/jas.2016.1063
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Abstract
A study was conducted to evaluate the effects of supplementing energy daily vs. on alternate days at levels that were 1.5 and 2 times the daily amount on DMI, rumen fermentation parameters, and apparent total tract digestibility of beef heifers fed grass hay. Four cannulated Hereford heifers (339 ± 11 kg) were randomly assigned over 4 periods to a 4 × 4 Latin square design. Heifers were fed a cool-season perennial grass (CSPG) hay (10% CP and 42% ADF) and supplemented with a pelleted feed formulated to provide 3.2 Mcal/kg of DE. Treatments consisted of a nonsupplemented control (CON) and 3 supplemented treatments where the supplement was offered daily at 0.6% BW (DLY) or on alternate days at 0.9% BW (LA) and 1.2% BW (HA). Heifers fed DLY had lower (P ≤ 0.04) CSPG hay DMI (7.1 vs. 8.1 kg/d) and mean ruminal pH (6.65 vs. 6.75) and greater (P < 0.01) total short-chain fatty acid (SCFA; 77.1 vs. 69.2 mM) and NH3–N (4.6 vs. 3.4 mg/dL) concentrations in ruminal fluid than CON heifers. The concentration of ruminal NH3–N for LA (5.8 mg/dL) was greater (P < 0.01) than for DLY. Total tract DM digestibility was greater for DLY (52.5%; P ≤ 0.03) than for CON (44.2%) and LA (49.7%), whereas no effects were found (P ≥ 0.11) for DLY vs. HA. When data was analyzed for days when LA and HA were supplemented, hay DMI was greater (P < 0.05) for DLY (7.3 kg/d) vs. HA (6.0 kg/d) but not different (P = 0.16) vs. LA (6.4 kg/d), mean ruminal pH of DLY (6.64) was greater vs. HA (6.59; P = 0.04) and tended to be greater vs. LA (6.60; P < 0.09), and total SCFA concentration of DLY (77.9 mM) was lower (P < 0.01) vs. HA (88.2 mM) and tended (P = 0.08) to be lower vs. LA (84.0 mM). On days when LA and HA were not supplemented, hay DMI was not different (P ≥ 0.48) for DLY vs. LA and HA, mean ruminal pH was greater (P ≤ 0.03) for LA (6.79) and HA (6.85) compared with DLY (6.67), and total SCFA concentration of DLY (76.2 mM) was not different (P = 0.15) vs. LA (67.5 mM) but greater (P = 0.03) vs. HA (62.0 mM). These results show that reducing the amount of supplement fed on alternate supplementation programs from 2 to 1.5 times the amount of daily programs can minimize the negative effects on rumen fermentation and forage DMI.
