Abstract The objective of the meta-analysis was to evaluate the effects of beef cows weight variation during the 2nd and / or 3rd trimester pregnancy on some parameters of the progeny carcass. The cow weight gain during this gestational period was calculated to standardize the treatments: moderate loss (ML= cows that lost 0 to 5 % of weight) and moderate gain (MG= cows that gained 0 to 5 % of weight). The effect size for all parameters was calculated as medium difference (MD) with a 95% confidence interval and heterogeneity determined using the Q test and the I2 statistic. A random effects meta-analysis was performed for each indicator separately as the medium control and experimental groups. The cow’s weight variation during the studied time variation did not influence the progeny carcass characteristics (P>0.05). Although, a trend towards greater hot carcass weight (P=0.15) and thickness of subcutaneous fat (P=0.10) was observed in calves from MG cows in relation to calves from ML cows. However, the meta-analysis demonstrated that small variations in cow weight during the final half of pregnancy do not affect progeny carcass characteristics.

Resumen El objetivo del meta análisis fue evaluar los efectos de la variación del peso de vacas de carne durante el 2º y/o 3º trimestre de gestación en algunos parámetros de la canal de la progenie. La ganancia de peso de la vaca durante este período gestacional se calculó para estandarizar los tratamientos: pérdida moderada (PM= vacas que perdieron de 0 a 5 % de peso) y ganancia moderada (GM= vacas que ganaron de 0 a 5 % de peso). El tamaño del efecto para todos los parámetros se calculó como la diferencia de medias (DM) con un intervalo de confianza del 95 % y la heterogeneidad se determinó utilizando la prueba Q y el estadístico I2. Se realizó un meta análisis de efectos aleatorios para cada indicador por separado como grupo de control medio y experimental. La variación del peso de la vaca durante la variación de tiempo estudiada no influyó en las características de la canal de la progenie (P>0.05). Aunque se observó una tendencia hacia un mayor peso de la canal caliente (P=0.15) y del grosor de la grasa subcutánea (P=0.10) en terneros de vacas GM en relación con terneros de vacas PM. Sin embargo, el meta análisis demostró que las pequeñas variaciones en el peso de la vaca durante la mitad final de la gestación no afectan las características de la canal de la progenie.

Objetivou-se avaliar os parâmetros produtivos das pastagens de milheto (Pennisetum glaucum (L.) R. BR) e capim sudão (Sorghum bicolor cv. sudanense) submetidas ao pastejo contínuo de vacas destinadas ao abate. O delineamento experimental foi o inteiramente casualizado com dois tratamentos e três períodos, sendo cinco repetições (área). Os parâmetros produtivos das pastagens foram similares na comparação entre os tratamentos (P<0,05). O ciclo vegetativo das pastagens não alteraram a massa de forragem (1.606,93 kg e 1.617,47 de matéria seca (MS)/ha) e a oferta de forragem (9,42 e 8,29 kg de MS/100 kg de PV) das pastagens de milheto ou capim sudão. No entanto, as médias para taxa de acúmulo de matéria seca e proteína bruta demonstraram maiores valores nos primeiros 21 dias de utilização das pastagens (130,77 kg de MS/ha e 17,04 g/kg de MS), seguidas de reduções nos dois últimos períodos, sendo as médias do segundo período (65,53 kg/ha de MS e 12,96 g/kg de MS) superior à do terceiro período experimental (36,13 kg/ha de MS e 10,01 g/kg de MS). Os valores para fibra em detergente neutro foram similares nos dois períodos iniciais (48,81; 49,01 g/kg de MS), seguida de aumento nos últimos 21 dias de utilização das pastagens (56,54 g/kg de MS). A taxa de lotação em kg/ha de PV demonstrou interação entre tratamento e período; no entanto, os valores médios entre os tratamentos foram similares (1741,1 kg/ha de PV para milheto e 1881,7 kg/ha de PV para sudão). Pastagens de milheto ou capim sudão se equivalem em relação às características produtivas, sob sistemas de pastejo contínuo com vacas de descarte.

This study aimed to evaluate the productive parameters of pearl millet (Pennisetum glaucum (L.) R. BR) and Sudan grass (Sorghum bicolor cv. Sudanense) pastures, under continuous grazing by cows destined to slaughter. We used 22 crossbred Charolais and Nellore cows, kept under continuous grazing on Sudan grass or pearl millet pastures, over 63 experimental days, divided into three periods (21 days each). The experimental design was completely randomized with two treatments and three periods, with five replicates (area). The productive parameters of the pastures were similar when treatments were compared (P < 0.05). The growing cycle of pastures did not affect forage mass (1617.47 and 1606.93 kg of dry matter (DM)/ha) and forage offer (9.42 and 8.29 kg of DM/100 kg BW) on pearl millet or Sudan grass pastures. However, the average rate of accumulation of dry matter and crude protein showed higher values on the first 21 days of pasture use (130.77 kg DM/ha and 17.04 g/kg DM), followed by reductions in the last two periods, and the averages of the second period (65.53 kg DM/ha and 12.96 g/kg DM) were higher than those of the third experimental period (36.13 kg DM/ha and 10.01 g/kg DM). The values for neutral detergent fiber were similar in the two earlier periods (48.81, 49.01g/kg DM), followed by an increase in the last 21 days of pasture use (56.54 g/kg DM). The stocking rate in kg/ha of BW showed an interaction between treatment and period, however, the mean values were similar between treatments (1741.1 kg/ha of the BW for pearl millet and 1881.7 kg/ha of BW for Sudan grass). The average daily live weight gain did not differ between treatments (1.04 for pearl millet and 0.96 for Sudan). The average daily gain per area (4.18, 4.55 kg/ha of BW) was similar on the first 42 days of pasture use and higher than on the last 21 experimental days (2.39 kg / ha of BW). Pearl millet or Sudan grass pastures are equivalent with respect to the production characteristics under continuous grazing by culling cows.

Objetivou-se com este estudo avaliar os parâmetros comportamentais e as estratégias de deslocamento e alimentação de vacas de descarte em pastagens de milheto ou capim sudão. Os tratamentos consistiram em: pastagem de milheto (Pennisetum americanum (L.) Leeke) ou pastagem de capim sudão (Sorghum bicolor cv. sudanense), ambos tratamentos submetidos ao pastejo contínuo de vacas de descarte, ao longo de 63 dias experimentais, subdividido em três períodos. Foram utilizadas 20 vacas de descarte cruza Charolês x Nelore, de idade média de 8 anos e peso vivo médio inicial de 445 kg. Os animais foram distribuídos em 10 piquetes, sendo utilizados cinco piquetes para cada tratamento comportando duas vacas. As avaliações comportamentais foram realizadas durante 24 horas ininterruptas. O delineamento experimental foi inteiramente casualizado com 2 tratamentos e 3 períodos de avaliação. O tempo de pastejo das vacas apresentou interação (P=0,0035) entre tratamento e período, sendo o menor tempo destinado à atividade no primeiro período na pastagem de milheto (504 minutos) comparado com o segundo período desse mesmo tratamento (587 minutos) e terceiro período nas pastagens de capim sudão (535 minutos). Os tempos de ruminação e ócio foram semelhantes entre os tratamentos; no entanto, o de ócio diminuiu e o de ruminação aumentou com o avanço dos períodos. As espécies de forrageiras não influenciaram as variáveis relacionadas às estratégias de deslocamento e alimentação. Com o avanço do ciclo das pastagens, o número de passos por minuto, estações por minuto e por dia diminuíram enquanto a taxa de bocado e número de bocados por dia aumentaram. Os parâmetros comportamentais de vacas de descarte em pastagens de milheto ou capim sudão são similares; no entanto, o avanço do ciclo vegetativo dessas espécies proporciona modificações no padrão comportamental dos animais.

The objective of this study was to evaluate the behavioral parameters and strategies of displacement and feeding of cull cows grazing millet or sudan grass. The treatments consisted of: pearl millet (Pennisetum americanum (L.) Leeke) or sudan grass (Sorghum bicolor cv. Sudanense). Both treatments were submitted to continuous grazing of cull cows over 63 experimental days subdivided into three periods. Using 20 Charolais x Nellore cull cows, at the average age of 8 years and average weight of 445 kg. The animals were divided into 10 paddocks, five paddocks used for each treatment comprising two cows. The behavioral assessments were carried out for 24 hours straight. The experimental design was completely randomized with two treatments and three periods. The grazing time of cows showed interaction (P = 0.0035) between treatment and period, and the shortest time for the activity in the first period on pearl millet (504 minutes) compared to the second period of that same treatment (587 minutes) and the third period on sudan grass pastures (535 minutes). The times of rumination and idling were similar between treatments; however, the idling time decreased and rumination increased with time periods. The forage species did not affect the variables related to the strategies of displacement and feeding. With the advancement of cycle pastures the number of steps per minute, stations per minute and per day decreased while the bite rate and the number of bites per day increased. The behavioral parameters of cull cows grazing sudan grass or millet are similar; however, the advancement of the vegetative cycle of these species provides changes in the behavioral pattern of the animals.

The objective of this study was to evaluate the effect of carbohydrate sources (corn, soybean hulls or wheat bran) in the diet on performance of feedlot steers in the finishing phase. Twenty-four Charolais × Nellore crossbred steers, aged 22 months and initial weight of 335.0±10.9 kg were used in the experiment. Diets contained 40% sorghum silage and 60% concentrate. The intakes of dry matter (DM; 10.68, 10.16 and 10.34 kg/day) and crude protein (1.66, 1.70 and 1.72 kg/day) were not affected by diets with corn, soybean hulls or wheat bran, respectively. The intakes of neutral and acid detergent fiber were higher for soybean hulls, but the diet containing corn provided higher intake of non-fibrous carbohydrates, total digestible nutrients and digestible energy. Weight gain was higher and better feed conversion for animals fed corn (1.57 kg/day, 6.85 kg DM/kg gain) or soybean hulls (1.58 kg/day and 6.61 kg DM/kg gain) compared with steers receiving wheat bran (1.29 kg/day and 8.14 kg DM/kg gain) in the diet. There was no significant effect of carbohydrate sources on the final body score (3.78 points), energy conversion (28.25 Mcal digestible energy/kg gain), hot carcass yield (57.63 kg/100 kg BW) and fat thickness (3.1 mm). From an economic point of view, soybean hulls can be an alternative source of carbohydrate to corn in diets of finishing steers with 60% concentrate.

The response of energy supplementation was evaluated on the development and reproductive performance of beef heifers on temperate grasslands. Twenty-eight Charolais × Nellore heifers, with initial average age of 18 months and initial live weight of 274.9 kg were utilized. The animals were maintained on oat + ryegrass pasture and distributed in the following treatments: no supplementation (NS): heifers kept exclusively on pasture; MEG: supplementation with protected fat Megalac®; BRM: supplementation with brown rice meal; BRM+MEG: supplementation with BRM + protected fat. The average final weight of the heifers was of 403.4 kg and corresponded to 89.5% of the adult weight. The body condition of heifers increased linearly with daily increase of 0.012 points, correlating positively with the final weight. There was interaction between treatment and period for average daily weight gain. The highest daily weight gain, 1.395 kg, occurred in the first period when the animals were supplemented with BRM+MEG. In the last period, the NS animals presented the lowest daily weight gain, 0.888 kg. Supplementation with brown rice meal and/or protected fat does not interfere in the intake of pasture by heifers or increase the total intake of dry matter, not changing, therefore, the average daily weight gain at the end of the period of grazing. The daily weight gain does not change during supplementation. The use of temperate pasture with and without supplementation promotes the proper development of the structure and reproductive tract of heifers, benefiting the animal performance indexes in the first mating at 25-27 months of age.

Production parameters of intercropped pastures of oat and rye grass managed with beef heifers supplemented with brown rice meal and/or protected fat were evaluated. Twenty-eight Charolais × Nellore crossbred heifers at initial average age of 18 months and initial average live weight of 274.9 kg were utilized in the experiment. Animals were kept on oat + rye grass pastures and distributed in the following treatments: no-supplementation (NS): heifers kept only in pastures; Megalac (MEG): supplementation with protected fat; brown rice meal (BRM): supplementation with BRM; BRM + MEG: supplementation with BRM plus protected fat. The greater participation of oat leaf was from July 5th to August 10th, 2009 and of rye grass, from August 30th to September 26th, 2009. The crude protein content increased until the 55th day (225.1 g/kg). Pasture total digestible nutrients presented a cubic behavior, with an average of 722.0 g/kg. The highest supply of leaf blades, 5.17 kg of dry matter/100 kg of live weight, was found in the second period. Pasture intake increased throughout the periods. Forage mass and support capacity of the animal did not differ between treatments, presenting means of 1245.02 kg of dry matter/ha and 882 kg of live weight/ha, respectively. Stoking rate, forage loss and pasture intake were not affected by the treatments. Supplementation of beef heifers with rice meal and/or protected fat did not change production parameters of oat + rye grass pastures or pasture intake. Increase in daily accumulation rate of dry matter and supporting capacity of the animals increases forage losses.

The objective of this study was to evaluate behavior patterns of heifers grazing on black oat (Avena strigosa Schreb.) and ryegrass (Lolium multiflorum Lam.), fed supplementation with brown rice meal and/or protected fat. A total of 28 Charolais × Nellore crossbred heifers at average initial age of 18 months and with initial live weight of 274.9±4.97 kg were used in the experiment. Animals were kept in oat + ryegrass pastures and distributed in the following treatments: no supplementation; Megalac (MEG): protected fat supplementation; supplementation with brown rice meal (BRM); and supplementation with BRM + MEG. The neutral detergent fiber (NDF) intake of pasture either in kg or in percentage of live weight was not changed by supply of supplement, but increased linearly (0.045 kg per day) over grazing periods. Supplementation with BRM and BRM + MEG reduced grazing time, 49.63%, in relation to non-supplemented animals and animals supplemented with MEG, 63.13%. Feeding seasons per minute increased over the experimental period with reduction in time spent in each feeding station. The number of bites per feeding station decreased linearly, with a variation of 34.48% in the late grazing period. Heifers supplemented with BRM and BRM + MEG require less time for grazing and increase their idle time, with no modification in displacement patterns within the paddocks and pasture ingestion. Grazing and idle time does not change in the distinct periods of pasture use, but rumination time increases with days of pasture use and with increase in NDF intake.