Virginiamycin and Caloric Density Effects on Live Performance, Blood Serum Metabolite Concentration, and Carcass Composition of Broilers Reared in Thermoneutral and Cycling Ambient Temperatures

Abstract

One experiment utilizing Cobb x Cobb male broilers was conducted to evaluate virginiamycin (VM; 0, 15, 20 ppm) and diet caloric density (CD; 2,945, 3,200 AMEn/kg) effects on broiler live performance, blood serum metabolites, and carcass composition. The starter period exposed birds to recommended brooding conditions, whereas from 3 to 7 wk birds were exposed to thermoneutral (TN, 24 C) or cycling temperature (CT, 24 to 35 C) environments (E). During the 21-d starter period, VM levels and high CD increased (P < 0.05) BW gain (G) and gain:feed (G:F) improved (P < 0.05) with 20 ppm VM and high CD. During 3 to 7 wk, CT reduced (P < 0.05) most live performance and carcass variables as well as heat production (HP) and energetic efficiency whereas energy content per gram of tissue increased. The main effect of VM and CD on blood serum constituents was not significant; however, CT decreased (P < 0.05) serum Na, K, Ca, Mg, Fe, albumin, and total protein. Within CT, G increased (P < 0.05) with high CD and with the 15 ppm VM combination, whereas within TN, G was unaffected by CD, but increased (P < 0.05) with the 20 ppm VM and low CD combination compared with the control. High CD increased (P < 0.05) BW, G, carcass weight, dressing percentage, carcass percentage fat, carcass dry matter, carcass energy content per bird, HP, fat, and protein gain but reduced (P < 0.05) carcass percentage protein and energetic efficiency. Carcass weight, breast yield, fat, and protein gains as well as dry matter carcass energy content increased (P < 0.05) with VM compared with controls. The reduced (P < 0.05) calorie intake and HP with concomitant increase (P < 0.05) in calorie gain with 20 ppm VM increased (P < 0.05) caloric efficiency. In summary, the results suggest that VM improves bird performance by reducing HP and that reduced HP during high CT improves body temperature homeostasis.

Blood Plasma Mineral Profile and Qualitative Indicators of the Eggshell in Laying Hens in Different Housing Systems

“…Suchy et al (2001) and Kurtoglu et al (2001) reported mean Ca levels similar to the mean values found in our experiment. Our values also fall within the physiological range as described by Belay and Teeter (1996). Lower values as compared with our results were reported by Koelkebeck and Odom (1995), Sahin et al (2002b), and Eren et al (2004).…”

“…The values we obtained from all the housing systems ranged within mean values reported e.g. by Jerabek et al (1993), Koelkebeck and Odom (1995), Belay and Teeter (1996), Kaya et al (2001), Suchy et al (2001), Sahin et al (2002a), and Thiemel and Jelinek (2004). Substantially higher values were published by Eren et al (2004), whereas lower values were reported by Kurtoglu et al (2001).…”

Effect of energy density and virginiamycin supplementation in diets on growth performance and digestive function of finishing steers

“…In broiler chickens under condition of heat stress, enhanced growth performance with VM supplementation was likewise associated with decreased heat production and related heat distress mortality, and improved energetic efficiency. Belay and Teeter [ 25 ] suggested that observed response to VM supplementation was partly attributable to improved temperature homeostasis of chickens under conditions of heat stress. Consistent with this earlier work involving poultry, we likewise found that VM supplementation does in fact lower core temperatures in cattle.…”

Rethinking our understanding of the pathogenesis of necrotic enteritis in chickens

“…Added in low doses to the feed of farm animals, they have been shown to increase daily weight gain and conversion of feed into body mass, leading to economic advantages for farmers 2,3,4,5 . However, there is an increasing trend to reduce this use of antibiotics in feedstuffs.…”