Rumen Morphometrics Research Articles

Dried distiller’s grains in the diets of feedlot lambs: implications for production, carcass characteristics and rumen morphometrics

Context The demand and production of renewable fuels are boosting the production of biofuels. Agricultural industries have been playing a role in the increase of ethanol production from corn and, consequently, their by-products. Dried distiller’s grain (DDG) is a by-product of corn ethanol and can be used as a source of protein and energy in the diet of feedlot lambs. Aims The objectives of this experiment were to evaluate the effects of including DDG in high-concentrate diets on performance, rumen morpho-histology, and carcass characteristics in feedlot lambs. Methods Forty-five Santa Inês × Dorper male lambs with an initial body weight of 21 ± 3.2 kg (mean ± s.d.) and 82 ± 12 days old (mean ± s.d.) were distributed in a randomised complete-block design (nine blocks and five treatments). The experimental diets contained 900 g/kg of concentrate and 100 g/kg of coastcross hay, and DDG was used in replacement of soybean meal and corn. Lambs were fed one of the following five diets for 112 days: control without DDG (0DDG), or diet with 150 (150DDG), 300 (300DDG), 450 (450DDG) and 600 (600DDG) g/kg DM of DDG. Key results The inclusion of DDG from 150 up to 600 g/kg DM in the diet of the lambs linearly decreased (P < 0.01) dry-matter intake (DMI), net energy of maintenance intake, net energy of gain, average daily gain, final body weight and feed efficiency (P < 0.01). The inclusion of DDG linearly decreased (P ≤ 0.04) hot carcass weight, cold carcass weight, hot carcass yield and cold carcass yield. For ruminal morpho-histology, there was a linear decrease in the area of papillae and absorptive surface area (P < 0.01) Conclusions An increase in the DDG level from 150 to 600 g/kg DM in the diet of lambs negatively affected feedlot performance, with detrimental effects on carcass traits and the development of rumen papillae. The lambs showed low acceptance of DDG, even at the lowest level of dietary inclusion (150g/kg DM) as DMI was impaired. Implications DDG should be used with caution in diets for finishing lambs. Dietary inclusion of DDG up to 150 g/kg DM is recommended. Higher inclusions levels may significantly affect performance and carcass weight and yield.

Effects of monensin and a blend of magnesium oxide on performance, feeding behavior, and rumen morphometrics of Zebu beef cattle fed high-starch diets

Abstract This study aimed to evaluate the effects of a blend of different sources of magnesium oxide associated or not with monensin, on productive, ruminal, and nutritional parameters of steers. Eighty-four Nellore steers with an initial body weight (BW) of 367.3 ± 37.9 kg were allocated to one of 28 pens, with three steers per pen. Each pen was considered an experimental unit, and using a completely randomized design with a 2 × 2 factorial arrangement, the following treatments were assigned to each pen: (1) Control (CON) – a basal diet without additive inclusion; (2) Magnesium oxide blend (MG) – basal diet plus a magnesium-based product (pHix-up®, Timab Magnesium, Dinard, France) provided at 0.50% of dry matter (DM); (3) Monensin (MON) – basal diet plus 25 mg/ kg of DM of sodium monensin (Rumensin, Elanco Animal Health, Greenfield, IN); and (4) MG association with MON – basal diet plus MG + MON, at the same doses of the individual treatments. The experimental period lasted 100 days. Blood samples were collected on days 0, 13, and 70 to determine D-lactate levels. Daily feed intake was recorded, and animal ingestive behavior was visually observed on days 66 and 67. On day 70, skeletal muscle tissue samples were obtained through biopsy for gene expression analysis. At the end of the experimental period, carcass ultrasonography was conducted. Subsequently, the steers were slaughtered, and rumen epithelium samples were collected for morphometric analysis. The use of monensin, of magnesium oxide blend, and their interactions, were treated as fixed effects, while the pens were considered as a random effect. Statistical differences were considered when P < 0.05. Steers fed MG-containing diets consumed approximately 0.6 kg more dry matter per day than those fed diets without this additive (P = 0.01; 11.3 vs. 11.9 kg/day). The inclusion of MG in the diet increased (P = 0.02) the average daily gain (ADG). There was a greater Longissimus muscle area (LMA) and LMA per 100 kg of body weight (BW) (P ≤ 0.03) for steers-fed diets with MG. Steers fed MON exhibited reduced mRNA expression of the Atrogin-1 and mTOR compared to steers fed MG + MON diets (MON × MG: P ≤ 0.04). Steers fed MON had 6.9% greater feed efficiency (P = 0.02). Papillae width was lesser for CON than other treatments (MON × MG: P = 0.02). In conclusion, the magnesium oxide blend improved performance and carcass traits in high-energy feedlot diets, while monensin enhanced feed efficiency, suggesting potential for their use as alternatives or complements in beef cattle nutrition.

Effects of a Bacillus-based direct-fed microbial on performance, blood parameters, fecal characteristics, rumen morphometrics, and intestinal gene expression in finishing beef bulls.

We evaluated the effects of supplementing direct-fed microbials (DFM), containing Bacillus licheniformis and Bacillus subtilis, on performance, rumen morphometrics, intestinal gene expression, and blood and fecal parameters in finishing bulls. Nellore × Angus bulls (n = 144; initial BW = 401 ± 45.5kg) were distributed at random in 36 pens (4 bulls/pen and 18 pens/treatment), following a completely randomized design. A ground corn-based finishing diet was offered for ad libitum intake twice a day for 84 d, containing the following treatments: 1) control (without DFM); 2) DFM (B. licheniformis and B. subtilis) at 6.4 × 109 CFU (2g) per animal. The data were analyzed using the MIXED procedure of SAS, with a pen representing an experimental unit, the fixed effect of the treatment, and the random effect of pen nested within the treatment. For fecal parameters (two collections made), the collection effect and its interaction with the treatment were included in the model. Bulls that received the DFM had a decreased dry matter intake (P ≤ 0.01), did not differ in average daily gain (2.05kg; P = 0.39), and had a 6% improvement in gain:feed (P = 0.05). The other performance variables, final BW, hot carcass weight, and hot carcass yield, did not differ (P > 0.10). Plasma urea-N concentration decreased by 6.2% (P = 0.02) in the bulls that received DFM. Glucose, haptoglobin, and lipopolysaccharides were not different between treatments (P > 0.10). Ruminal morphometrics were not affected by the treatment (P > 0.10). The use of DFM tended to reduce fecal starch (P = 0.10). At slaughter, bulls fed DFM had an increased duodenal gene expression of tryptophan hydroxylase-1 (P = 0.02) and of superoxide dismutase-1 (P = 0.03). Overall, supplementation with DFM based on B. licheniformis and B. subtilis to Nellore × Angus bulls in the finishing phase decreased dry matter intake, did not influence ADG, improved gain:feed, and increased the expression of genes important for duodenal function.

Encapsulated Butyric Acid and Zinc as a Feed Additive for Lambs Abruptly Transitioned to a Grain-Based Diet.

Butyric acid is attributed to gastrointestinal epithelial development and health and two studies were conducted to determine if supplementing encapsulated butyric acid and zinc (BZ) in lambs abruptly transitioned to a finishing diet has effects on growth performance, efficiency of dietary net energy utilization, rumen morphometrics, small intestinal histology, and carcass traits. Polypay wethers (n = 84; initial shrunk body weight = 38.8 kg ± 4.8 kg) were used in a randomized complete block design study. Wethers were abruptly transitioned from a high roughage-based diet to a 100% concentrate-based diet and dietary treatments were 0 or 2 g BZ/kg of diet dry matter. Study 1 evaluated growth performance and carcass traits of lambs over a 59.5 d feeding period, and Study 2 evaluated changes in rumen morphometrics and small intestine histology in serial harvested lambs. Wethers supplemented with BZ had increased body wall thickness, decreased calculated boneless closely trimmed retail cuts, and decreased red meat yield (p ≤ 0.03) compared to non-supplemented wethers. Linear effects (p ≤ 0.01) for harvest date were observed for most rumen and small intestine measurements. Supplementing wethers with BZ did not improve growth performance, carcass traits, or rumen and small intestine measurements. The effects of BZ supplementation on fat deposition in ruminants should be further investigated.

Dose effects of encapsulated butyric acid and zinc on beef feedlot steer growth performance, dietary net energy utilization, rumen morphometrics, small intestine histology, and carcass characteristics.

The objective of this study was to determine the effects that increasing doses of encapsulated butyric acid and zinc (BZ) have on feedlot steer growth performance, rumen morphometrics and small intestine histology (data not statistically analyzed), dietary net energy utilization, and carcass characteristics. Steers [n = 272; shrunk body weight (BW) = 360 kg ± 74 kg] were assigned to dietary treatments [0 (CON), 1, 2, or 3g BZ/kg diet dry matter] in a randomized complete block design (RCBD) with pen (n = 32 total; n = 8 per treatment) as experimental unit. Pens were blocked by cattle source and location within the feedyard. Cattle were fed until visually assessed to have 1.27cm rib-fat and were shipped for harvest at a commercial beef abattoir. Carcass and liver health data were recorded. A subset of steers (n = 8 total; n = 2 per treatment) was harvested at the SDSU Meat Laboratory to collect empty body measurements, rumen samples for morphometric analysis, and duodenal and ileal samples for histological analysis to provide context to feeding trial outcomes. Feedlot growth performance data was calculated on a carcass-adjusted basis: hot carcass weight (HCW)/0.625. Data were analyzed as a RCBD with fixed effects of BZ inclusion level and block was considered a random effect; pre-planned contrasts for CON vs. BZ, plus linear, and quadratic responses were tested. No differences (P ≥ 0.11) were observed for final BW, dry matter intake, average daily gain (ADG), feed conversion efficiency (G:F), performance calculated dietary net energy, HCW, ribeye area, rib-fat thickness, marbling score, estimated empty body fat, or distribution of USDA yield grade (YG) 1, 3, 4, 5, and USDA quality grade among treatments. A tendency (P = 0.10) was observed for CON vs. BZ for calculated YG. Tendencies were detected for USDA YG 2 carcass distribution (linear; P = 0.07) and for normal and abscessed liver prevalence (quadratic; P = 0.08). Dressed yield tended to be greater (P = 0.08) for BZ vs. CON and increased with dose (linear; P = 0.05). Receiving period shrunk BW, ADG, and G:F was improved (P ≤ 0.02) for BZ-supplemented steers compared to CON. Data from this study suggests that the addition of BZ to feedlot finishing diets to improve receiving period growth performance and decreasing the prevalence of abscessed livers should be further investigated.

Essential oil from Arnica montana on feedlot performance, ingestive behavior, carcass characteristics, rumen morphometrics characteristics and meat fatty acids profile of lambs

This study aimed to evaluate the effects of Essential oil (EO) from Arnica montana as a feed additive on feedlot performance, ingestive behavior, carcass characteristics, rumen morphometrics characteristics and meat fatty acids profile of lambs. Forty Dorper × Santa Inês male lambs with 30.3 ± 5.76 kg (mean ± standard deviation) of initial body weight and 92 ± 9 days (mean ± standard deviation) of age were used. The experimental design was in a randomized complete block (5 treatments and 8 blocks). Lambs were fed a basal diet (160 ± 13 g/kg DM of CP; mean ± standard deviation) containing 90 % concentrate and 10 % forage (Coastcross hay). The experimental diets were: A0 - negative control (basal diet without additive); A450 - addition of 450 mg/kg DM of EO from Arnica montana; A900 - addition of 900 mg/kg DM of EO from Arnica montana; A1350 - addition of 1350 mg/kg DM of EO from Arnica montana; M25 - positive control (basal diet containing 25 mg/kg DM of sodium monensin). Increasing EO from Arnica montana content conferred a quadratic effect on dry matter intake (DMI) (P = 0.02), with higher DM in A450. The DMI was higher (P < 0.01) in diets with EO from Arnica montana compared to M25. The average daily gain (ADG), body weight at slaughter (BWS), hot and cold carcass weight (HCW and CCW) increased linearly with increasing EO from Arnica montana (P < 0.05). The lambs had higher ADG, BWS, HCW and CCW with EO from Arnica montana than M25 (P < 0.05). The oocyst/g feces decreased linearly (P < 0.0001) with increasing EO from Arnica montana in the diet. However, the M25 was more efficient in reducing the oocyst than the other treatments (P < 0.05). The number of meals and time spent feeding increased linearly (P < 0.05) with the increase of EO from Arnica montana. There was a quadratic effect (P < 0.05) on feeding rate (min/g DM), with the lowest rate in A450. Time spent ruminating (min/day) was affected quadratically (P = 0.01) by increasing EO from Arnica montana, this activity was higher in A900. Compared to M25, time spent ruminating and total chewing time were longer (P < 0.05) and the feeding rate and chewing rate (min/g of NDF) were lower (P < 0.05) in diets with EO from Arnica montana. The higher inclusion of EO from Arnica montana decreased linearly the C17:0; C18:0; C18:1 trans-11, C22:6 n3 and the sum of saturated fatty acids (ΣSFA), and linearly increased the C18: 2 cis-9, cis-12; C18:3 cis-9, cis-12, cis-15, the sum of polyunsaturated (ΣPUFA) and the sum of n6 (P < 0.05). Diets with EO from Arnica montana decreased the C16:0, C17:0, C18:0 and increased the C18:2 cis-9, cis-12, ΣSFA, Σn6 and the n6/n3 ratio (P < 0.05) compared to M25. Sodium monensin at a dose of 25 mg/kg DM can be replaced by EO from Arnica montana in high-concentrate diets to promote lamb performance, carcass characteristics and fatty acid profile in the meat. The use of 1350 mg/kg DM of EO from Arnica montana was the best dose in high-concentrate diets in feedlot lambs, due to positive effect on performance, carcass characteristics, and the fatty acid profile of the meat.

Relationships of the Microbial Communities with Rumen Epithelium Development of Nellore Cattle Finished in Feedlot Differing in Phenotypic Residual Feed Intake.

Simple SummarySeveral data have been published in the literature on the feed efficiency of cattle, measured through residual feed intake, in which the focus is to reduce production costs and improve cattle producer’s profit margins. Most of this variation in animal intake has been attributed to changes in animal metabolism, such as the rate of short-chain fatty acids absorption by the rumen epithelium, hepatic and mitochondrial metabolism, feeding behavior, and content of empty body fat. All these factors impact the anabolism/catabolism of substrates reaching the blood system. However, studies evaluating the composition of the rumen microbial community of animals differing in residual feed intake are scarce, and, therefore, this study aimed to compare the ruminal microbial communities, rumen morphometrics, feeding behavior, feedlot performance, and carcass characteristics of Nellore cattle, ranked by residual feed intake. Our results suggest that ruminal microbial community was not affected across different groups of residual feed intake, suggesting that differences in the efficiency of Nellore animals are associated with other factors.The objective of this study was to examine the relationships among ruminal microbial community, rumen morphometrics, feeding behavior, feedlot performance, and carcass characteristics of Nellore cattle, classified by residual feed intake (RFI). Twenty-seven Nellore yearling bulls with an initial body weight (BW) of 423.84 ± 21.81 kg were fed in feedlot for 107 d in individual pens to determine the RFI phenotype. Bulls were categorized as high RFI (>0.5 SD above the mean, n = 8), medium RFI (±0.5 SD from the mean, n = 9), and low RFI (<0.5 SD below the mean, n = 10). At harvest, whole rumen content samples were collected from each bull to evaluate ruminal microbial community, including bacteria and protozoa. The carcass characteristics were determined by ultrasonography at the beginning and at the end of the experimental period, and behavior data were collected on d 88. As a result of ranking Nellore bulls by RFI, cattle from low-RFI group presented lesser daily dry matter intake (DMI), either in kilograms (p < 0.01) or as percentage of BW (p < 0.01) than high-RFI yearling bulls, resulting in improved gain:feed (G:F). However, variables, such as average daily gain (ADG), final BW, hot carcass weight (HCW) and other carcass characteristics did not differ (p > 0.05) across RFI groups. The eating rate of either dry matter (DM )(p = 0.04) or neutral detergent fiber (NDF) (p < 0.01) was slower in medium-RFI yearling bulls. For ruminal morphometrics an RFI effect was observed only on keratinized layer thickness, in which a thinner layer (p = 0.04) was observed in low-RFI Nellore yearling bulls. Likewise, Nellore yearling bulls classified by the RFI did not differ in terms of Shannon’s diversity (p = 0.57) and Chao richness (p = 0.98). Our results suggest that the differences in feed efficiency of Nellore bulls differing in phenotypic RFI should be attributed to metabolic variables other than ruminal microorganisms and epithelium, and deserves further investigation.

Voluntary daily fluctuation in dry matter intake is associated to feedlot performance, feeding behavior and rumen morphometrics in beef cattle

• Cattle from low-DMI fluctuation group improved feedlot performance. • High-DMI fluctuation pens took longer to eat and ruminate a kg of both DM and NDF. • High-DMI fluctuation negatively impacted blood gas profile and rumenitis scores. The degree of day-to-day fluctuation in voluntary DMI may influence feeding and rumination behavior, with potential impacts on feedlot performance. The purpose of this study was to evaluate the effect of voluntary fluctuation of DMI by pens of cattle given free-choice access to feed. These responses were measured in a dataset compiled from ten feedlot studies from 2006 to 2015. The data set included a total of 956 16-mo-old Bos indicus bulls (343.60 ± 44.15 kg) randomly allocated to a total of 238 pens (4 bulls per pen); cattle were fed high concentrate feedlot diets for an average of 106-d (minimum: 84-d; maximum: 140-d), and slaughtered at a commercial abattoir. To balance statistically for differences in animal background, type, and condition, for each year within treatments, pens were allocated into one of two groups: below or above the mean DMI fluctuation. The low- and the high- DMI fluctuation groups had day-to-day fluctuation in DMI of 5.18% and 6.22%, respectively ( P < 0.01) or 0.45 vs. 0.55 kg/day (P < 0.01). Data were analyzed using a generalized linear mixed model procedure with the statistical software R. Cattle within the low-DMI fluctuation group had 4.2% greater (1.48 vs. 1.42 kg/d; P < 0.01) ADG and 3.7% greater (2.26 vs. 2.18 kg/d; P < 0.001) DMI expressed as a percentage of mean BW; but no significant effect was detected for G:F ratio ( P = 0.91). Animals from the low-DMI fluctuation group had greater ( P ≤ 0.01) daily increase in LM area and 12 th rib fat as well as heavier HCW (266 vs. 263 kg; P = 0.04). Cattle from low-DMI fluctuation group consumed more DMI per meal ( P < 0.001) and had greater NDF intake ( P = 0.01) than cattle from the high-DMI fluctuation group. In addition, animals from high-DMI fluctuation pens took longer to consume and ruminate each kg of diet DM ( P < 0.01) and NDF ( P < 0.01) compared to cattle from low-DMI fluctuation group. A effect ( P = 0.04) was detected for blood base excess (BEB) with low-DMI fluctuation pens having a greater concentration of BEB. Moreover, the low-DMI fluctuation group tended to have ( P = 0.07) lower rumenitis scores. Although causal effects cannot be differentiated from casual relationships in this study, the fact that reduced daily DMI fluctuation was related to greater ADG and carcass weight makes this measurement relevant as an index of performance, and efforts to reduce DMI variability are warranted. Reducing day-to-day fluctuations in DMI should improve cattle health and performance.

Influence of Cane Molasses Inclusion to Dairy Cow Diets during the Transition Period on Rumen Epithelial Development.

Simple SummaryThe rumen epithelium of dairy cattle undergoes a transformation in response to dietary and physiological changes. Rumen papillae development and adaptation from a typical dry cow diet to a lactating diet can require a substantial amount of time, subsequently limiting the amount of volatile fatty acids (VFA) absorbed from the rumen during early lactation. Infusions of butyrate into the rumen of sheep stimulates cellular proliferation of rumen epithelial tissue, which may prove beneficial for ruminal papillae development in dairy cows during the dry period. However, no studies have investigated mechanisms associated with rumen epithelial adaptation in periparturient dairy cattle. Our hypothesis was that supplementation with cane molasses containing 34% sucrose during the prepartum period would stimulate ruminal butyrate production and ultimately promote ruminal papillae development and absorption rate, thus increasing dry matter intake (DMI) and milk production during the postpartum period. Results from these experiments indicate that diets containing cane molasses during a 60 day dry period can positively influence transition cow performance. The objective of this study was to evaluate the addition of cane molasses during a 60 day dry period on performance and metabolism of Holstein cows during prepartum and postpartum periods. For experiment 1, 26 primiparous and 28 multiparous cows were used. Upon freshening, all cows were offered a common lactation diet. For experiment 2, six multiparous cows fitted with rumen cannulas were used to measure performance and metabolism, following the same protocol as experiment 1. Ruminal propionate increased by 10% during both prepartum and postpartum periods; however, papillae area was greater for cows not fed molasses, and volatile fatty acids (VFA) absorption from the rumen was not increased, resulting in similar glucagon-like-peptide-2 receptor (GLP-2R) density. The improved dry matter intake, when molasses was added into prepartum diets, translated into increased milk yield and energy-corrected milk (ECM) in Experiment 1 only for multiparous cows. For experiment 2, the improvement on milk performance was also observed, where cows fed molasses had 18.5% greater ECM production. Feeding molasses during a 60 day dry period positively influenced transition cow performance, and it was not accompanied by changes in rumen morphometrics; however, this indicates enhanced adaptation by the rumen epithelium based on similar capabilities for VFA absorption.

Growth performance and rumen morphometrics of Nellore and ½ Angus/Nellore feedlot cattle adapted over 9 and 14 days to high-concentrate diets.

The objective of this study was to evaluate the effects of adapting Nellore and ½ Angus/Nellore (AN) feedlot cattle over periods of 9 and 14days to high-concentrate diets on performance, feeding behaviour, carcass traits and rumen morphometrics. Seventy-two yearling bulls (313.5kg±24.5), 36 Nellore and 36 AN, were randomly allocated in 24 pens (3 animals/pen; 24m2 and 2.0m of bunk space/animal) according to a randomized complete block design with a 2×2 factorial arrangement of treatments as follows: Nellore adapted for 9days, Nellore adapted for 14days, AN adapted for 9days, and AN adapted for 14days. Each treatment was composed by 6 pens (considered the experimental unit in this study). The adaptation lasted either 9 or 14days and consisted of 3 step-up diets. Therefore, yearling bulls received the finishing diet containing 86% concentrate either on day 10 or 15 of the study, which lasted 89days taking into account adaptation and finishing periods. Cattle were slaughtered in a commercial abattoir, and two 1-cm2 -rumen fragments, one from cranial and another from ventral sac, were collected. The AN cattle outperformed Nellore in terms of average daily gain (1.71kg/day vs. 1.27kg/day, p<0.01), gain:feed ratio (0.137kg/kg vs. 0.127kg/kg, p=0.02) and hot carcass weight (243.64kg vs. 228.98kg, p<0.01). No main effect of the adaptation period was observed for any of the feedlot performance and carcass traits variables evaluated. Compared to feedlot cattle adapted for 9days, feedlot cattle adapted for 14days sorted against long (0.68 vs. 0.91, p<0.01) and for fine particles (1.04 vs. 1.00, p=0.01). An interaction (p<0.01) of genotype and adaptation period was observed for rumenitis, where Nellore bulls adapted for 14days presented the highest scores. In conclusion, there was no evidence that either Nellore or AN cattle benefit from an adaptation period shorter than 14days.

PSIX-3 Feedlot performance and rumen morphometrics of Nellore cattle differing in phenotypic residual feed intake

Abstract This study, conducted at São Paulo State University feedlot, Dracena campus, Brazil, had the objective to evaluate the effect of ranking Nellore bulls according to residual feed intake (RFI) on feedlot performance and rumen morphometric variables. Twenty-seven 18-mo-old Nellore bulls (425.5 ± 20.1 kg) were randomly allocated in 27 pens (one animal per pen) and fed for 107 days. The multiple step-up diets program consisted of ad libitum feeding of diets with the concentrate level increasing from 70% to 86% concentrate. At harvest, rumen epithelium samples were collected from cranial for rumen morphometric measurements. The RFI was calculated by the difference between the predicted DMI values [DMI = (0.0544*BW0.75) + (2.9659*ADG)] and observed DMI. Then, Nellore bulls were distributed into RFI groups: High (0.5 SD above the mean; n = 8), Medium (±0.5 SD of the mean; n=9) and Low (0.5 SD below the mean; n = 10). Low-RFI Nellore bulls improved (P = 0.04) G:F when compared to High- and Medium-RFI animals (0.142 vs. 0.125 and 0.130; respectively); however, no significant RFI grouping effect was observed for ADG (P = 0.54), final BW (P = 0.54), HCW (P = 0.27), dressing percentage (P = 0.24), final LM area (P = 0.87), final 12th rib fat (P = 0.82), final P8 fat thickness (P = 0.67) and final marbling (P = 0.82). Regarding rumen morphometrics, High-RFI Nellore bulls had larger (P = 0.09) rumen absorptive surface area than Low- and Medium-RFI animals (43.31 vs. 32.95 and 31.27; respectively), which was associated to the greater (P = 0.01) DMI presented by High-RFI animals (10.2 vs. 9.1 and 9.0 for Medium- and Low-RFI Nellore bulls; respectively). Nevertheless, no significant RFI grouping effect was observed for number of papillae (P = 0.28) or mean papillae area (P = 0.61). Thus, Low-RFI Nellore bulls improved feed efficiency without promoting any positive effects on carcass traits and rumen morphometrics.

Feedlot performance, feeding behavior, carcass and rumen morphometrics characteristics of Nellore cattle submitted to strategic diets prior the adaptation period

The study was designed to evaluate the effects of either nutritional restriction or intake of concentrate feedstuffs before beginning the adaptation period on days to adapt, feedlot performance, feeding behavior, carcass characteristics, rumen and cecum morphometric of Nellore cattle. The experiment was designed as a completely randomized block, replicated 8 times (4 animals/pen), in which 96 Nellore bulls with an initial body weight (BW) of 365.52 ± 39.19 kg were fed in 24 pens according to the treatments, as follows: Restriction (Tifton hay fed at 1.4% of BW + mineral supplement); Control (Tifton hay fed ad libitum + mineral supplement) and Concentrate (Tifton hay fed ad libitum + 0.5% of BW of a mix of concentrate feedstuffs and mineral supplement). This study lasted 144-d, divided into 2 periods, as follows: 32-d of preadaptation, in which cattle were submitted to the treatments previously described, and 112-d of finishing period, where all cattle were fed the same diets. At the end of preadaptation period, one animal per pen was slaughtered (n = 24) for carcass, cecum and rumen evaluations, and the remaining 72 animals were harvested after 112-d of finishing period. No significant (P > 0.10) treatment effect was observed for days to adapt to the high-concentrate diet, which was 14 days (SEM: 0.63). Cattle submitted to restriction had greater (P < 0.10) ADG in kg (Restriction: 1.29; Control: 1.06; Concentrate: 1.18; SEM: 0.04), DMI in kg (Restriction: 9.19; Control: 8.56; Concentrate: 8.86; SEM: 0.28), G:F ratio (Restriction: 0.140; Control: 0.124; Concentrate: 0.133; SEM: 0.004), number of papillae (Restriction: 72.76; Control: 63.28; Concentrate: 62.99; SEM: 3.41) and absorptive surface area in cm2 of rumen wall (Restriction: 26.89; Control: 22.29; Concentrate: 22.30; SEM: 1.36) compared with cattle in the control group at the end of the study. Cattle submitted to either restriction or concentrate supplementation had greater (P < 0.10) final HCW in kg (Restriction: 285.35; Control: 274.10; Concentrate: 287.30; SEM: 4.51), final 12th rib fat in mm (Restriction: 4.57; Control: 3.93; Concentrate: 4.50; SEM: 0.21) and final Biceps femoris fat thickness in mm (Restriction: 6.14; Control: 5.23; Concentrate: 5.91; SEM: 0.23) compared with cattle in the control group at the end of the study. Thus, either restriction or concentrate supplementation before beginning the adaptation period to high-concentrate diets did not impact adaptation length, and both may be used as nutritional strategies to improve performance and carcass characteristics of feedlot Nellore cattle.

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

AbstractThis 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.

Feedlot performance and rumen morphometrics of Nellore cattle adapted to high-concentrate diets over periods of 6, 9, 14 and 21 days

The energy content of finishing diets offered to feedlot cattle may vary across countries. We assumed that the lower is the energy content of the finishing diet, the shorter can be the adaptation period to high-concentrate diets without negatively impacting rumen health while still improving feedlot performance. This study was designed to determine the effects of adaptation periods of 6, 9, 14 and 21 days on feedlot performance, feeding behaviour, blood gas profile, carcass characteristics and rumen morphometrics of Nellore cattle. The experiment was designed as a completely randomised block, replicated 6 times, in which 96 20-month-old yearling Nellore bulls (391.1 ± 30.9 kg) were fed in 24 pens (4 animals/pen) according to the adaptation period adopted: 6, 9, 14 or 21 days. The adaptation diets contained 70%, 75% and 80.5% concentrate, and the finishing diet contained 86% concentrate. After adaptation, one animal per pen was slaughtered (n = 24) for rumen morphometric evaluations and the remaining 72 animals were harvested after 88 days on feed. Orthogonal contrasts were used to assess linear, quadratic and cubic relationships between days of adaptation and the dependent variable. Overall, as days of adaptation increased, final BW (P = 0.06), average daily gain (ADG) (P = 0.07), hot carcass weight (P = 0.04) and gain to feed ratio (G : F) (P = 0.07) were affected quadratically, in which yearling bulls adapted by 14 days presented greater final BW, ADG, hot carcass weight and improved G : F. No significant (P > 0.10) days of adaptation effect was observed for any of feeding behaviour variables. As days of adaptation increased, the absorptive surface area of the rumen was affected cubically, where yearling bulls adapted by 14 days presented greater absorptive surface area (P = 0.03). Thus, Nellore yearling bulls should be adapted by 14 days because it led to improved feedlot performance and greater development of rumen epithelium without increasing rumenitis scores.

Different combinations of sodium monensin and virginiamycin during feedlot finishing of Nellore cattle

Context The use of two feed additives, to maximise rumen fermentation, in finishing diets offered to feedlot cattle may positively impact performance. Aims This study, conducted at the São Paulo State University feedlot, Botucatu campus, Brazil, was designed to evaluate the effects of the combined use of monensin (MON; 30 mg/kg of dry matter; (DM)) and virginiamycin (VM; 25 mg/kg of DM) in high-concentrate diets during the adaptation and finishing periods on feedlot performance, carcass traits, feeding behaviour, blood gas profile, rumen morphometrics and apparent total tract digestibility of nutrients of Nellore cattle. Methods The experiment was designed as a completely randomised block, replicated six times (3 bulls/pen), in which 72 20 months of age yearling Nellore bulls (388.0 ± 31.1 kg) were fed in 24 pens for 90 days according to the treatments: (1) MON during the entire feeding period (T1), (2) MON + VM during adaptation and only VM during the finishing period (T2), (3) MON + VM during the entire feeding period (T3), and (4) VM during the adaptation and MON + VM during the finishing period (T4). The adaptation program consisted of ad libitum feeding of three diets over the adaptation period of 19 days with concentrate level increasing from 69% to 84% of diet DM. Key results Overall, bulls fed on T2 had a greater DM intake (P &amp;lt; 0.01), final bodyweight (P = 0.04), average daily gain (P = 0.03), hot carcass weight (P &amp;lt; 0.01), final Longissimus muscle area (P = 0.05), Longissimus muscle area daily gain (P = 0.01), improved carcass G:F (P &amp;lt; 0.01) and increased dressing percentage (P &amp;lt; 0.01). Similarly, bulls fed on T2 were faster to consume 1 kg of either DM (P &amp;lt; 0.01) or neutral detergent fibre (P &amp;lt; 0.01) after 60 days on feed. Furthermore, bulls fed on T2 presented a greater (P = 0.05) cell proliferation index in the rumen papillae. Conclusions According to the results, Nellore yearling bulls should be fed high-concentrate diets containing MON and VM during adaptation, and only VM during the finishing period to improve overall feedlot performance. Implications The use of both MON and VM proved to be helpful only during the adaptation period.

The influence of Megasphaera elsdenii on rumen morphometrics of cull cows immediately stepped up to a high-energy finishing diet.

Forty-five beef cull cows [body weight (BW) = 503 ± 58 kg; body condition score (BCS) = 2.1 ± 0.6] were randomized into two treatments to compare the effects of oral drenching of no probiotic vs. 100 mL of Megasphaera elsdenii NCIMB 41125 (M. elsdenii culture; Lactipro Advance; 2 × 108 cfu/mL; MS Biotec, Inc., Wamego, KS) on the realimentation of cull cows. The study featured a rapid 0-d step-up of concentrate-naïve cull cows to a 90% concentrate diet (1.43 Mcal/kg of NEg). The cows were finished for 35 d and were fitted with a wireless rumination tag (Allflex Flex Tag; SCR Engineers, Ltd, Netanya, Israel), which tracked head movement to record eating and chewing activity. Rumen morphometrics was recorded on the harvest floor, with each carcass assigned a rumenitis score, and a fragment of the cranial sac removed for further papillae analysis. An additional 23, thin, non-fed cull cows were harvested at the same abattoir to compare the effects of concentrate realimentation on ruminal morphometrics. Megasphaera elsdenii culture-drenched cattle registered a 13.3% increase in rumination time (39.27 min/d, P = 0.03) during the first week of the trial compared to controls. A numerical rumination advantage for M. elsdenii culture-administered cattle was observed during week 2 of trial (P = 0.17), with no differences between treatments from weeks 3 to 5 (P ≥ 0.40). Subjective rumenitis evaluations approached a tendency (P = 0.12), with non-M. elsdenii culture-drenched concentrate-fed cattle logging twice the score of their day 0 cohorts (2.52 vs. 1.17) suggesting considerable lactic insults occurred to the ruminal epithelium in the short 35-d trial. Despite the short feeding duration, concentrate realimentation prompted a significant improvement in mean papillae area (P < 0.01). Among concentrate-fed treatments, M. elsdenii culture-drenched cattle posted superior absorptive surface area (P = 0.01) and a greater ratio of papillae area of absorptive surface area (P = 0.05), suggesting that M. elsdenii culture is favorably altering the ecology of the rumen and promoting papillae growth perhaps by mitigating lactate-driven pH drops. In conclusion, M. elsdenii culture application in a 0-d step-up protocol to finishing diets can help mitigate the effects of ruminal acidosis.

Effects of dietary roughage neutral detergent fiber levels and flint corn processing method on growth performance, carcass characteristics, feeding behavior, and rumen morphometrics of Bos indicus cattle1

Flint corn processing method [coarse ground corn (CGC; 3.2 mm average particle size) or steam-flaked corn (SFC; 0.360 kg/L flake density)] was evaluated in conjunction with 4 levels of NDF from sugarcane bagasse (SCB) as roughage source (RNDF; 4%, 7%, 10%, and 13%; DM basis) to determine impact on growth performance, carcass characteristics, starch utilization, feeding behavior, and rumen morphometrics of Bos indicus beef cattle. Two hundred and forty Nellore bulls were blocked by initial BW (350 ± 37 kg), assigned to 32 feedlot pens and pens within weight block were randomly assigned, in a 2 × 4 factorial arrangement (2 corn processing and 4 levels of RNDF) to treatments. Effects of corn grain processing × RNDF level were not detected (P ≥ 0.14) for growth performance, dietary net energy concentration, carcass traits, rumen morphometrics, and feeding behavior, except for time spent ruminating and time spent resting (P ≤ 0.04), and a tendency for papillae width (P ≤ 0.09). Bulls fed SFC-based diets consumed 7% less (P = 0.001), had 10.6% greater carcass-adjusted ADG (P < 0.001) and 19% greater carcass-adjusted feed efficiency (P < 0.001) compared with bulls fed CGC-based diets. Observed net energy for maintenance and gain values were 14.9% and 19.4% greater (P < 0.001), respectively, for SFC than for CGC-based diets. Fecal starch concentration was less (P < 0.001) for bulls fed SFC compared with those fed CGC. No grain processing effects were detected (P = 0.51) for rumenitis score; however, cattle fed SFC presented smaller ruminal absorptive surface area (P = 0.03). Dry matter intake increased linearly (P = 0.02) and carcass-adjusted feed efficiency tended (P = 0.06) to decrease linearly as RNDF increased. Dietary RNDF concentration did not affect carcass characteristics (P ≥ 0.19), except for dressing percentage, which tended to decrease linearly (P = 0.06) as RNDF in finishing diets increased. Increasing RNDF in finishing diets had no effect (P = 0.26) on time spent eating, but time spent ruminating and resting increased linearly (min/d; P < 0.001) with increased dietary RNDF. Steam flaking markedly increased flint corn energy value, net energy of diets, and animal growth performance, and led to improvements on feed efficiency when compared with grinding, regardless of RNDF content of diets. Increasing dietary RNDF compromised feedlot cattle feed efficiency and carcass dressing.

Nellore bulls in Brazilian feedlots can be safely adapted to high-concentrate diets using 14-day restriction and step-up protocols

In the present study, the effects of restricted intake of the final finishing diet as a means of dietary adaptation compared with diets increasing in concentrate content (step-up) over periods of 14 and 21 days on growth performance, carcass characteristics, feeding behaviour and rumen morphometrics of Nellore cattle were evaluated. One hundred and twenty 20 months old Nellore bulls (initial BW = 372.2 kg, s.d. = 21.5 kg) were randomly allocated in 24 pens (n = 5 per pen) and fed for 84 days. The study had a completely randomised design with a 2 × 2 factorial arrangement: adaptation using both 14-day and 21-day step-up and restriction protocols. Each treatment was replicated 6 times. One bull per pen was slaughtered (n = 24) at the end of adaptation period to evaluate rumen morphometrics. The remaining bulls (n = 96) were slaughtered at the end of experimental period. Interactions were observed (P &amp;lt; 0.05) for growth performance, feeding behaviour and rumen morphometrics variables. Overall, no protocol or adaptation length main effect (P &amp;gt; 0.05) was observed for any of the growth rate and carcass traits evaluated, except for hot carcass weight (P = 0.03) and dressing percentage (P = 0.04), where bulls adapted for 14 days had heavier carcasses and increased dressing percentage when compared with cattle adapted for 21 days. Cattle adapted for 21 days had a larger (P = 0.005) rumen wall absorptive surface area at the end of adaptation period than those adapted for 14 days; however, no differences were detected at the end of finishing period. Thus, Nellore yearling bulls could be adapted for 14 days regardless of the protocol.

Restricted versus step-up dietary adaptation in Nellore bulls: Effects over periods of 9 and 14 days on feedlot performance, feeding behavior and rumen morphometrics

Previous studies have shown that beef cattle can be adapted for 14 days to high-energy diets; however, the effects of adaptation periods less than 14 days on feedlot performance have not been documented in the literature. In the present study, the effects of restricted intake of the final finishing diet as a means of dietary adaptation compared with diets increasing in concentrate content (step-up) over periods of 9 days and 14 days on feedlot performance, feeding behavior, blood gas profile rumen morphometrics, nutrients digestibility and carcass characteristics of Nellore cattle were evaluated. One-hundred twenty 24 month-old Nellore bulls (361 ± 30 kg) were randomly allocated in 24 pens and fed for 84 days in a completely randomized block design with a 2 × 2 factorial arrangement of treatments: adaptation using both 9-day and 14-day step-up protocol, and 9-day and 14-day restriction protocol. Each treatment was replicated 6 times. One bull per pen was slaughtered at the end of adaptation period for ruminal evaluations. Overall, no main effect of protocols or adaptation length was observed for any of feedlot performance or carcass traits variables evaluated, with the exception of gain to feed ratio (G:F). Bulls on restriction protocol had improved G:F (P = 0.04) when compared to cattle adapted by step-up protocol. Regarding rumenitis score, there was no main effect of protocols and adaptation length (P > 0.05). For rumen morphometrics, an interaction between the effect of adaptation length and period was observed (P = 0.02) for absorptive surface area (ASA), where at the end of the adaptation period, Nellore bulls adapted for 14 days presented larger ASA than the ones adapted for 9 days; however, at the end of the finishing period, ASA from animals adapted for 14 days was similar to the ones adapted for 9 days. Thus, Nellore yearling bulls should be adapted in 14 days regardless of the protocol adopted (step-up or restriction).

Feedlot performance, feeding behavior and rumen morphometrics of Nellore cattle submitted to different feeding frequencies

Owing to the lack of information in the literature about the ideal feeding frequency adopted by feedlot systems, this study was designed to evaluate the effect of different feeding frequencies on performance, carcass traits, feeding behavior and rumen morphometrics of Nellore cattle. Forty-eight yearling bulls were housed in individual pens with an average initial body weight of 358.2 kg. The experiment was designed as a completely randomized block and the treatments were the feeding of cattle one, two, three, or four times daily (n = 12 per treatment). Orthogonal contrasts were used to assess linear, quadratic and cubic relationship between feeding frequency and the dependent variable. As feeding frequency increased, final body weight (p = 0.03) and average daily gain (p = 0.01; one: 0.98 kg d–1; two: 0.96 kg d–1; three: 1.18 kg d–1; four: 1.14 kg d–1) increased linearly and the feed:gain ratio decreased (p = 0.02). Also, as feeding frequency increased, hot carcass weight was affected cubically (p = 0.01; one: 246.9 kg; two: 243.0 kg; three: 263.1 kg; four: 258.1 kg). During the adaptation period dry matter intake variation was affected cubically (p ≤ 0.05; one: 16 %; two: 23 %; three: 14 %; four: 16 %). Increases in feeding frequency affected papillae height (p < 0.01) and papillae surface area (p < 0.01) cubically, as well as producing increases in the mitotic index (p = 0.05; one: 9 %; two: 11 %; three: 13 %; four: 13 %) and cells in proliferation (p = 0.05) linearly. Thus, Nellore yearling bulls should be fed three times daily in feedlot operations.