Comparative Feeding Value of Supplemental Fat in Finishing Diets for Feedlot Steers Supplemented with and Without Monensin

Abstract

Two comparative slaughter trials and a metabolism trial were conducted. Treatments consisted of: 1) 0 fat, 0 monensin; 2) 4% yellow grease, 0 monensin; 3) 0 fat, 33 mg/kg monensin and 4) 4% yellow grease, 33 mg/kg monensin. Trial 1 involved 104 crossbred beef steers (267 kg) in a 140-d comparative slaughter trial. There were no interactions (P greater than .20) between supplemental fat and monensin on steer performance. Monensin supplementation decreased rate of weight gain (P less than .10) and feed intake (P less than .05) with no effect on energy value of the diet (P greater than .20). Fat supplementation increased (P less than .01) rate of weight gain 12.5% and increased the net energy for maintenance (NEm) and net energy for gain (NEg) value of the diet 8.5 and 9.4%, respectively. Trial 2 involved 154 Holstein steers (290 kg) in a 94-d comparative slaughter trial. There were no interactions between supplemental fat and monensin (P greater than .20). Monensin supplementation did not affect rate or composition of gain (P greater than .20), but supplementation reduced (P less than .05) feed intake and feed required per unit weight gain 3.6%. Fat supplementation increased (P less than .01) fat and energy gain 12.5 and 10.3%, respectively, and the NEm and NEg content of the diet 7.5 and 8.4%, respectively. Trial 3 utilized four crossbred beef steers (220 kg) with cannulas in the rumen, proximal duodenum and distal ileum. There were no interactions between supplemental fat and monensin with respect to site of digestion (P greater than .20). Supplemental fat did not affect (P greater than .20) organic matter, starch, fiber or N digestion. Intestinal digestibility of fat averaged 77.3%. Monensin increased (P less than .10) intestinal digestibility of fat 7.4%. There were negative associative effects between supplemental fat and monensin on ruminal acetate:propionate ratios and estimated methane production. It was concluded that the feeding value of feed fat is underestimated in tables of feed standards currently in use, and that the net effects of monensin on these estimates are additive.

Factors affecting intestinal starch digestion in ruminants: A review

“…Zinn et al (2002) summarized available literature and suggested that post-ruminal starch digestion appears to be limited by accessibility of the amylolytic enzymes and not limitations in the amount of enzymes. It is Karr et al (1966), Hibberd et al (1985), Axe et al (1987), Zinn (1988Zinn ( , 1989Zinn ( , 1990Zinn ( , 1991, Streeter et al (1989Streeter et al ( , 1990Streeter et al ( , 1991, Hill et al (1991), Palmquist et al (1993), Streeter and Mathis (1995), Swingle et al (1999), Theurer et al (1999), Garcia et al (2000).…”

Interaction of Dietary Selenium and Magnesium Level on Digestive Function in Lambs Fed High-concentrate Diets

“…Samples were subjected to all or part of the following analysis: DM, ash, Kjeldahl N, ammonia N (AOAC, 2003); purines (Zinn and Owens, 1986); VFA concentrations of ruminal fluid (gas chromatography; Zinn, 1988); selenium and magnesium (atomic absorption spectrophotometry); chromic oxide (Hill and Anderson, 1958); NDF (Weizhong and Uden, 1998) and starch (Zinn, 1990).…”

Efeito da combinação de óleo de soja e monensina na dieta sobre o consumo de matéria seca e a digestão em vacas lactantes

“…A associação de óleo e monensina diminuiu a concentração de acetato em relação ao óleo, mas não deferiu da monensina, sugerindo que a população microbiana sensível à monensina não é a mesma que aquela sensível ao óleo de soja, ou também, que a microbiota ruminal apresenta diferentes graus de sensibilidade em relação ao ionóforo ou ao óleo de soja. Resultados semelhantes foram observados por Zinn (1988), utilizando graxa amarela e monensina.…”

“…A proporção entre os AGV também foi alterada, com redução de acetato e elevação de propionato, no entanto, sem apresentar interação entre os tratamentos. Zinn (1988) não constatou interação entre graxa amarela (resíduo de gordura de restaurantes) e monensina sobre o desempenho animal, mas os produtos finais da fermentação ruminal foram alterados. Cant et al (1997) registraram efeito sinérgico entre monensina e óleo de peixe ao reduzir o consumo por vacas lactantes.…”