Rodrigo da Costa Gomes

Protein metabolism, feed energy partitioning, behavior patterns and plasma cortisol in Nellore steers with high and low residual feed intake

The objective was to evaluate protein turnover, nitrogen balance, feed energy partitioning, behavior patterns and plasma cortisol in Nellore (B. indicus) cattle with high and low residual feed intake (RFI = actual minus expected dry matter intake). Seventy-two Nellore steers (16 to 21 months-old, 334±19 kg initial body weight) were fed a feedlot diet for 70 days ad libitum. Daily dry matter intake (DMI) and average daily gain (ADG) were recorded individually and RFI was calculated. The 12 steers of lowest (Low-RFI, most efficient) RFI and the 12 ones of highest RFI (High-RFI, least efficient) were evaluated with respect to their behavior patterns and plasma cortisol concentration. Urine was collected for determination of daily 3-methylhistidine excretion (3MH) and myofibrillar protein breakdown rates. Urinary, gaseous and fecal energy losses were determined as well as the N retention and excretion. High-RFI steers tended to have shorter lying and idle periods and greater feeding time and plasma cortisol levels than low-RFI cattle. No RFI effects were seen for urine 3MH excretion and for rates of protein degradation and synthesis. No effects of efficiency class were observed for N excretion or N retention. No RFI effects were observed for dry matter digestibility, digestible energy (DE) and metabolizable energy (ME) content and DE/ME ratio. Methane energy losses were lower for low- compared with high-RFI steers. Protein turnover seems not to affect feed efficiency in Nellore steers. Improved RFI in Nellore steers is probably associated with lower degrees of activity and responsiveness to stress and lower losses of dietary energy as methane.

Hematological profile of beef cattle with divergent residual feed intake, following feed deprivation

Abstract – The objective of this work was to characterize the hematological profilesof steers and bulls, according to residual feed intake (RFI), after feed deprivation. Twenty‑month‑old Nellore steers and bulls were fed feedlot diets for 70 and 56 days, respectively. RFI was calculated as the difference between actual feed intake and expected feed intake. More and less efficientsteers and bulls, according to RFI, were subjected to 24 hours of food deprivation. Blood was sampled prior to and following the withdrawal period. Hematological analyses included total and differential white blood cell count, red blood cell count and morphology, and plasma glucose concentration. Variation in RFI did not influenceplasma glucose concentration or blood cell profiles.Glucose concentrations -in bulls decreased from 114 to 97 mg dL1, but remained unchanged in steers, and the neutrophil:lymphocyte ratio increased from 0.39 to 0.57 following deprivation. Hematological profiles do not differ between more and less efficient steers and bulls, according to RFI.Index terms:

Correlations of visual scores, carcass traits, feed efficiency and retail product yield in Nellore cattle

The growing use of visual scores (VS) and ultrasound (US) for carcass evaluation in breeding programs, calls for a knowledge of the relationships between these traits and other relevant characteristics, such as feed efficiency and production of commercial cuts. The objective of this study was to evaluate correlations between body visual scores and carcass traits identified by ultrasound (US) and feed efficiency (FE), carcass weight (HCW), dressing percentage (DP) and retail product yield (RPY) in beef cattle. Nellore cattle (male), 42 non-castrated [NCAST] and 44 castrated [CAST]) were evaluated by both VS and US, at the postweaning (15-month old) and finishing phases (21-month old). Visual scores of conformation (C), precocity (P) and muscling (M) were assessed and the backfat thickness (UBFT), rump fat thickness (URFT) and ribeye area (UREA) were measured by ultrasound. Gain-to-feed (G:F) ratio and residual feed intake (RFI) were measured in feedlot. Hot carcass weight, DP and RPY were determined at harvest. Non-castrated cattle had greater HCW and RPY but lower UBFT and URFT than CAST. Postweaning VS and US were poorly correlated with FE in both sexual conditions. Finishing VS were negatively correlated with G:F in CAST and finishing URFT was negatively correlated with RPY in NCAST. The relationship of VS and US with feed efficiency and meat yield is affected by age at the date of evaluation and by castration. Feed efficiency is not related to the yield of meat cuts in Nellore cattle

Prediction of retail beef yield, trim fat and proportion of high-valued cuts in Nellore cattle using ultrasound live measurements

The objective of this study was to develop equations to predict retail product and fat trim (weights and percentages) for Nellore (Bos indicus) cattle. Live ultrasound measurements of the longissimus muscle area, backfat thickness at the 12th rib and rump fat depth and shrunk body weight were obtained from 218 Nellore steers to predict weights and percentages of carcass retail product, pistola retail product and fat trimmings. After slaughter, carcasses were deboned and weighed and percentages of retail cuts were obtained directly. Measurements taken directly in the carcasses explained 97% and 36% of variation in carcass retail product weight and percentage, and 94% and 36% of variation in pistola retail weight and percentage, respectively. Live measurements explained 93% of carcass retail product weight and 39% of carcass retail product percentage. Lower accuracies were observed for pistola retail product weight (R2=0.87) and percentage (R2=0.33). Accuracies for fat trimmings weight and percentage were 79% and 55%, respectively. Ultrasound rump fat thickness showed greater correlations with retail product and fat trimmings (weights and percentages) when compared with ultrasound backfat thickness. The weight and percentage of retail products and of trimmable fat can be estimated in Nellore steers from live animal measurements, with similar accuracy to equations developed based on carcass measurements obtained at slaughter.

Supplemental fish oil does not alter immune competence or the pathophysiological response to an intramammary infusion of endotoxin in peri-partum multiparous Holstein cows

The objective was to determine the effects of supplementing the diet with fish oil during the peri-partum period on the immune competence and the pathophysiological response to a lipopolysaccharide-induced mastitis challenge. Multiparous Holstein cows (n=30) were completely randomized to one of two treatments at 3 weeks pre-partum. Treatments differed only in the source of supplemental lipid and included either Energy Booster or fish oil. Treatment diets were fed from -21 d relative to expected date of parturition until 10 d post partum. Treatments were fed as a bolus prior to the a.m. feeding. The dose of lipid during the pre-partum period was 250 g/d, whereas the amount of lipid supplemented post partum was adjusted to the level of intake, approximately 0.92% of the previous days dry matter intake. Ex-vivo analyses of immune competence were measured including the antimicrobial activity of whole blood against Escherichia coli, Salmonella typhimurium and Candida albicans as well as the production of interferon-gamma by peripheral blood mononuclear cultures. At 7 days in milk cows were infused with 100 microg of Esch. coli lipopolysaccharide into one rear quarter. Supplementing fish oil increased plasma concentrations of eicosapentaenoic and docosahexaenoic acids, but had no affect on the proportions of arachidonic acid at calving. Fish oil did not influence the production of interferon-gamma or the antimicrobial activity of whole blood against any of the microorganisms. Furthermore, fish oil had no ameliorative effect on either the local or the systemic acute phase response following an intramammary lipopolysaccharide challenge in early lactating Holstein cows. Supplementing fish oil in the diet of peri-partum cows will not protect them from deleterious effects of an excessive acute phase response.

Desempenho e digestibilidade de novilhos zebuínos confinados recebendo leveduras vivas e monensina

EnglishThe effect of adding live yeast culture (Saccharomyces cerevisiae, strain 1026), monensin or the combination of both additives to high grain diets on feedlot performance and digestibility of steers, was studied. Nellore steers (n= 72, 339 kg BW, 20 months-old) were fed for 84 days a basal ration (2.58 Mcal EM/kg DM, 14% CP) without additives (control), or with yeast culture (0.6 g Beef Sacc®/ kg DM), monensin (0.3 g Rumensin®/ kg DM) or the combination of both additives to evaluate feedlot performance through individual measurements of dry matter intake, average daily gain and ultra-sound scanning of carcass subcutaneous fat thickness upon Longissimus (12 th rib) and Biceps femoris muscle and rib eye area. Other four steers were randomly allotted to one of the treatments in a 4 x 4 latin square design in order to assess digestibility of dry matter, crude protein, neutral detergent fiber and acid detergent fiber fractions of the diet. There were no effects of additives on dry matter intake and rate of growth of carcass fat thickness and rib eye area. Yeast culture tended to decrease average daily gain and increase feed conversion (p0.10). Supplementation of live yeast culture, monensin or the combination of both may not be important on finishing beef steers fed high grain diets in feedlot. portuguesFoi avaliado o efeito da adicao de cultura de leveduras vivas (Saccharomyces cerevisiae, cepa 1026), da monensina e da combinacao dos dois aditivos em dietas de alto concentrado, sobre as caracteristicas de desempenho de novilhos confinados e sobre a digestibilidade aparente da dieta. Novilhos Nelore (339 kg PV, 20 meses de idade, n= 72) foram alimentados por 84 dias com uma dieta basal (2,58 Mcal EM/kg MS, 14% PB) sem aditivos (controle) ou suplementada com levedura (0,6 g de Beef Sacc®/kg de materia seca), monensina (0,3 g de Rumensin®/kg de materia seca) ou a adicao de ambos aditivos para avaliar o desempenho em confinamento por meio da mensuracao individual do consumo, ganho de peso e medidas de ultra-som da espessura de gordura subcutânea nos musculos Longissimus (12a costela) e Biceps femoris. Outros quatro novilhos foram designados aleatoriamente aos tratamentos seguindo um delineamento em quadrado latino a fim de determinar os efeitos dos tratamentos sobre a digestibilidade aparente da materia seca, proteina bruta, fibra em detergente neutro e acido da dieta. Nao houve efeitos dos aditivos sobre o consumo de materia seca e na taxa de aumento da espessura de gordura subcutânea e em area do musculo Longissimus, entretanto, a levedura tendeu a diminuir o ganho de peso medio diario e aumentar a conversao alimentar (p0,10). A adicao de leveduras vivas, monensina ou da combinacao de ambos pode nao ser impor- tante sobre a terminacao de bovinos de corte confinados com dieta de alto concentrado.

Accuracy, precision and robustness of different methods to obtain samples from silages in fermentation studies

The objective of this study was to evaluate accuracy, precision and robustness of two methods to obtain silage samples, in comparison with extraction of liquor by manual screw-press. Wet brewery residue alone or combined with soybean hulls and citrus pulp were ensiled in laboratory silos. Liquor was extracted by a manual screw-press and a 2-mL aliquot was fixed with 0.4 mL formic acid. Two 10-g silage samples from each silo were diluted in 20 mL deionized water or 17% formic acid solution (alternative methods). Aliquots obtained by the three methods were used to determine the silage contents of fermentation end-products. The accuracy of the alternative methods was evaluated by comparing mean bias of estimates obtained by manual screw-press and by alternative methods, whereas precision was assessed by the root mean square prediction error and the residual error. Robustness was determined by studying the interaction between bias and chemical components, pH, in vitro dry matter digestibility (IVDMD) and buffer capacity. The 17% formic acid method was more accurate for estimating acetic, butyric and lactic acids, although it resulted in low overestimates of propionic acid and underestimates of ethanol. The deionized water method overestimated acetic and propionic acids and slightly underestimated ethanol. The 17% formic acid method was more precise than deionized water for estimating all organic acids and ethanol. The robustness of each method with respect to variation in the silage chemical composition, IVDMD and pH is dependent on the fermentation end-product at evaluation. The robustness of the alternative methods seems to be critical at the determination of lactic acid and ethanol contents.