Effects of supplement type on performance, reproductive, and physiological responses of Brahman-crossbred females.
Two experiments were conducted to compare the performance and physiological responses of forage-fed beef females supplemented with either a molasses-based (ML) or a citrus pulp-based (CT) supplement. In Exp. 1, BW gain, reproductive performance, and concentrations of blood urea N (BUN), plasma glucose, insulin, IGF-I, and progesterone (P4) were assessed in 60 Brahman x Angus heifers supplemented 3 times weekly with either ML or CT. Supplement intakes were formulated to be isocaloric and isonitrogenous. Reproductive performance was not affected by treatments, but mean BW gain was greater (P < 0.01) for heifers fed CT than for those fed ML (0.40 vs. 0.30 kg/d). Mean plasma concentrations of glucose, insulin, and IGF-I were greater (P < 0.05) for heifers fed CT, whereas BUN was greater (P < 0.05) for heifers fed ML. Mean plasma P4 concentration did not differ between treatments, but both groups had lower plasma P4 concentrations during days that supplements were offered (P < 0.01). In Exp. 2, forage DMI and concentrations of BUN, plasma glucose, insulin, IGF-I, and P4 were assessed in 24 Brahman x British mature cows supplemented with the same treatments described in Exp. 1. Overall forage DMI did not differ between treatments, but a day effect and a treatment x day interaction were detected (P < 0.05). Both groups consumed less forage during the days on which the supplements were offered (P < 0.01), and forage DMI for cows fed CT was less (P < 0.05) than for cows fed ML during those days. No differences were detected in any blood or plasma measurement. In addition, no differences in concentrations of P4 were detected between CT- and ML-fed cows. We concluded that CT-supplemented heifers had greater BW gain compared with ML-supplemented heifers, but no differences in reproductive performance were observed. We also observed that CT-supplemented cows had a greater variability in forage DMI compared with ML-supplemented cows.
Cooke
R F
RF
University of Florida, Institute of Food and Agricultural Sciences, Range Cattle Research and Education Center, Ona 33865, USA.
Arthington
J D
JD
Staples
C R
CR
Thatcher
W W
WW
Lamb
G C
GC
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001806:Blood Urea Nitrogen; D002417:Cattle / Q000097:blood / Q000254:growth & development* / Q000502:physiology*; D002957:Citrus; D003433:Crosses, Genetic; D019587:Dietary Supplements; D002149:Energy Intake / Q000187:drug effects / Q000502:physiology; D005260:Female; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008965:Molasses; D011247:Pregnancy; D018873:Pregnancy Rate; D011374:Progesterone / Q000097:blood; D011897:Random Allocation; D012098:Reproduction / Q000502:physiology*; D015430:Weight Gain
D001786:Blood Glucose; D007328:Insulin; D011374:Progesterone; D007334:Insulin-Like Growth Factor I