Effects of feeding supplemental fat to beef cows on cold tolerance in newborn calves.
Our objectives were to examine the effects of added fat in late-gestation cow diets on neonatal response to cold. In Exp. 1, pregnant fall-calving heifers received control (n = 5), safflower seed (n = 5), or whole cottonseed (n = 5) diets. The hay-based, isonitrogenous, and isocaloric diets, fed for 47 d prepartum, contained 1.5, 4.0, and 5.0% fat for control, safflower, and whole cottonseed diets, respectively. At calving, calf BW and vigor score, as well as fat, lactose, and IgG in colostrum were not affected (P > 0.30) by diet. Heifers fed the safflower diet tended to have greater colostral solids (P < 0.10) than heifers fed the control or whole cottonseed diets. At 6.5 h of age, calves were placed in a 5 degrees C cold room for 90 min. Calf vigor, shivering, body temperature, and blood samples were taken every 15 min. During cold stress, calf body temperature decreased 0.7 degrees C (P < 0.03). Across all diets, shivering and serum glucose concentrations increased (P < 0.05), whereas calf vigor and cortisol concentrations decreased (P < 0.02) during cold exposure. In Exp. 2, pregnant spring-calving cows (n = 98) received a control (n = 47) or whole cottonseed (n = 51) supplement. Hay-based diets fed for 68 d prepartum contained 2.0 and 5.0% fat for control and whole cottonseed diets, respectively. Calf BW, vigor, shivering, dystocia score, time to stand, time to nurse, serum glucose concentrations, and serum IgG were not affected (P > 0.50) by diet. Between 30 and 180 min, body temperature of calves from dams fed the whole cottonseed supplement decreased (P < 0.05) more than calves from dams fed the control supplement. Serum glucose concentrations in calves were not affected by diet (P > 0.30). Serum cortisol concentrations tended (P < 0.09) to be greater for calves from dams fed whole cottonseed than control calves. When ambient temperature was < 6 degrees C, calves born to dams fed whole cottonseed had greater (P < 0.05) BW, tended (P < 0.1) to stand earlier, and had greater serum IgG concentrations. We conclude that calves from dams fed high-fat diets containing safflower or whole cottonseed respond similarly to cold stress, but these responses may not be consistent with greater cold resistance. In addition, high-fat dietary supplementation of late-gestation cows may only be beneficial during calving seasons with prolonged cold weather.
Dietz
R E
RE
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.
Hall
J B
JB
Whittier
W D
WD
Elvinger
F
F
Eversole
D E
DE
D000222:Adaptation, Physiological; D000821:Animal Feed; D000818:Animals; D000831:Animals, Newborn / Q000097:blood / Q000502:physiology*; D001786:Blood Glucose / Q000032:analysis; D001831:Body Temperature; D002417:Cattle / Q000097:blood / Q000502:physiology*; D003080:Cold Temperature; D003126:Colostrum / Q000737:chemistry; D004041:Dietary Fats / Q000008:administration & dosage*; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008892:Milk / Q000737:chemistry; D011247:Pregnancy; D011897:Random Allocation; D012621:Seasons; D012639:Seeds; D012768:Shivering / Q000502:physiology; D013997:Time Factors
D001786:Blood Glucose; D004041:Dietary Fats; D007074:Immunoglobulin G; D006854:Hydrocortisone