Effect of flint corn processing method and roughage level on finishing performance of Nellore-based cattle1

Abstract

This study was conducted to evaluate the effects of flint corn processing method (CPM) and level of NDF from roughage (rNDF) on performance, carcass characteristics, and starch utilization by finishing Nellore-based cattle fed high-concentrate, flint corn-based diets. In this study, 112 Nellore type bulls (initial BW 384.07 ± 29.53 kg and 24-36 mo of age) were individually fed using Calan gates or individual pens. The animals were used in a randomized complete block design in a 2 × 4 factorial arrangement with 2 CPM, high-moisture flint corn (HMC) or finely ground dry flint corn (FGC), with 1 of 4 levels of rNDF, 3, 8, 13, and 18% (DM basis), using sugarcane silage (SS) as roughage. Bulls were adapted to the finishing diet over a 21-d period and fed for a total of 81 d. Fecal starch (FS) concentration was determined on d 46 and 74 of the feeding period. There was a quadratic effect of rNDF on final BW (P < 0.01) and ADG (P = 0.01). Optimal concentrations of rNDF were estimated using the first derivative of second order polynomials, indicating that final BW and ADG were maximized with 13.3 and 13.0% rNDF, respectively. An interaction was observed between CPM and rNDF (P = 0.05) for DMI, with peak DMI occurring at 11.3 and 13.7% rNDF with FGC and HMC, respectively. Cattle fed HMC had 13.9% greater G:F (P < 0.01) compared with those fed FGC (0.172 vs. 0.151, respectively). There were quadratic effects of rNDF on HCW (P = 0.04) and ME intake (P < 0.01); heaviest carcass weights were estimated, in both cases, to be achieved with 12.8% rNDF. A quadratic effect of rNDF for renal, pelvic, and inguinal fat weight (P = 0.04) was observed, with a peak estimated to occur at 12.6% rNDF. An interaction between CPM and rNDF also was observed for FS (P < 0.05). Bulls fed FGC with 3% rNDF had greater FS content, and FS linearly decreased as concentration of rNDF increased. For bulls fed HMC, FS was 3.0% of DM and was unaffected by rNDF in the diet. Lower FS from bulls fed HMC suggests that availability of starch from flint corn was greater than that of FGC. For Nellore-based cattle fed a flint corn-based diet containing SS and 8% whole lint cottonseed, performance was optimized with 12.8% rNDF. In the absence of cottonseed addition to diets, optimal performance would be expected with about 14.5% rNDF.

<b>Levels of concentrate and sources of non-fiber carbohydrates on productive performance and ruminal kinetics of finishing cattle</b>

“…Another study evaluated levels of in natura sugarcane bagasse in diets that contained ground corn and citrus pulp -a great source of fiber, in the concentrate, and concluded that the animal performance was increased when 15% of bagasse was increased in the diet (BULLE et al 2002). If the bagasse is considered to have 85% of NDF the rNDF of the 15% -bagasse diet would be 12.75%, similar to the value reported by Caetano et al (2015). In the present study, the rNDF of the 80% concentrate diets were 12.8% and the 60% diets were 25.7%.…”

“…For Nkrumah et al (2006), feed efficiency may be influenced by several potential metabolic and physiological pathways such as efficiency of conversion of gross energy into metabolizable energy (because of differences in digestibility, generation of gases during ruminal fermentation, absorption of nutrients, waste excretion, and heat production) and the subsequent efficiency of metabolizable energy conversion to retained energy for maintenance and growth. Caetano et al (2015) evaluated either high-moisture or finely-ground flint corns and levels of roughage NDF (rNDF) in sugarcane silage-based diets with 8% of whole lint cottonseed, and concluded that the high-moisture corn (HMC) decreased the DMI but increased the G:F ratio, with no effects on the ADG. They also estimated the optimal concentration of rNDF using the first derivative of second order polynomials to be 13.3% for FBW, 13.0% for ADG, 12.8% for HCW, 13.7 and 11.3% for DMI when fed HMC and ground corn, respectively.…”

Aditivos (ionóforo e não ionóforo), processamento de grãos de milho e concentrações de fibra insolúvel em detergente neutro (FDN) de silagem de milho em dietas para bovinos em terminação

“…Entretanto, pequenas quantidades de forragem são incluídas na grande maioria das dietas de confinamento por duas razões principais: a) minimizar os riscos de acidose; b) estimular o consumo dos animais DEFOOR, 2003;WARE, 2004;VASCONCELOS, 2008;HUBBERT, 2012;CAETANO et al, 2015). A variação no nível de fibra insolúvel em detergente neutro (FDN) de forragem na dieta explica a maior parte da variação no consumo de matéria seca de bovinos confinados com dietas com baixo teor de forragem.…”

“…A inclusão de forragem em dietas com altos teores de concentrado estimula a ingestão de matéria seca (IMS), o consumo de energia e o ganho de peso dos animais, mas normalmente compromete a eficiência alimentar. A literatura é carente de trabalhos conduzidos nas condições tropicais sobre níveis de forragem nas dietas de terminação para animais zebuínos (CAETANO et al, 2015;MARQUES et al, 2016) Para que os produtores rurais produzam cada vez mais de forma sustentável, cientistas do mundo todo têm trabalhado de forma intensa para o desenvolvimento Figura 1 -Relação entre vitreosidade do grão de milho e a disponibilidade ruminal do amido analisados em híbridos dentados norte-americanos (■) e milho brasileiro do tipo flint (▲) Fonte: Adaptado de Correa et al (2002) …”

“…Caetano et al (2015) relataram que para otimizar a ingestão de energia de tourinhos da raça Nelore confinados com dietas ricas em milho moído fino ou ensilado úmido foi necessário incluir ao redor 13% de FDN de silagem de cana-de-açúcar na dieta. Melo (2015) reportou que a inclusão de 7% de FDN de bagaço de cana-de-açúcar (4, 7 10 ou 13% da MS da dieta) na dieta de tourinhos da raça Nelore foi suficiente para otimizar a ingestão de MS independente do processamento do milho (moagem grosseira ou floculação) mas não alterou a ingestão de energia dos animais.…”