The evolution of ruminants was largely influenced by the symbiotic relationship between ruminal microbiota and the host. Within the rumen, these microorganisms degrade feedstuffs to produce organic ...acids and synthesize microbial protein, as energy and protein source for ruminants, respectively. This process is accelerated when these animals are transferred to feedlot diets. This review brings the most current studies that reported the most used nutritional managements in this transition process, in order to avoid metabolic disturbances, in which rumen development is a fundamental point. Also, this review brings the main biomolecules used as feed additive, which can in the help control of fermentation processes in order to minimize energetically inefficient processes within the rumen, as well as losses by excretion to the environment, which are widely questioned by be environmental pollutants. Furthermore, the main results of research on animal performance in response to these additives are reported, supplemented alone or associated with different feed additives when used on diets with high grain contents, as well as evaluating the potential of additives as antibiotics alternatives, a fact that has been discussed and is worrying since the use of ionophores or non-ionophores antibiotics represent practically the totality of feedlot diets.
Feed additives such as monensin (MON) and virginiamycin (VM) are commonly utilized in feedlot diets to enhance rumen fermentation. Nevertheless, the precise effects of combining MON and VM during ...specific feedlot periods and the advantages of this combination remain unclear. This study was designed to investigate the effects of withdrawal of MON when associated with VM during the adaptation and finishing periods on ruminal metabolism, feeding behavior, and nutrient digestibility in Nellore cattle. The experimental design was a 5 × 5 Latin square, where each period lasted 28 days. Five rumen-cannulated Nellore yearling bulls were used (414,86 ± 21,71 kg of body weight), which were assigned to five treatments: (1) MON during the entire feeding period; (2) VM during the entire feeding period; (3) MON + VM during the adaptation period and only VM during the finishing period 1 and 2; (4) MON + VM during the entire feeding period; (5) MON + VM during the adaptation and finishing period 1 and only VM during the finishing period 2. For the finishing period 1, animals fed T3 had improved potential degradability of dry matter (
= 0.02). Cattle fed T3 and T5 had the highest crude protein degradability when compared to animals receiving T2 (
= 0.01). Animals fed T2 and T3 had reduced the time (
< 0.01) and area under pH 6.2 (
= 0.02). Moreover, animals fed T4 had greater population of protozoa from the genus
(
= 0.04) when compared to those from animals fed T2, T3 and T5. For the finishing period 2, animals fed T3 had greater starch degradability when compared to animals receiving T4 and T5 (
= 0.04). Animals fed T3, T4 and T5 had increased the duration of time in which pH was below 5.6 (
= 0.03). The area under the curve for ruminal pH 5.2 and pH 5.6 was higher for the animals fed T3 (
= 0.01), and the area under pH 6.2 was higher for the animals fed T3 and T5 (
< 0.01) when compared to animals receiving T2. There is no substantial improvement on the rumen fermentation parameters by the concurrent utilization of MON and VM molecules, where the higher starch and protein degradability did not improve the rumen fermentation.
Feedlot cattle are usually adapted to high-concentrate diets containing sodium monensin (MON) in more than 14 days. However, considering that the dry matter intake DMI is usually lower during ...adaptation when compared to the finishing period, the use of MON during adaptation may decrease even further the DMI, and virginiamycin (VM) may be an alternative. This study was designed to investigate the effects of shortening the adaptation length from 14 to 9 or 6 days on ruminal metabolism, feeding behavior, and nutrient digestibility of Nellore cattle fed high-concentrate diets containing only VM as the sole feed additive. The experimental design was a 5 × 5 Latin square, where each period lasted 21 days. Five 17 mo-old Nellore yearling bulls were used (415 ± 22 kg of body weight), which were assigned to five treatments: (1) MON (30 mg/kg) and adaptation for 14 days; (2) MON (30 mg/kg) + VM (25 mg/kg) and adaptation for 14 days; (3) VM (25 mg/kg) and adaptation for 14 days; (4) VM (25 mg/kg) and adaptation for 9 days, and (5) VM (25 mg/kg) and adaptation for 6 days. A quadratic effect for adaptation length when only VM was fed was observed for mean pH (
= 0.03), duration of pH below 5.2 (
= 0.01) and 6.2 (
= 0.01), where cattle consuming VM adapted for 9 days had higher mean pH and shorter period of pH below 5.2 and 6.2. Cattle that consumed only MON had a lower concentration of butyrate (
= 0.02) and a higher concentration of propionate (
= 0.04) when compared to those consuming VM and adapted for 14 days. As the adaptation length decreased for animals consuming only VM, the rumen degradability of dry matter (
< 0.01), neutral detergent fiber (
< 0.01), and starch (
< 0.01) decreased; however, protozoa numbers of
and total protozoa increased. It is not recommended to shorten the adaptation length of these animals to either 6 or 9 days without negatively impacting nutrient disappearance and ruminal fermentation patterns.
Feed additives such as monensin (MON) and virginiamycin (VM) are widely used in feedlots diets to maximize rumen fermentation. However, the knowledge about the effects of MON and VM combinations in ...specifics feedlot periods and the benefits of this association are still unclear. This study aimed to evaluate the effects of withdrawal of MON when associated with VM during the adaptation and finishing periods on feedlot performance of Nellore cattle. The experiment was designed as a completely randomized block replicated six times (four animals/pen) in which 120 Nellore bulls (378.4 ± 24.4 kg) were allocated in 30 pens and fed for 112 days according to the following treatments: (T1) MON during the entire feeding period; (T2) VM during the entire feeding period; (T3) MON+VM during the adaptation period and only VM during the finishing period 1 and 2; (T4) MON+VM during the entire feeding period; (T5) MON+VM during the adaptation and finishing period 1 and only VM during the finishing period 2. After 112 days on feed, no treatment effect was observed for DMI (
≥ 0.12). However, bulls fed T5 had greater (
= 0.05) final BW and ADG when compared to T1, T2, and T4. Cattle from T3 and T5 groups presented heavier HCW (
= 0.05) than that fed T1, T2, and T4. Nellore bulls fed T1 and T5 had lower (
< 0.01) DMI variation than those receiving T2. The withdrawal of MON when associated with VM during the final third of the feedlot period improved overall final BW, ADG, and HCW when compared to bulls fed either MON or VM, but did not positively impact feedlot performance when compared to cattle that had MON withdrawn at the end of the adaptation period.
There may be an increased risk of metabolic disorders, such as rumen acidosis, in cattle fed high‐concentrate diets, particularly those from Bos taurus indicus genotypes, which have shown to be more ...sensitive to ruminal acidification. Therefore, this study aimed to estimate (co)variance components and identify genomic regions and pathways associated with ruminal acidosis in feedlot Nellore cattle fed high‐concentrate diets. It was utilized a dataset containing a total of 642 Nellore bulls that were genotyped from seven feedlot nutrition studies. The GGP Indicus 35k panel was used with the single step genome‐wide association study methodology in which the effects of the markers were obtained from the genomic values estimated by the GBLUP model. A bivariate model to estimate genetic correlations between the economically important traits and indicator traits for acidosis was used. The traits evaluated in this study that were nutritionally related to rumen acidosis included average daily gain (ADG), final body weight, time spent eating (TSE), time spent ruminating, rumenitis score (RUM), rumen absorptive surface area (ASA), rumen keratinized layer thickness (KER) and hot carcass weight (HCW). The identified candidate genes were mainly involved in the negative or non‐regulation of the apoptotic process, salivary secretion, and transmembrane transport. The genetic correlation between HCW and ASA was low positive (0.27 ± 0.23), and between ADG and ASA was high moderate (0.58 ± 0.59). A positive genetic correlation between RUM and all performance traits was observed, and TSE correlated negatively with HCW (−0.33 ± 0.21), ASA (−0.75 ± 0.48), and KER (−0.40 ± 0.27). The genetic association between economically important traits and indicator traits for acidosis suggested that Nellore cattle may be more sensitive to acidosis in feedlot systems.
This study was designed to evaluate a spray-dried multivalent polyclonal antibody preparation (PAP) against lactate-producing bacteria as an alternative to monensin (MON) to control ruminal ...acidification. Holstein cows (677 ± 98 kg) fitted with ruminal cannulas were allocated in an incomplete Latin square design with two 20 days period. Cows were randomly assigned to control (CTL), PAP, or MON treatments. For each period, cows were fed a forage diet in the first 5 days (d-5 to d-1), composed of sugarcane, urea and a mineral supplement, followed by a 74% concentrate diet for 15 days (d 0 to d 14). There were no treatment main effects (
> 0.05) on dry matter intake (DMI) and microbial protein synthesis. However, there was a large peak (
< 0.01) of intake on d 0 (18.29 kg), followed by a large decline on d 1 (3.67 kg). From d2, DMI showed an increasing pattern (8.34 kg) and stabilized around d 8 (12.96 kg). Higher mean pH was measured (
< 0.01) in cattle-fed MON (6.06 vs. PA
= 5.89 and CTL = 5.91). The ruminal NH
-N concentration of CTL-fed cows was lower (
< 0.01) compared to those fed MON or PAP. The molar concentration of acetate and lactate was not affected (
> 0.23) by treatments, but feeding MON increased (
= 0.01) propionate during the first 4 days after the challenge. Feeding MON and PAP reduced (
= 0.01) the molar proportion of butyrate. MON was effective in controlling pH and improved ruminal fermentation of acidosis-induced cows. However, PAP was not effective in controlling acidosis. The acidosis induced by the challenge was caused by the accumulation of SCFAs. Therefore, the real conditions for evaluation of this feed additive were not reached in this experiment, since this PAP was proposed to work against lactate-producing bacteria.
Feed additives used in finishing diets improve energy efficiency in ruminal fermentation, resulting in increased animal performance. However, there is no report evaluating the effect of BEO ...associated with exogenous α-amylase in response to increased starch content in feedlot diets. Our objective was to evaluate increasing levels of starch in the diet associated with a blend of essential oils plus amylase or sodium Monensin on performance, carcass characteristics, and ruminal and cecal morphometry of feedlot cattle. 210 Nellore bulls were used (initial body weight of 375 ± 13.25), where they were blocked and randomly allocated in 30 pens. The experiment was designed in completely randomized blocks in a 3 × 2 factorial arrangement: three starch levels (25, 35, and 45%), and two additives: a blend of essential oils plus α-amylase (BEO, 90 and 560 mg/kg of DM, respectively) or sodium Monensin (MON, 26 mg/kg DM). The animals were fed once a day at 08:00
and underwent an adaptation period of 14 days. The diets consisted of sugarcane bagasse, ground corn, soybean hulls, cottonseed, soybean meal, mineral-vitamin core, and additives. The animals fed BEO35 had higher dry matter intake (
= 0.02) and daily weight gain (
= 0.02). The MON treatment improved feed efficiency (
= 0.02). The treatments BEO35 and BEO45 increased hot carcass weight (
< 0.01). Animals fed BEO presented greater carcass yield (
= 0.01), carcass gain (
< 0.01), rib eye area gain (
= 0.01), and final rib eye area (
= 0.02) when compared to MON. The MON25 treatment improved carcass gain efficiency (
= 0.01), final marbling (
= 0.04), and final subcutaneous fat thickness (
< 0.01). The use of MON reduced the fecal starch% (
< 0.01). Cattle-fed BEO increased rumen absorptive surface area (
= 0.05) and % ASA papilla area (
< 0.01). The MON treatment reduced the cecum lesions score (
= 0.02). Therefore, the use of BEO with 35 and 45% starch increases carcass production with similar biological efficiency as MON; and animals consuming MON25 improve feed efficiency and reduce lesions in the rumen and cecum.
We aimed to evaluate the effect of supplementation with sunflower seed on blood concentrations of progesterone and cholesterol and on the pregnancy rate in beef cattle subjected to timed artificial ...insemination (TAI) and timed embryo transfer (TET). In experiment 1, cows were received 22-day supplements containing (sunflower, n = 66) sunflower seed or not (control, n = 67) immediately after a progesterone/estradiol–based TAI protocol (Day 0). The cholesterol concentration on Day 21 and the pregnancy rate were greater (P < 0.03) in the sunflower group (148.2 ± 6.1 mg/dL and 66.7%) than those in the control group (116.0 ± 6.4 mg/dL and 47.8%). In experiment 2, heifers received an in vitro–produced embryo 7 days after the expected time of the synchronized ovulation. Heifers were separated into two supplementation groups (sunflower, n = 106 and control, n = 111) for 22 days. The plasma progesterone concentration on Day 7 was not different between the groups. However, on Day 19, the plasma progesterone concentration was greater (P < 0.0001) in the sunflower group (5.8 ± 0.4 ng/mL) than that in the control group (3.5 ± 0.4 ng/mL). A greater (P < 0.05) cholesterol concentration was observed in the sunflower group than that in the control group on Days 7 (306.0 ± 11.6 vs. 277.1 ± 11.9 mg/dL, respectively) and 19 (260.5 ± 8.0 vs. 232.0 ± 8.0 mg/dL, respectively). The pregnancy rate was greater (P = 0.01) in the sunflower-treated heifers (55.7%) than that in control-treated heifers (36.9%). Results indicate that sunflower seed supplementation increases the circulating cholesterol concentrations and potentially impacts the pregnancy rate in suckled beef cattle subjected to TAI or TET.
Sugarcane silage (SS) is generally susceptible to yeast action, resulting in dry matter losses due to high soluble carbohydrate concentration. We evaluated the effects of adding corn grain and ...microbial inoculant at ensiling on fermentative profile, losses, chemical composition and degradation of silages. Forty experimental silos (PVC tubing) were assigned at random to a 5 × 2 factorial arrangement with: (1) 5 corn additions at ensiling: CONT - straight sugarcane silage; GC2 - sugarcane with ground corn (processed through a 2 mm sieve) added at ensiling; GC8 - sugarcane with ground corn (processed through an 8 mm sieve) added at ensiling; WC - sugarcane with whole corn grain added at ensiling; and RCS - rehydrated corn ensiled without sugarcane; and (2) 2 microbial inoculant additions at ensiling: 0 and 8 mg of commercial inoculant per kg of feed. Corn grain was added at the rate of 100 g per kg of fresh sugarcane. Adding corn grain to sugarcane at ensiling improved SS fermentation and silage chemical composition. There was no benefit from grinding the grain before adding it to sugarcane. Microbial inoculant had little effect on SS fermentation. Studies comparing corn grain with other energy sources, e.g. molasses or cassava, for addition at ensiling sugarcane seem warranted along with feeding studies with livestock to assess intake and subsequent performance. The overall benefits of adding the energy sources at ensiling versus feeding them directly to animals with untreated sugarcane silage should be determined.
•Fecal recovery was variable throughout the day and dependent on internal maker used.•Indigestible DM, NDF, and ADF had partial fecal recovery.•Fat supplementation affected fecal output and ...digestibility estimation using different markers.•The lowest concentration of markers occurred one hour after the morning feeding.•The highest concentration of marker was observed between 15:00 and 24:00 h.
We aimed to evaluate the effects of sampling time points on fecal contents of indigestible DM, NDF, and ADF, fecal recovery, and apparent digestibility in cows fed different levels of rumen degradable protein (RDP) without or with supplementation of calcium salts of fatty acids (CSFA). Eight multiparous Holstein cows (207 ± 23.6 days in milk, 618 ± 39.0 kg body weight; mean ± SD) were randomly allocated into a 4 × 4 Latin square design with 21 days of experimental period. A 2 × 2 factorial treatment arrangement was used in this study to evaluate the effects of calcium salts of fatty acids CSFA: -CS, basal diet without fat supplementation; and +CS, with 33.2 g CSFA/kg DM and rumen degradable protein (RDP) levels LP: low RDP, 98.0 g/kg DM; and HP: high RDP, 110 g/kg DM. Cows were fed twice daily, and total collection of feces was carried out for 72 h (from D15 8:00 to D18 8:00 h). In addition, spot samples were collected every nine hours, from D15 09:00 until D18 00:00 h. Samples of each sampling time were analyzed for iDM, iNDF, and iADF content. Internal markers showed a partial fecal recovery and, consequently, overestimated fecal excretion, and underestimated total-tract apparent digestibility. Indigestible NDF showed lower fecal recovery than iADF (855 vs. 935 g/kg). An interaction effect between marker and CSFA was observed for marker recovery where fat supplementation had greater influence on iADF recovery compared with iDM recovery. In addition, the fecal concentration of internal markers was affected by sampling time where the lowest concentrations of iDM were observed at 9:00 and the highest concentrations were detected between 15:00 and 00:00. Thus, experimental procedures need to consider diurnal variation of internal markers excretion. Internal markers, especially iDM, show partial fecal recovery.
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