Effects of feeding monensin to bred heifers fed in a drylot on nutrient and energy balance. (2nd April 2018)

• Record Type: Journal Article
• Authors: Hemphill, Courtney N; Wickersham, Tryon A; Sawyer, Jason E; Brown-Brandl, T M; Freetly, Harvey C; Hales, Kristin E
• Is Part Of: Journal of animal science. Volume 96:Number 3(2018)
• Page Start: 1171
• Page End: 1180
• Publication Date: 2018-04-02
• Subjects: energy balance -- heifers -- limit feeding -- monensin; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/skx030
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: The objective of this study was to determine if feeding monensin would improve diet digestion, energy and nitrogen balance in bred heifers receiving a limit-fed corn stalk-based diet. Sixteen pregnant Meat Animal Research Center (MARC ) III composite heifers were used in a 161-d completely randomized design. Heifers were randomly assigned to one of two treatments, no monensin (CON ) or 150 mg/d monensin (MON ), with eight heifers in each treatment group. Heifers were limit-fed a corn stalk-based diet at 100% of MEm requirements. Effects of monensin on energy and nitrogen balance were determined via total fecal and urine collections and open-circuit respiration calorimetry. Total fecal and urine collection occurred on d 14, 42, and 161 of monensin feeding, and calorimetry measurements were made on d 0, 3, 14, 28, 42, and 161 of monensin feeding. DMI was not different ( P = 0.94) for CON and MON heifers and, by design, increased ( P < 0.01) from d 14 to d 161 of the trial to account for increasing fetal growth requirements. No differences ( P = 0.91) in GE intake were observed between CON and MON heifers, and DE and ME intakes did not differ ( P > 0.58) with monensin inclusion. DM, OM, NDF, and ADF digestion did not differ ( P > 0.52) between treatments. Fecal, methane, urinary, and heat energy losses were not different ( P > 0.16) for MON and CON heifers. Methane production was not different between treatments when expressed as daily liters of methane ( P = 0.40); however, MON heifers produced 7% less ( P = 0.03) methane per day than CON heifers when expressed as liters of methane produced on a metabolic body weight (MBW ) basis. Furthermore, monensin had no effect ( P = 0.36) on overall retained energy (RE ). Nitrogen intake and excretion was not different ( P > 0.13) between treatment groups. Results of this experiment indicate that adding monensin to limit-fed, corn stalk-based diets may not have a large effect on the energy and nitrogen balance of confined heifers.