Impacts of adding functional oils or sodium monensin in high-concentrate diets on performance, feeding behaviour and rumen morphometrics of finishing Nellore cattle

Abstract

This study, conducted at the São Paulo State University feedlot, Dracena campus, Brazil, was designed as a completely randomized block with 2 × 2 factorial arrangement of treatments to evaluate the effects of adding functional oils (FO) or sodium monensin (MON) on feedlot performance, carcass traits, feeding behaviour and rumen morphometrics of Nellore cattle. Ninety-six 20-mo-old Nellore bulls (365.52 ± 39.19 kg) were randomly allocated to 24 pens (n = 4/pen), which were assigned to the treatments: (1) Control (no feed additives); (2) FO (500 ppm); (3) MON (27 ppm); and (4) MON + FO (27 + 500 ppm, respectively). Each treatment was replicated 6 times, and cattle were fed for 105 days. From 0 to 28 days on feed, cattle fed FO had lower dry matter intake (DMI) variation, sorted for medium particles and presented smaller papillae width. The feeding of FO did not negatively impact feedlot performance overall. When MON was added to the diet, cattle had lower DMI overall and 12th rib fat daily gain, and improved gain to feed ratio. The addition of MON to diets improved feedlot performance but reduced the rate of carcass fat deposition. The few effects observed when FO was added to diets were not sufficient to impact feedlot performance.

The Potential of Shortening the Adaptation of Nellore Cattle to High-Concentrate Diets Using Only Virginiamycin as Sole Feed Additive

“…In fact, the cattle fed VM14 had an increased DMI, as percent of BW, by 4.7% when compared to the cattle consuming MON14 ( Table 5 ), which may have contributed to greater fat deposition due to the increased amount of energy consumed throughout the study since no differences were observed for starch digestibility during adaptation or finishing ( Table 7 ). This negative effect of MON on carcass fat deposition, as shown in this study, has been reported previously by other authors ( 33 ), and it is potentially related to the decreasing molar proportion of ruminal acetate ( 34 ). Therefore, the impaired feed efficiency presented by the cattle fed VM14 may be partially attributed to more extensive fat deposition, which requires more energy or calories per gram of tissue than muscle accretion ( 35 , 36 ).…”

Nutrient Requirements of Zebu and Crossbred Cattle - BR-CORTE

“…In contrast, Rigueiro et al (2020), evaluating feedlot performance of Nellore bulls receiving different combinations of virginiamycin (25 mg/kg of DM) and monensin (30 mg/kg of DM) during the adaptation and finishing periods, observed an improvement in overall productive performance when bulls were fed the additive combination only during the adaptation period; with no benefits when the combination was supplemented during the finishing period or the entire feeding period (adaptation and finishing). The authors postulated that their results reflected the absence of the negative impact of monensin on DMI, since bulls were supplemented with ionophore for the shortest period.…”

“…Proper management of this phase may influence intake and performance throughout the feedlot period. According to Estevam et al (2020), one of the determining factors for the adaptation protocol is the energy content of finishing diets. According to these authors, systems that use less energy in the diets can reduce the adaptation periods without health problems and performance reduction.…”

“…Monensin generally depresses feed intake with a little or no effect on ADG. FE is improved when diets containing high levels of readily fermentable carbohydrates are fed to cattle Duffield et al, 2012;Melo et al, 2020). In diets with greater forage content or in grazing systems, monensin does not decrease intake, and ADG is usually improved, resulting in improved FE (Bretschneider et al, 2008;Maciel et al, 2019;Gadberry et al, 2022a).…”

“…However, the effects of feed additives reported have not always been consistent. For example, reduced dry matter intake (DMI) and improved feed efficiency (FE), with either no effect or an increase in average daily gain (ADG), have been observed in feedlot cattle fed monensin (Raun et al, 1976;Melo et al, 2020), whereas some studies have not found significant effects on DMI and FE for cattle in either feedlot or pasture production systems (McGinn et al, 2004;Maciel et al, 2019).…”