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This Article Full Text (PDF) All Versions of this Article: jas.2008-1125v1 87/2/612    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Gaughan, J. B. Articles by Mader, T. L. Search for Related Content PubMed PubMed Citation Articles by Gaughan, J. B. Articles by Mader, T. L.

Effects of sodium chloride and fat supplementation on finishing steers exposed to hot and cold conditions

J. B. Gaughan^* and T. L. Mader

^* School of Animal Studies, The University of Queensland, Gatton, Australia, 4343 Haskell Agricultural Laboratory, University of Nebraska-Lincoln, Concord, NE 68728

j.gaughan{at}uq.edu.au

Abstract

Three studies were conducted to evaluate the effects of supplemental fat and salt (NaCl) on DMI, water intake (DWI), body temperature, and respiration rate (RR) in Bos taurus beef cattle. In Exp. 1 and Exp. 2, whole soybeans (SB) were used as the supplemental fat source. In Exp. 3, palm kernel meal and tallow were used. Exp. 1 (winter) and Exp. 2 (summer) were undertaken in an outside feedlot. Exp. 3 was conducted in a controlled climate facility (mean ambient temperature = 29.9^oC). In Exp. 1, 3 diets (i) control, (ii) salt: control + 1% NaCl, and (iii) salt-SB: control + 5% SB + 1% NaCl were fed to 144 cattle (BW = 327.7 kg) utilizing a replicated 3 x 3 Latin square design. In Exp. 2, 168 steers (BW = 334.1 kg) were used. In Exp. 2, the same dietary treatments were utilized as Exp. 1 plus a 5% SB dietary treatment were included in an incomplete 3 x 4 Latin square design. In Exp. 3, 3 diets (i) control, (ii) salt: control + 0.92% NaCl, and (iii) salt-fat: control + 3.2% added fat + 0.92% NaCl were fed to 12 steers (BW = 602 kg) in a replicated Latin square design. In Exp. 1, cattle fed salt-SB had elevated (P < 0.05) tympanic temperature (TT; 38.83^oC) compared to cattle fed control (38.56^oC) or salt (38.50^oC). In Exp. 2, salt and salt-SB treatments had lower (P < 0.05) DMI and greater (P < 0.05) DWI than control and SB treatments. Cattle fed the salt-SB diet had the highest (P < 0.05) TT (38.89^oC). Those fed only the salt or only the SB diets had the lowest (P < 0.05) TT at 38.72^oC and 38.78^oC, respectively. Under hot conditions (Exp. 3), DMI of salt fed and salt-fat fed steers fell by approximately 40% vs. only 24% for the control cattle. During hot conditions DWI was greatest (P < 0.05) for the salt-fat steers. These steers also had the highest (P < 0.05) mean rectal temperature (40.03 ± 0.1°C) and RR (112.7 ± 1.7 breaths/min). The RR of control steers was the lowest (P < 0.05; 98.3 ± 1.7 breaths/min). Although added salt plus fat lowered DMI under hot conditions, these data suggest switching to diets containing the combination of added salt and fat elevates body temperature, which would be a detriment in the summer but a benefit to the animal during winter. Nevertheless, adding salt plus fat to diets resulted in increased DWI under hot conditions. Diet ingredients or combination of ingredients that can be used to regulate DMI may be useful to limit large increases in DMI during adverse weather events.

Key Words: beef cattle • environmental stress • fat • salt