Growth Performance Of Beef Heifers Research Articles

249 Effects of sorghum silage kernel processing on growth performance and blood metabolites of beef heifers

Abstract Our previous studies suggested that using a shredlage (SHRD) processor or a conventional (CONV) sorghum kernel processor leads to similar apparent total tract nutrient digestibility of whole plant sorghum silage (WPSS). This study evaluated the effects of feeding WPSS harvested using different kernel processors (CONV vs. SHRD), on growth performance of beef heifers. Grain sorghum (ADV2450IG; Advanta Seeds, Argentina) was harvested at the hard-dough stage with a Class Jaguar 950 (Harsewinkel, Germany), switching the kernel processor to generate the forage material for the two treatments: CONV and SHRD. The material was bagged in two 2.7 m diameter bags and allowed to ferment for 3 mo. Black Angus heifers [n = 96; body weight (BW) = 15 ± 1 mo, 249.6 ± 28.6 kg] were blocked by initial BW, and randomly assigned to pens (8 heifers/pen, 6 pens/treatment). Diets consisted, all in DM basis, of WPSS of each respective type (SHRD or CONV) at 90.5%, expeller soybean meal at 7.0%, and a vitamin-mineral-NNP concentrate at 2.5%. The experiment consisted of a 14-d adaptation period, followed by a 56-d growing period; and feed was offered once daily. Data were analyzed as a randomized complete block design, using pen as the experimental unit, with the fixed effect of treatment and the random effect of block. No differences were observed (P > 0.10) for final BW, dry matter intake, and residual feed intake. However, CONV fed heifers tended to gain more BW per day (ADG, 0.83 vs. 0.77 kg/d; P = 0.07) and had greater gain to feed ratio (GF, 0.083 vs. 0.075 kg/kg; P = 0.05) and greater Kleiber ratio (KR, 12.1 vs 11.2 g/kg; P = 0.05) as compared with SHRD fed heifers. Furthermore, performance calculated dietary Net Energy of gain (NEg) in CONV fed heifers tended to be greater than that for SHRD (0.70 vs. 0.65 Mcal/kg of diet DM, respectively; P = 0.06). Moreover, blood serum from CONV fed heifers had 16% greater total bilirubin (P = 0.04), 12% greater cholesterol (P = 0.02), and slightly greater non esterified fatty acids (P = 0.03) concentrations. Noteworthy, serum concentrations of total bilirubin were correlated (P ≤ 0.03) with ADG, GF, KR and NEg. In conclusion, the type of kernel processor utilized for the harvest of sorghum silage may have an impact on feed efficiency of beef cattle. These differences could be related to changes on the site of utilization of nutrients, particularly starch; what could also explain the differences on blood metabolites. However, further research is needed to help explain these findings.

Effects of monensin on growth performance of beef heifers consuming warm-season perennial grass and supplemented with sugarcane molasses.

The objective of this study was to evaluate the effects of monensin on performance of beef heifers fed warm-season forages. Brangus heifers (n = 24) were stratified by BW and BCS, and randomly assigned into 1 of 12 bahiagrass pastures (1.2ha and 2 heifers/pasture). Heifers were offered 14kg of sugarcane molasses and 3.5kg of cottonseed meal weekly from day 0 to 84. Treatments were randomly assigned to pastures (6 pastures/treatment) and consisted of heifers supplemented with or without 200mg/day of monensin. On d 85, heifers were allocated to individual drylot pens, provided free choice access to bermudagrass hay, and received their respective treatment for 10d of adaptation and 11d of data collection. Monensin did not impact (P ≥ 0.13) heifer BW, BCS, overall ADG, bahiagrass IVDOM, CP, herbage mass, and allowance. Supplement disappearance after 10 and 34h of supplementation was greater for control vs. monensin heifers (P = 0.04) and tended to be greater for control vs. monensin heifers 24h post-supplementation (P = 0.07). Plasma concentrations of glucose, IGF-1, and BUN (P ≥ 0.24) did not differ between treatments. From d 85 to 106, forage and total DM intake, in vivo DM digestibility, and heifer growth performance did not differ between treatments (P ≥ 0.12). Therefore, adding monensin to sugarcane molasses-based supplements decreased supplement consumption rate, but did not impact growth and blood parameters of heifers grazing warm-season grasses with limited nutritive value.

Wheat middlings in roughage-based or limit-fed, high-concentrate diets for growing calves (1998)

A 101-day growing study was conducted to evaluate the growth performance of beef heifers fed wheat middlings in traditional full- fed, sorghum silage-based rations and in limit-fed, high-concentrate rations. Diets were formulated without wheat middlings or with wheat middlings replacing 33, 67, or 100% of rolled corn plus soybean meal. Daily gains decreased linearly (P<.01) with increasing levels of wheat middlings in the roughage-based diets because of lower feed intake (P<.10), but feed efficiency was not affected (P>.30). For the limit-fed diets, heifer daily gains decreased linearly (P<.01) as the proportion of wheat middlings in the diet increased, resulting in a linear reduction (P<.01) in feed efficiency. Wheat middlings can be utilized effectively as the predominant energy/protein source for growing cattle, though their nutritional and economic value, relative to corn and soybean meal, may be different for roughage-based and limit-fed diets.