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.

Effects of restricted vs. step up dietary adaptation for 6 or 9 days on feedlot performance, feeding behaviour, ruminal and blood variables of Nellore cattle.

This study was designed to determine effects of quantitatively restricted intake of the final finishing diet as a means of dietary adaptation compared with diets increasing in concentrate (step up) over periods of 6 and 9 days on feedlot performance, carcass characteristics, feeding behaviour, blood gas profile and rumen morphometrics of Nellore cattle. One hundred twenty 22-month-old Nellore bulls (352 ± 20 kg) were randomly allocated in 24 pens and fed for 84 days. The experimental design was a completely randomized block with 2 × 2 factorial arrangement of treatments: adaptation using either step up protocol for 6 days or 9 days or restriction protocol for 6 days or 9 days, where the pen (five bullocks/pen; six pens/treatment) was considered the experimental unit. Cattle adapted by step up protocol had significantly greater average daily gain throughout the study when compared to those adapted by restriction protocol, regardless of adaptation length. During the adaptation period, a greater dry matter intake fluctuation was observed for animals maintained on restriction programme when compared to those adapted to the finishing diets using step up protocol. In addition, a protocol × length interaction for rumenitis scores was observed, where the level of injuries to the ruminal wall was significantly higher for the cattle adapted by restriction protocol for 9 days and lower for animals submitted for 9 days to the step up programme. Likewise, a protocol × length interaction for mitotic index was observed, in which cattle adapted by step up protocol for 9 days had lower numbers of cells in mitosis. Thus, the step up protocol led to better feedlot performance, and based on this fact, the length of 9 days promoted better rumen epithelium adaptation of Nellore cattle to high-concentrate diets.

Relationships of feedlot performance, feeding behavior, rumen morphometrics, and carcass characteristics of Nellore cattle differing in phenotypic residual feed intake.

The objective of this study was to examine the relationship of DMI fluctuation, feedlot performance, feeding behavior, rumen morphometrics, and carcass characteristics in Nellore cattle classified by residual feed intake (RFI). One experiment was conducted in 2 consecutive years using individual pens (1.0 × 7.0 m) at the São Paulo State University feedlot, Dracena campus, Brazil. The experiment in year 1 started in June of 2012 with forty-eight 20-mo-old Nellore yearling bulls with an initial BW of 358.2 ± 19.4 kg. The experiment in year 2 started in January of 2013 with sixty 20-mo-old Nellore yearling bulls with an initial BW of 402.5 ± 33.0 kg. Experiments in years 1 and 2 lasted 94 and 84 d, respectively. All yearling bulls were categorized as high RFI (>0.5 SD above the mean, = 25), medium RFI (±0.5 SD from the mean, = 56), and low RFI (<0.5 SD below the mean, = 27). Visual appraisal to collect behavior data was made on d 40 (finishing period) of both years. Yearling bulls were harvested when average across treatment groups achieved a fat thickness of 4 mm at the 12th rib. Low-RFI yearling bulls had lower daily DMI, expressed either in kilograms ( < 0.01) or as percentage of BW ( < 0.01), and improved G:F ( < 0.01) when compared to high-RFI animals. No differences were observed ( > 0.10) for ADG, final BW, or HCW among RFI groups. Also, low-RFI yearling bulls had thinner final 12th rib ( < 0.01) and biceps femoris (P8) fat thickness ( < 0.01). Low-RFI yearling bulls were slower to consume ( = 0.03) and ruminate ( < 0.01) 1 kg of either DM or NDF. No significant ( > 0.10) RFI effect was observed for any ruminal morphometrics variables evaluated, with the exception of papillae area, in which low-RFI Nellore yearling bulls tended to have smaller ( = 0.07) papillae area than medium-RFI animals. In general, low-RFI Nellore yearling bulls consumed more particles larger than 19 and 8 mm and had a similar performance when compared to both medium- and high-RFI bulls; however, carcass fat composition was negatively impacted.

Perfil de ácidos graxos e características da carne de bovinos Nelore confinados com diferentes fontes lipídicas protegidas / Fatty acids and meat characteristics of feedlot Nellore cattle with different protected fat sources

O objetivo deste trabalho foi avaliar os efeitos da adição de fontes de lipídeos naturais e protegidos da degradação ruminal na dieta de bovinos Nelore confinados sobre características da carne, concentrações de lipoproteínas sanguíneas e perfil de ácidos graxos da gordura do músculo Longissimus dorsi. Foram utilizados 120 bovinos Nelore, não castrados (366,9±28,7kg), com aproximadamente 24 meses. O delineamento experimental foi inteiramente casualizado, com três tratamentos: (CONTR) sem fonte adicional de lipídeo, (GDESP) com fonte de lipídeo natural (torta de algodão) e (GPROT) com fonte de lipídeo protegido rico em ácidos graxos poli-insaturados. Foram utilizadas 24 baias, cinco animais/baia, com oito repetições/tratamento, sendo as baias consideradas unidades experimentais. Foi observada (P<0,05) interação entre tratamento e dias de mensuração para colesterol e LDL, com maiores valores do tratamento GPROT nos dias 1 e 15, tendo o dia 84 valor intermediário aos demais tratamentos. Observaram-se efeitos de dias de mensuração, em que VLDL e triglicerídeos apresentaram valores crescentes nos dias 15, 84 e 1; enquanto o HDL teve maior valor no dia 1. Foi observado efeito (P<0,05) de tratamento para o perfil de ácidos graxos, com diminuição do C14:1, C16:1 e C17:1 e aumento do ácido transvaccênico, C18:2, ácidos graxos poli-insaturados (AGPI) e da relação AGPI: AGMI (ácidos graxos monoinsaturados) para os tratamentos GPROT e GDESP. Adição de lipídios na dieta, independentemente da fonte, promove melhora na composição de ácidos graxos da carne de bovinos Nelore confinados, aumentando a quantidade de ácidos graxos insaturados sem alterar as características qualitativas da carne.

The objective of this work was to evaluate the effects of adding sources of natural lipids and rumen-protected lipid source rich in polyunsaturated fatty acids to the diet of feedlot Nellore cattle on meat characteristics, blood lipoprotein concentration and fatty acid profile of subcutaneous fat of Longissimus dorsi. One hundred and twenty 24-mo-old Nellore yearling bulls were used (366.9±28.7kg). The experimental design was completely randomized, replicated 8 times (5 bulls/pen), with pens being considered experimental units and consisting of three treatments: (CONTR) without additional source of lipid, (GDESP) with source of natural lipid (cottonseed cake), and (GPROT) with rumen-protected lipid source rich in polyunsaturated fatty acids. Interaction (P<0.05) was observed between treatment and day of measurement for cholesterol and LDL, with values greater GPROT treatment on days 1 and 15, and day 84 intermediate value to the other treatments. Effects (P<0.05) were observed on days of measurement, which showed an increase in VLDL and triglyceride values on days 15, 84 and 1; while HDL had higher values on day 1. Effect (P<0.05) of treatment for the fatty acid profile showed decreased C14:1, C16:1 and C17:1 and increased transvaccênico acid, C18:2, polyunsaturated fatty acids (PUFA) and the ratio PUFA:MUFA (monounsaturated fatty acids) for GPROT and GDESP treatments. Additional fat in the diet, regardless of the source, promotes improvement in fatty acid composition of meat from feedlot Nellore cattle, increasing the amount of unsaturated fatty acids without changing the qualitative characteristics of meat.

Effects of feeding a spray-dried multivalent polyclonal antibody preparation on feedlot performance, feeding behavior, carcass characteristics, rumenitis, and blood gas profile of Brangus and Nellore yearling bulls.

The objective of this study was to evaluate the effects of replacing monensin (MON) with a spray-dried multivalent polyclonal antibody preparation (PAP) against several ruminal microorganisms on feedlot performance, carcass characteristics, feeding behavior, blood gas profile, and the rumenitis incidence of Brangus and Nellore yearling bulls. The study was designed as a completely randomized design with a 2 × 2 factorial arrangement, replicated 6 times (4 bulls per pen and a total of 24 pens), in which bulls ( = 48) of each biotype were fed diets containing either MON fed at 300 mg/d or PAP fed at 3 g/d. No significant feed additive main effects were observed for ADG ( = 0.27), G:F ( = 0.28), HCW ( = 0.99), or dressing percentage ( = 0.80). However, bulls receiving PAP had greater DMI ( = 0.02) and larger ( = 0.02) final LM area as well as greater ( < 0.01) blood concentrations of bicarbonate and base excess in the extracellular fluid than bulls receiving MON. Brangus bulls had greater ( < 0.01) ADG and DMI expressed in kilograms, final BW, heavier HCW, and larger initial and final LM area than Nellore bulls. However, Nellore bulls had greater daily DMI fluctuation ( < 0.01), expressed as a percentage, and greater incidence of rumenitis ( = 0.05) than Brangus bulls. In addition, Brangus bulls had greater ( < 0.01) DMI per meal and also presented lower ( < 0.01) DM and NDF rumination rates when compared with Nellore bulls. Significant interactions ( < 0.05) between biotype and feed additive were observed for SFA, unsaturated fatty acids (UFA), MUFA, and PUFA concentrations in adipose tissues. When Nellore bulls were fed PAP, fat had greater ( < 0.05) SFA and PUFA contents but less ( < 0.01) UFA and MUFA than Nellore bulls receiving MON. For Brangus bulls, MON led to greater ( < 0.05) SFA and PUFA and less ( < 0.05) UFA and MUFA than Brangus bulls fed PAP. Feeding a spray-dried PAP led to similar feedlot performance compared with that when feeding MON. Spray-dried PAP might provide a new technology alternative to ionophores.

Aditivos alimentares na dieta de bovinos confinados / Feed additives in feedlot diets

O objetivo do presente trabalho foi avaliar o efeito da inclusão do preparado de anticorpos policlonais (PAP) e/ou da monensina sódica (MON) sobre o desempenho, as características da carcaça, o perfil de ácidos graxos da carcaça (PAG) e a concentração de lipoproteínas sanguíneas (CLS) de bovinos confinados. O delineamento experimental foi inteiramente ao acaso, em arranjo fatorial 2 x 2, com medidas repetidas no tempo, sendo os fatores a inclusão ou não de MON e PAP avaliados em dois períodos, em que 72 bovinos machos da raça Brangus, não castrados, foram alocados em 24 baias (três animais/baia), totalizando seis repetições por tratamento. Não foi observado efeito (P>0,05) da inclusão do PAP para nenhuma das varáveis de desempenho e características de carcaça. Contudo, foi observado efeito (P<0,05) da inclusão de MON, em que animais que receberam MON apresentaram maiores ganho de peso diário (1,666 vs. 1,552), ganho de peso total (179,95 vs. 167,68), peso vivo final (474,86 vs. 459,61), peso de carcaça quente (248,46 vs. 240,20), melhor conversão alimentar (5,57 vs. 5,79) e reduzido custo para ganhar um quilo de peso vivo (3,06 vs. 3,18). Ainda não foi observado efeito principal (P>0,05) dos aditivos para o PAG e a CLS. Assim, a inclusão do PAP não foi boa alternativa à substituição da MON. Por outro lado, a inclusão do PAP não afetou negativamente os itens estudados.

This study was designed to test the effects of polyclonal antibody preparation (PAP) against several rumen bacteria and/or monensin (MON) on feedlot performance, carcass characteristics, fatty acid profile and blood lipoprotein concentrations in yearling bulls. Seventy-two Brangus yearling bulls were distributed in a completely randomized design with 2 x 2 factorial arrangements of treatments with six replications; factors were the inclusion or not of PAP or MON, measured over two phases. No significant (P>0.05) PAP main effects were observed for any of the feedlot performance and carcass trait variables. However, significant (P>0.05) MON main effects were observed, where animals receiving MON had higher (P<0.05) average daily gain (1.666 vs. 1.552), total weight gain (179.95 vs. 167.68), final body weight (474.86 vs. 459.61), hot carcass weight (248.46 vs. 240.20), better feed: gain ratio (5.57 vs. 5.79) and better cost to gain one kilo of body weight (3.06 vs. 3.18). No significant (P>0.05) main effects due to feed additives were observed for carcass fatty acid profile and blood lipoprotein concentrations. Therefore, the inclusion of PAP was not a good alternative to replace MON. On the other hand, feeding PAP did not negatively impact the items studied.

Effects of feeding a multivalent polyclonal antibody preparation on feedlot performance, carcass characteristics, rumenitis, and blood gas profile in Bos indicus biotype yearling bulls.

The objective of this study was to evaluate effects of feeding monensin (MON) or a multivalent polyclonal antibody preparation (PAP) against several rumen microorganisms on feedlot performance, carcass characteristics, blood gas profile, and rumenitis of Bos indicus biotype (BT) yearling bulls. The study was designed as a completely randomized design with a 3 × 2 factorial arrangement, replicated 4 times, in which 32 yearling bulls of each of 3 BT evaluated (3-way-cross, TC; Canchim, CC; and Nellore, NE) were fed diets containing either MON at 300 mg·d(-1) or PAP at 10 mL·d(-1) across 3 different periods. No significant (P > 0.10) feed additive (FA) main effects were observed for any of the feedlot performance variables and carcass characteristics with the exception of dressing percentage. Yearling bulls receiving PAP had a decreased (P = 0.047) dressing percentage when compared with yearling bulls receiving MON. Significant (P < 0.05) BT main effects were observed for all feedlot performance variables and carcass characteristics with the exception of kidney-pelvic fat expressed in kilograms (P = 0.49) and LM lipids content (P = 0.45). Crossbred yearling bulls (TC and CC) had greater (P < 0.001) ADG, DMI in kilograms, DMI as % of BW, and improved (P = 0.001) G:F when compared with NE yearling bulls. A tendency (P = 0.072) for a FA main effect was observed for rumenitis scores, in which yearling bulls receiving PAP had lesser rumenitis scores than those receiving MON. When the data were disposed as frequency percentage, 55.6% and 45.7% of the rumens from yearling bulls fed PAP and MON were scored between 0 and 1, respectively (0 = no lesions, 10 = severe lesions). Likewise, a significant BT main effect was observed (P = 0.008), where NE yearling bulls had greater rumenitis scores than those of crossbred yearling bulls (TC and CC). No significant FA main effects were observed (P > 0.10) for any of the fatty acids measured in the subcutaneous adipose tissue, with the exception that yearling bulls receiving MON had greater (P < 0.05) concentrations of palmitic acid (16:0), margaric acid (17:0), docosapentaenoic acid (22:5), and docosahexaenoic acid (22:6) than those yearling bulls receiving PAP. Feeding PAP tended to decrease incidence of rumen lesions and led to similar feedlot performance compared with feeding MON. Thus, PAP is a new technology that presents a possible alternative for ionophores.

Effects of adding polyclonal antibody preparations on ruminal fermentation patterns and digestibility of cows fed different energy sources.

Nine ruminally cannulated cows fed different energy sources were used to evaluate an avian-derived polyclonal antibody preparation (PAP-MV) against the specific ruminal bacteria Streptococcus bovis, Fusobacterium necrophorum, Clostridium aminophilum, Peptostreptococcus anaerobius, and Clostridium sticklandii and monensin (MON) on ruminal fermentation patterns and in vivo digestibility. The experimental design was three 3 × 3 Latin squares distinguished by the main energy source in the diet [dry-ground corn grain (CG), high-moisture corn silage (HMCS), or citrus pulp (CiPu)]. Inside each Latin square, animals received one of the feed additives per period [none (CON), MON, or PAP-MV]. Dry matter intake and ruminal fermentation variables such as pH, total short-chain fatty acids (tSCFA), which included acetate, propionate, and butyrate, as well as lactic acid and NH(3)-N concentration were analyzed in this trial. Total tract DM apparent digestibility and its fractions were estimated using chromic oxide as an external marker. Each experimental period lasted 21 d. Ruminal fluid sampling was carried out on the last day of the period at 0, 2, 4, 6, 8, 10, and 12 h after the morning meal. Ruminal pH was higher (P = 0.006) 4 h postfeeding in MON and PAP-MV groups when compared with CON. Acetate:propionate ratio was greater in PAP-MV compared with MON across sampling times. Polyclonal antibodies did not alter (P > 0.05) tSCFA, molar proportion of acetate and butyrate, or lactic acid and NH(3)-N concentration. Ruminal pH was higher (P = 0.01), 4 h postfeeding in CiPu diets compared with CG and HMCS. There was no interaction between feed additive and energy source (P > 0.05) for any of the digestibility coefficients analyzed. Starch digestibility was less (P = 0.008) in PAP-MV when compared with CON and MON. In relation to energy sources, NDF digestibility was greater (P = 0.007) in CG and CiPu vs. the HMCS diet. The digestibility of ADF was greater (P = 0.002) in CiPu diets followed by CG and HMCS. Feeding PAP-MV or monensin altered ruminal fermentation patterns and digestive function in cows; however, those changes were independent of the main energy source of the diet.

A snapshot of management practices and nutritional recommendations used by feedlot nutritionists in Brazil.

Feedlot consulting nutritionists were invited to participate in a survey of feedlot nutritional and management practices in Brazil. Thirty-one nutritionists completed the survey on a Web site that was designed for collection of survey data. The survey consisted of 94 questions that included general information (n = 10); commodity information (n = 12); and questions about the use of coproducts (n = 5), roughage source and levels (n = 5), finishing diet adaptation methods (n = 7), supplements and micronutrients (n = 8), feed mixers (n = 6), feeding management (n = 3), cattle management and type of cattle fed (n = 16), formulation practices (n = 17), information resources used for nutritional recommendations (n = 2), and 2 additional questions. One final question addressed the primary challenges associated with applying nutritional recommendations in practice. The number of animals serviced yearly by each nutritionist averaged 121,682 (minimum = 2,000; maximum = 1,500,000; mode = 120,000; total = 3,163,750). Twenty-two respondents (71%) worked with feedlots that feed less than 5,000 animals/yr. Labor, along with availability and precision of equipment, seemed to be the main challenges for the nutritionists surveyed. Most of the nutritionists surveyed used TDN as the primary energy unit for formulation. More than 50% of the clients serviced by the 31 nutritionists did not manage feed bunks to control the quantity of feed offered per pen, and 36.6% fed cattle more than 4 times daily. The NRC (1996) and Journal of Animal Science were the most used sources of information by these nutritionists. Overall, general practices and nutritional recommendations provided by the 31 nutritionists surveyed were fairly consistent. Present data should aid in development of new research, future National Research Council models, and recommendations for Brazilian feeding systems in which Bos indicus cattle predominate.

Effect of single nucleotide polymorphisms of CAPN1 and CAST genes on meat traits in Nellore beef cattle (Bos indicus) and in their crosses with Bos taurus.

The objectives of this work were to study the segregation of single nucleotide polymorphisms of the calpain 1, large subunit (CAPN1) and calpastatin (CAST) genes in Nellore (Bos indicus) and Nellore xBos taurus beef cattle, as well as to evaluate their effects on meat traits. For this, 300 animals, including 114 Nellore, 67 Angus x Nellore, 44 Rubia Gallega x Nellore, 41 Canchim, 19 Brangus three-way crosses and 15 Braunvieh three-way crosses, were genotyped for the CAPN4751 [AF_248054.2:g.6545C>T (GenBank accession AF248054.2)] and CAST/DdeI [AF_159246.1:g.2959A>G (GenBank accession AF159246.1)] polymorphisms and phenotyped for Ribeye Area, Backfat Thickness, Intramuscular Fat, Shear Force (SF) and Myofibrillar Fragmentation Index (MFI). In relation to the CAPN4751 polymorphism, a frequency of 10.5% was observed for the C allele in the Nellore breed. In the total sample of studied animals, a significant association was found between genotypes and meat tenderness, assessed by SF (P = 0.005) and MFI (P = 0.008), with genotype CT being more favourable than TT. For the CAST/DdeI polymorphism, a frequency of 55.7% was found for the A allele in the Nellore breed. In the total sample, a significant association was observed between genotypes and meat tenderness - SF (P = 0.004) and MFI (P = 0.006), with genotype AA being more favourable than AG. The relationship between genotypes and aged meat tenderness in confluence with the distribution of favourable alleles shows great potential for application of the CAPN4751 and CAST/DdeI polymorphisms in the genetic improvement of the Nellore breed, whilst contributing to the validation, in this breed and in its crosses with B. taurus, of the association results previously described in the literature.