ABSTRACT The objectives were to evaluate the effects of monensin and virginiamycin, alone or combined, on supplemented Nellore cattle grazing tropical grass during the rainy season. Two experiments were conducted simultaneously to evaluate intake, digestibility, CH4 emissions, blood parameters, performance, and carcass characteristics (Exp. 1), and ruminal fermentation and relative abundance of ruminal microorganisms (Exp. 2). Animals (n = 92 Exp. 1 and n = 12 Exp. 2) were distributed in a completely randomized design and allocated in twelve paddocks composed of Urochloa brizantha (A. Rich.) Stapf. cv. Xaraés. A protein-energetic supplementation of 3 g/kg of BW per day was provided to all animals. Supplements were: without additives (WA), monensin alone at 80 mg/kg of product (MN), virginiamycin alone at 150 mg/kg of product (VM), and monensin (80 mg/kg of product) combined with virginiamycin (150 mg/kg of product; MNVM). Treatments did not affect intakes of total dry matter (DM), supplement DM, and nutrients. However, the intakes of forage DM and crude protein decreased in cattle fed MNVM compared with animals fed WA, MN, and VM. Total volatile fatty acids increased in animals fed VM. Ruminal NH3-N decreased, and pH increased in animals fed MN, VM, and MNVM. Relative abundance of total F. succinogenes and S. ruminantium decreased and R. flavefaciens increased in animals fed MN and VM at d 118. Treatments had no effect on enteric CH4 emissions. The average daily gain (ADG) and total gain were greater in cattle fed MNVM than in cattle fed MN. Combination of monensin and virginiamycin altered the rumen microbial populations but did not decrease enteric CH4 emissions. However, it decreased forage dry matter intake without altering the ADG and total weight gain, leading to an increase in feed efficiency. Results from this study indicate an advantage in including feed additives combined in the diet of supplemented Nellore cattle grazing tropical grass during the rainy season.

Abstract The aim of this study was to determine the effects of different amounts of crude glycerol (CGL) on dry matter intake, milk yield, milk protein yield, and milk fatty acid profile of dairy cows grazing on a Kikuyu-based pasture. Six Holstein cows were used in the first third of lactation (mean ± SD 559 ± 22.5 kg body weight, 43 ± 10 days in milk, and 26.8 ± 1.2 kg milk/day) and were randomized within a replicated 3 × 3 Latin square arrangement. Animals grazed the Kikuyu grass and were supplemented with a commercial energy-protein concentrate at 1.0 kg/4.0 kg of milk. The experimental period was 69 days. The following treatments were administered: CGL0 (control, without glycerol), CGL1 (750 g/cow/day), and CGL2 (1,500 g/cow/day). The addition of 750 and 1,500 g of CGL did not affect grass and concentrate intake (P > 0.05). However, milk yield (FCM 3.5%) increased by 14.2% in the CGL2 group compared to that obtained in the control group (CGL0) (P = 0.02). The addition of 1,500 g of CGL to the diet resulted in a 2.1% greater yield of milk protein compared to that obtained with CGL0 treatment (P = 0.01). Further, the addition of 1,500 g of CGL did not impact grass intake, milk fat concentration, or fatty acid composition (P < 0.05). Thus, the inclusion of CGL as a co-product may be a nutritional strategy to increase the productivity of dairy production systems in tropical perennials, such as Kikuyu grass.

ABSTRACT. This study evaluated the effect of phosphorus (P) supplementation on the intake, digestibility, and quality of aged meat from Nellore young bulls fed on high-grain diets finished in feedlot. Forty young bulls (30 months old) with an initial body weight (IBW) of 296 ± 25 kg were used. It was distributed in a completely randomized experimental design. The treatments were: without P supplementation (CO), commercial mineral supplement (CM), and supplementation with dicalcium phosphate (DP) with 2.4, 4.2, or 5.0 g of P per kg of dry matter (DM), respectively. Diets were composed of sugarcane bagasse (200 g kg-1) plus concentrate (800 g kg-1) on a dry matter (DM) basis. The meat quality parameters analyzed were pH, color, cooking losses, shear force, and water-holding capacity. P supplementation did not affect the intake and digestibility of nutrients There was no interaction (p > 0.05%) between diets and the aging time for the meat quality parameters. However, bulls fed with DP exhibited lower pH (5.98) compared to CO and CM (6.19 and 6.14, respectively). The longer aging time increased the cooking losses and intensity of yellow (b*). Under Brazilian conditions, feedlot Nellore cattle fed with high-grain diets do not require additional mineral supplements.

RESUMO. Doze novilhos canulados no rúmen (401,0 ± 41,5 kg) e 24 meses de idade foram usados em delineamento de quadrado latino truncado replicado com seis animais, seis tratamentos e quatro períodos, para avaliar o efeito da glicerina bruta (GB; 80,3% de glicerol) com amido ou ingredientes energéticos a base de fibra no concentrado sobre o CMS, digestibilidade da MS (DMS) e FDN (DFDN) e parâmetros ruminais. O período experimental foi 19 dias (14 dias de adaptação e 5 dias de coleta). As dietas foram: CO - sem glicerina bruta e milho como ingrediente do concentrado; GBM - GB (10% da MS) com milho no concentrado; GBCS - GB (10% da MS) com casca de soja no concentrado. As três dietas foram ofertadas em baixo (BC) ou alto (AC) teor de concentrado (TC; 40 ou 60%). Animais alimentados com BC ou AC apresentaram similar CMS, DMS e DFDN. Animais alimentados com GB com milho ou CS apresentaram maior concentração de propionato e menor relação A:P. Dietas com AC aumentou a concentração de propionato mas não afetou a DFDN. GB (10% da MS) pode ser usada para substituir o milho ou CS em dietas com 40 ou 60% de concentrado, sem afetar a DFDN.

ABSTRACT. Twelve ruminally cannulated steers (401.0 ± 41.5 kg) and 24 mo were used in a replicated arrangement truncated Latin Square with six animals in six treatments and four periods to evaluate the effect of crude glycerine (CG; 80.3% of glycerol) with starch or fiber-based energy ingredients in the concentrate on DMI, DM (DMD) and NDF digestibility (NDFD) and ruminal parameters. Experimental periods were 19 days (14 days for adaptation and 5 days to sampling). Diets were: CO - without CG and corn as ingredient of concentrate; CGC - inclusion of CG (10% of DM) with corn in the concentrate; and CGSH - inclusion of CG (10% of DM) with soybean hulls (SH) in the concentrate. All three diets were offered at low (LC) or high (HC) concentrate level, CL (40 or 60%). Animals fed LC or HC diets had similar DMI, DMD and NDFD. Animals fed diets with CG associated with corn or SH had higher propionate concentrations and lower A:P ratio. Diets with HC increase the propionate but do not affect the NDFD. CG (10% of DM) can be used to replace corn or SH in diets with 40 or 60% of concentrate, without affect NDFD.

ABSTRACT The objective of this study was to evaluate the effect of lipid sources on voluntary intake, digestibility, performance, and CH4 emission of Nellore steers grazing Brachiaria brizantha cv. Xaraés forage in the dry season. Forty-five Nellore steers with average weight of 442±34 kg were alloted into one of the five treatments: without additional fat; with palm oil; with linseed oil; with protected fat; and with whole soybeans. The supplements were provided daily and quantities were adjusted to 1% of body weight and diets were formulated in accordance with the Cornell Net Carbohydrate and Protein System. The experimental design was completely randomized with five treatments and two replications. There were no effects on dry matter, organic matter, and neutral detergent fiber intake with the inclusion of lipids in the diet. The neutral detergent fiber showed decreased digestibility in animals receiving linseed oil and palm oil treatments compared with animals receiving the diet without additional fat. The linseed oil treatment reduced CH4 emissions by 38% when expressed in mg/d/kg BW and tended to reduce the emission in g/d/kg BW0.75. Lipid sources did not affect the weight gain of the animals. The intake and performance of grazing Nellore steers supplemented at 1% body weight with lipid sources were not modified. However, fiber digestibility was reduced with palm or linseed oil addition. Linseed oil reduced enteric CH4 emissions. Linseed oil has the potential to reduce enteric CH4 emissions in continuous tropical grazing systems based on B. brizantha grass.

ABSTRACT The objectives of this study were to evaluate the effect of forages with different nutritional values - specifically, corn silage (CS), sugar cane (SC), and sugar cane bagasse (SB) - in diets with crude glycerin, on carcass traits, meat quality, and fatty acid profile, using young Nellore bulls finished in the feedlot. Thirty young Nellore bulls with an initial average body weight of 416.70±24.74 kg were randomly assigned to three treatments containing different sources of forage. The carcass traits and variables related to meat quality of the Nellore young bulls were not significantly influenced by different sources of forage in diets with crude glycerin. The yellow color index was significantly greater in the fat of animals fed corn silage. Heptadecenoic fatty acid was significantly lower in the meat of animals fed sugar cane bagasse. The sources of forage in diets with crude glycerin did not influence the profile of saturated, monounsaturated, or polyunsaturated fatty acids in the longissimus muscle. Overall, our results indicate that none of the treatments changed the carcass and meat quality traits of Nellore young bulls finished in the feedlot. Thus, sugar cane and sugar cane bagasse could be used in feedlot as a viable forage alternative to corn silage.

RESUMO. Foram estudadas as características qualitativas de cinco músculos, maturados ou não, de quatorze bovinos da raça Nelore com 450 kg ± 30,7 kg de peso corporal e confinados por 60 dias com dieta contendo 60% de concentrado e 40% de volumoso na MS. Após o abate e resfriamento das carcaças, amostras dos músculos: picanha, (Biceps femoris - BF), contrafilé (Longissimus - LD), alcatra (Gluteus medius - GM), lagarto (Semitendinosus - ST) e acém (Trapezius thoracis - TT) foram retirados, embalados à vácuo e maturados em câmara B.O.D (0 a 2oC) por um, sete e 14 dias e posteriormente armazenadas a -20oC para análises químicas e de qualidade. Os dados foram analisados em um delineamento em split-plot utilizando o procedimento PROC MIXED do SAS. A maturação influencia nas características qualitativas e químicas da carne bovina, melhorando aspectos como a maciez (p < 0,01) e a luminosidade (p < 0,01). O músculo Trapezius thoracis tem uma maior estabilidade de cor quando comparado com o músculo Longissimus. Não é recomendada a maturação do músculo ST em razão deste não apresentar melhora em sua maciez. Os músculos GM e BF apresentam-se macios logo no primeiro dia, sendo que o processo de maturação para estes cortes é indicado em razão de agregar valor à carne.

ABSTRACT. This trial aimed to assess the qualitative traits of five muscles of 14 Nellore bulls with 450 kg ± 30.7 kg BW, feedlot fed for 60 days. After slaughter and carcass chilling, samples of the Biceps femoris (BF), Longissimus (LD), Gluteus medius (GM), Semitendinosus (ST) and Trapezius thoracis (TT) muscles were collected, vacuum-packed and aged at 0 to 2 ºC for 1, 7 and 14 days and subsequently stored at -20ºC for chemical and quality analysis. The pH, shear force, water holding capacity, cooking losses, meat color and ether extract were evaluated in all aging times. Data were analyzed in a split-plot design using the PROC MIXED procedure of SAS. Aging affected quality traits and chemical properties of the meat, improving aspects, such as tenderness (p < 0.01) and lightness (p < 0.01). The Trapezius thoracis muscle has a higher color stability compared with the Longissimus muscle. Aging is not recommended for the ST muscle because the tenderness is not improved. The GM and BF muscles are tender on the first day, and the aging process is indicated for these cuts for adding value to the beef.

Objetivou-se avaliar a inclusão de 10% de glicerina bruta (GB) associada a fontes de volumosos sobre a qualidade da carne maturada em 24 horas, sete e 14 dias post mortem de tourinhos da raça Nelore. Utilizaram-se 30 animais confinados (n = 10), com peso inicial de 416,70 ± 24,74 kg e 18 meses de idade, sendo submetidos aos três tratamentos: silagem de milho (SM), cana-de-açúcar (CA) ou bagaço de cana (BC), utilizando delineamento inteiramente casualizado. Após 85 dias, os animais foram abatidos com 554,51 ± 38,51 kg. Amostras do longissimus foram coletadas após resfriamento das carcaças e embaladas a vácuo. A dieta influenciou o pH, a coloração da carne e da gordura subcutânea (GS; p < 0,05). Animais alimentados com SM apresentaram maior valor de b* na GS (p < 0,05). A dieta não modificou o perfil de ácidos graxos (AG) da carne (p > 0,05). A maturação influenciou pH e força de cisalhamento da carne (FC; p < 0,05). Carnes maturadas aos 14 dias apresentaram maior pH (5,90) e menor FC (2,40 kgf). Dietas contendo 10% GB na MS associada à SM, CA ou BC não modificam os AG da carne. A maturação em 14 dias reduz a FC do longissimus, melhorando a qualidade da carne.

This trial aimed to evaluate the inclusion of 10% of crude glycerin associated with roughage sources on the quality of meat aged for 1, 7 or 14 days post mortem of Nellore young bulls. Thirty feedlot animals (n = 10) with initial body weight of 416.70 ± 24.74 kg and 18 months of age were assigned to three treatments: corn silage (CS), sugar cane (SC) and sugar cane bagasse (CB), using a completely randomized design. After 85 days of feeding, animals were slaughtered with 554.51 ± 38.51 kg. Samples of longissimus muscle were collected, after carcass chilling, and vacuum-packed. Diets influenced pH, meat color and subcutaneous fat (SF) (p > 0.05). Animals fed CS showed higher values of b* in SF (p < 0.05). Differences were not found in the meat fatty acid profile (p > 0.05). Aging times influenced pH and shear force of beef (p < 0.05). Beef aged for 14 days showed higher pH (5.90) and lower shear force (2.40 kgf). Diets containing 10% crude glycerin in the DM associated with CS, SC or CB had no effect on the fatty acid profile in beef. The aging process for 14 days reduces shear force, improving meat quality.

Objetivou-se neste trabalho avaliar a qualidade da carne maturada de tourinhos Nelore, sob dois graus de acabamento (GA) de carcaça. Foram utilizados 14 animais, com aproximadamente 450 ± 30 kg de peso corporal. A espessura de gordura subcutânea (EGS) dos animais foi avaliada no início do período experimental. Foram escolhidos 14 animais com EGS de 0-3 mm e 3,1-6 mm, formando-se dois grupos ao final do experimento: animais com acabamento entre 3-6 mm (sete animais) e entre 6,1-10 mm (sete animais). A cada 28 dias foram avaliados a EGS entre a 12-13ª costelas com ajuda de unidade ultrassonográfica. Os valores de coloração da carne, pH, perdas por cocção e força de cisalhamento não tiveram efeito de interação entre os tratamentos (p > 0,05). Não houve diferença significativa entre o GA sobre o comprimento de sarcômero (p = 0,11). Houve interação entre GA e maturação sobre a capacidade de retenção de água (p < 0,01). Os graus de acabamento avaliados não interferem na qualidade da carne, mas carcaças com acabamento entre 6,1-10 mm apresentam maior capacidade de retenção de água. A maturação do músculo longissimus em até 14 dias melhora a maciez da carne.

This trial aimed to evaluate the quality of aged beef from Nellore young bulls under two yield grade (YG). Fourteen animals with approximately 450 ± 30 kg body weight were evaluated for backfat thickness (BFT) at the beginning of the experimental period. Seven animals had BFT of 0-3 mm and seven animals, 3.1-6 mm. Two groups were formed at the end of the experiment: animals finished with 3-6 mm BFT (seven animals) and animals finished with 6.1 to 10 mm BFT (seven animals). Every 28 days, we evaluated by ultrasound the BFT between the 12nd 13rd ribs. There was no interaction between YG and aging for beef color, pH, cooking losses and shear force (p > 0.05). There was no effect of YG on sarcomere length (p = 0.11). However, there was interaction between YG and aging on water holding capacity (p < 0.01). The yield grades evaluated did not interfere with meat quality, but carcasses with 6.1 - 10 mm of backfat thickness showed highest water holding capacity. The aging of the longissimus muscle for up to 14 days improves beef tenderness.

The present study was conducted to investigate the effect of alternative true-protein sources to soybean meal, with different ruminal degradability, using a sugarcane-based diet, on nutrient digestion, ruminal fermentation, efficiency of microbial protein synthesis and passage rate in prepubertal dairy heifers. Eight crossbred rumen- and duodenum-cannulated Holstein × Gyr dairy heifers (202.0±11.5 kg BW) were evaluated in a 4 × 4 Latin square experimental design with four treatments and four periods in two simultaneous replicates. Dietary treatments were: soybean meal; cottonseed meal; peanut meal; and sunflower meal. When associated with diets containing sugarcane, the different protein sources did not affect intake or digestibility of dry mater, crude protein, organic matter and neutral detergent fiber. The average ruminal pH, NH3-N and concentration of total volatile fatty acids were not different among the diets supplied. The concentration of butyric acid was different among the protein sources, wherein the animals fed the diet with sunflower meal presented lower values than those fed the other sources. Diets did not affect nitrogen balance, microbial nitrogen, microbial synthesisefficiency, estimated dry matter flow, or passage rate. Alternative protein sources can be used to reduce the costs without changing the animal metabolism.

The objective of this study was to evaluate nutrient intake, performance, estimated methane production and carcass characteristics of steers fed diets containing three different levels of soybean grain: 0, 120 and 230 g/kg on the dry matter (DM). The study was conducted on eighteen castrated Nellore males with an average initial body weight (BW) of 370±12 kg in a completely randomized design, with three treatments and six repetitions. Intake of dry matter (DMI, kg/day) and crude protein tended to decrease linearly, and the intake of ether extract increased linearly in response to the soybean grain levels in the diet. Levels of soybean grain in the diet did not affect DMI (g/kg of BW), final average weight, average daily weight gain, feed efficiency and estimated methane production. Animals fed diets with different levels of soybean grain were not different with respect to carcass yield, loin eye area, subcutaneous fat thickness, or bone, muscle and fat ratios. Carcass characteristics and meat quality were also not significantly different. Replacement of soybean meal by soybean grain in the diet alters the intake of crude protein and ether extract but does not affect performance, estimates of methane production, or carcass characteristics of feedlot Nellore.

The objective of this study was to evaluate the characteristics of ruminal fermentation and enteric methane production in beef cattle subjected to different supplementation frequencies while grazing on Brachiaria brizanthacv. Marandu pastures. Nine cattle (325±65.7 kg BW) fitted with ruminal and duodenal cannulas were used in the ruminal fermentation study, and 12 cattle (399±32.6 kg BW) were used in the enteric methane production study. The treatments included supplementation once daily, supplementation once daily except Saturdays and Sundays, or supplementation on alternate days. The supplementation was equivalent to 10 g kg−1 BW day−1 for all treatments. The design employed was completely randomized with three treatments and three replications. When all supplements were provided (day 1), no effects of supplementation frequency were observed on ruminal pH; concentration of NH3-N; concentration of acetic, propionic, or butyric acids; or total volatile fatty acids (VFA), but there were month effects. During the day on which only daily supplements were provided (day 2), significant differences were observed only on the molar concentration of acetic acid and total VFA; and month effects were noted on all variables. No significant differences were observed in ruminal fluid volume, dilution rate, N intake, bacterial N synthesis and enteric methane production among the studied supplementation frequencies. Differences were observed in the enteric methane production in the different months, with 85 g kg−1 of gross energy intake observed in September and 123 g kg−1 of gross energy intake observed in November. Lower supplementation frequency is a good option to lower labor costs with little or no consequences on ruminal fermentation characteristics and enteric methane production.

Reduced supplementation frequency is a broadly applied management practice. Ruminants consuming low quality forages/pastures, supplemented less than once daily are able to maintain body weight gain (BWG), efficiency of use of dry matter, nitrogen and other nutrients, as compared with animals supplemented once daily. We evaluated the feeding behavior, dry matter intake (DMI), dry matter and organic matter digestibility (DMD and OMD), BWG, Longissimus muscle area and backfat depth of Nellore steers raised on Brachiaria brizantha cv. Marandu pastures during the dry season, with different supplementation patterns. Thirty six animals (338 ± 40.7 kg) were distributed over nine paddocks according to a completely randomized design. Treatments were based on supplementation frequency: once daily (OD), once daily except Saturdays and Sundays (SS), or on alternate days (AD), at 1.0 %, 1.4 % and 2.0 % BW, respectively. Average total DMI accounted for 1.6 % BW day-1, with no effect of supplementation frequency. Supplementation frequency had no effect on BWG or grazing time during the day. There was no difference in Longissimus muscle area animals supplemented daily, SS and AD. The backfat depth was thinner in animals supplemented AD, but even in this case, it was within the standards considered satisfactory for a finishing steer. Reducing supplementation frequency seems a good option to lower labor costs without affecting feed efficiency or carcass quality in beef cattle grazing tropical pastures.

The objective of this study was to evaluate the postweaning history of heifers kept on marandu grass pastures with three canopy heights, in a continuous-grazing system, during the rainy period, on feedlot- or pasture finishing. The effects of three canopy heights (15, 25 and 35 cm) associated with two supplements (mineral salt and protein-energy supplement) and two finishing systems in the dry period (feedlot and open pasture) were studied in the postweaning period during the rainy season. The adopted design was completely randomized, with seven replications (animals) in a 2 × 2 factorial arrangement. The animals which received protein-energy supplement reached the finishing period with greater body weight in relation to those fed mineral salt. In both feedlot and pasture finishing systems, compensatory gain effect was observed in the animals that remained on the low pastures during postweaning compared with the high pastures. This compensatory gain was not verified in the animals that received protein-energy supplement in relation to the mineral salt, and thus the animals were slaughtered beforehand. The heifers on pastures with 25 or 35 cm in height were slaughtered in the same period, and those kept on the low pastures were slaughtered afterwards. The studied factors in the postweaning phase did not affect the carcass characteristics. Animals finished in feedlot slaughtered with the same body weight as those finished on pasture show greater carcass yield, subcutaneous fat deposition and renal pelvic and inguinal fat and greater losses with trimmings for cleaning the main hindquarter meat cuts; however, they provide cuts with the same weight but greater fat cover.

Foram avaliados descarte de resíduos químicos em análises dos teores de fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA), utilizando métodos convencional (Van Soest) e alternativos de análises. A recuperação da acetona promoveu ganhos tanto econômico como ambiental, observando-se taxa de recuperação de 84,12%. A precisão das análises não foi observada na maioria das determinações com reutilização de resíduos químicos, em todos os métodos analíticos testados, apesar de promover redução no custo, no tempo investido no preparo das soluções e no descarte de resíduos químicos.

The disposal of chemical waste and the precision of analyses of the neutral (NDF) and acid (ADF) detergent fiber contents were evaluated utilizing conventional (Van Soest) and alternative methods of analyses. The recovery of acetone promoted both economic and environmental gains, with a recovery rate of 84.12%. The precision of the analyses was not observed in most of the determinations with reutilization of chemical waste in all the analytical methods tested, in spite of promoting decrease in cost, time invested in the preparation of solutions and the disposal of chemical waste.