Effect of live weight gain of steers during winter grazing: III. Blood metabolites and hormones during feedlot finishing12

Abstract

Two experiments were conducted using 48 Angus x Angus-Hereford steers in each experiment to determine the effect of previous winter grazing BW gain on jugular concentrations of metabolites and hormones during feedlot finishing. In each experiment, steers were randomly assigned to one of three treatments: 1) high rate of BW gain grazing winter wheat (HGW), 2) low rate of BW gain grazing winter wheat (LGW), or 3) grazing dormant tallgrass native range (NR) with 0.91 kg/d of a 41% CP (DM basis) supplement. Steers grazed for 120 or 144 d in Exp. 1 and 2, respectively. Plasma and serum were collected from all steers before placement into a feedlot, and six or seven times during finishing in Exp. 1 and 2, respectively. In Exp. 1, before steers entered the feedlot, concentrations of insulin, triiodothyronine (T3), and thyroxine (T4) were greater (P < 0.05) in HGW than in LGW or NR steers, and concentrations of IGF-I and plasma urea-N were greater (P < 0.05) in steers that grazed wheat pasture than in NR steers. In Exp. 2, concentrations of glucose, T3, T4, and IGF-I were greater (P < 0.05) in steers that grazed wheat pasture than NR steers. In Exp. 1 (P < 0.19) and 2 (P < 0.86), glucose concentration did not differ among treatments during finishing. In Exp. 1, insulin concentration across days on feed was greater for HGW than LGW steers, which were greater than for NR steers (treatment x day interaction, P < 0.03). In Exp. 2, insulin concentration increased (P < 0.001) as days on feed increased. Concentrations of IGF-I were greater in steers that had grazed wheat pasture, whereas the increase in IGF-I with increasing days on feed was greater for NR steers (treatment x day interaction, P < 0.003). Concentrations of T3 and T4 during finishing were greater (P < 0.001) in HGW and LGW than in NR steers in Exp. 1. In Exp. 2, T4 concentration also differed (P < 0.009) among treatments (HGW > LGW > NR). In Exp. 2, final concentration of glucose was greater (P < 0.01) in NR than in HGW and LGW steers, and serum insulin concentration was greater (P < 0.04) in NR than LGW steers. Final concentrations of T3 (P < 0.01) and T4 (P < 0.004) were greater in NR than in HGW steers. Our data show that previous BW gain can affect blood metabolites and hormones in steers entering the feedlot. However, lower concentrations of T3, T4, and IGF-I in steers when they entered the feedlot did not inhibit the growth response of previously restricted steers.

Influence of the diet and grazing on adipose tissue lipogenic activities and plasma leptin in steers

“…These data corroborate previous studies (Vega et al, 2002;Higashiyama et al, 2003;Hersom et al, 2004) showing increased circulating leptin levels during fattening in heifers and steers. The late increase of leptinaemia with age in Charolais steers (from 28-32 months of age in the present study, Figure 1) compared with Holstein or Japanese Black steers (from 16 to 18 months of age, Vega et al, 2002;Higashiyama et al, 2003) could be a breed-related difference due to an earlier lipid deposition in the early-maturing Holstein and Japanese Black breeds than in the late-maturing Charolais breed.…”

Effects of growth-promoting agents and season on blood metabolites and body temperature in heifers1,2

“…From this study, it appears that the early rapid gain response could be partially attributed to the rapid rise in IGF-I associated with the use of growth promotants, particularly ET combinations. Hersom et al (2004) found that IGF-I concentration is a function of the plane of nutrition. In that study, IGF-I blood concentrations were between 45 and 90 ng/ mL for cattle consuming native range, whereas cattle consuming greater quality wheat pasture had blood concentrations between 115 and 158 ng/mL.…”

Potential nutritional strategies for the amelioration or prevention of high rigor temperature in cattle – a review

“…When grazing beef cattle are introduced to concentrate feeding in a feedlot, the response is exacerbated and there is an increase in circulating glucose and insulin with time on feed ( Fig. 1) (Henry et al 2000;Hersom et al 2004c), which is also associated with increasing fatness and adipocyte cellularity (Hersom et al 2004a(Hersom et al , 2004b(Hersom et al , 2004c. Feeding of grain is also associated with an increase in core body temperature .…”

“…Expression of the leptin gene in adipose tissue and circulating leptin concentrations are highly correlated with percentage of body fat in rodents (Soukas et al 2000) and the degree of obesity in humans (Auwerx and Staels 1998). The concentration of leptin is directly related to the degree of adiposity in cattle (Ehrhardt et al 2000;Hersom et al 2004c) and sheep Chilliard et al 2005). Long-fed cattle and obese sheep tend to reduce their feed intake as they become fatter and leptin may act as a satiety factor to inhibit feed intake in fat animals that have accumulated adipose tissue.…”