Rumen micro‐organisms are capable of producing microbial protein from ammonia and carbon skeleton, and non‐protein nitrogen (NPN) may be one of the sources of ammonia. Alternative source of NPN is the slow release of ammonia sources in which the product is the extrusion of starch with urea. This work aimed to determine the effects on nutrient intake, ingestive behaviour, digestibility, nitrogen balance, ruminal pH, rumen ammonia nitrogen, volatile fatty acids (VFA) and blood parameters with increased levels of extruded urea (50, 60, 70 and 80 g/100 kg of body weight [BW]) in beef cattle diet. Four rumen cannulated crossbred steers with initial mean weight of 336 ± 47 kg in a 4 × 4 Latin square design were distributed. Diets were formulated with 400:600 g/kg roughage:concentrate ratio on dry matter based and provided once per day, being used whole corn silage as roughage. There were no effects on nutrient intake (kg/day), ingestive behaviour, apparent digestibility, nitrogen balance, volatile fatty acid (VFA) and blood parameters in extruded urea treatment groups. Similar results were observed on time spent on feeding, rumination and idleness. There were positive linear effects (p = 0.022) on rumen pH in the time of 8 hr after feeding and also on plasma concentration of the extruded urea levels (p = 0.039); whereas a linear negative effect (p = 0.030) was observed on ammonia nitrogen for the collection time of 2 hr after feeding. Increased levels of extruded urea could maintain nutrient intake, digestibility, ingestive behaviour, rumen pH and blood parameters in normal conditions. In conclusion, we recommend the extruded urea use with values up to 80 g/100 kg BW in confined beef cattle that receive balanced diets with 140 g/kg of crude protein.

The objectives of the present study were to estimate dry-matter intake and output of faeces using two external and four internal markers in sheep fed Brachiaria brizantha cv. Marandu on an ad libitum basis over 3- and 5-day periods. Six sheep fitted with ruminal cannulas were randomly assigned in a crossover design experiment to receive either of two treatments of external markers, namely titanium dioxide (TiO2) and chromic oxide (Cr2O3). Faecal output was obtained by total faecal collection and faecal grab sampling. Faeces were collected for 3- or 5-day periods, and, for each collection period, two sampling methods were compared; grab samples were collected directly in the rectum once daily, and a second sample was taken at the same time directly in faecal collection bags after having determined the daily total output of faeces. Faecal concentrations of the internal markers, indigestible dry matter, indigestible neutral detergent fibre, indigestible acid detergent fibre and indigestible acid detergent lignin (iADL), were determined. Faecal output was not accurately predicted with indigestible dry matter, indigestible neutral detergent fibre, indigestible acid detergent fibre and iADL. Dry-matter intake was predicted with iADL and TiO2 when faeces were collected for 5 days as grab samples once daily, or as total collection and with Cr2O3 when faecal grab samples were collected for 5 days. The results using external markers indicated that TiO2 is not a marker equivalent to Cr2O3 for estimating intake and faecal output. TiO2 was the only external marker to accurately estimate faecal output, independent of the method (total or grab) and time period (3 or 5 days) used; this suggests that TiO2 is the best marker tested for predicting the faecal output of sheep that are fed a diet of fresh Brachiaria brizantha (cv. Marandu) grass ad libitum.

This study aimed to identify the best green-leaf offerings of Urochloa brizantha cv. Marandu for pasture-finished lambs receiving protein-energy supplementation at the rate of 1.6% of their body weights (BW). The animals were assigned into four treatments, which consisted of varied green-leaf offerings, namely, 105, 90, 75, or 60 g of dry matter/kg of body weight (BW). Sixty-eight contemporary Texel × mixed-breed lambs with an average initial BW of 22.6 kg were used over two years of experiment. The experiment was set up in a completely randomized design, the data were evaluated by analysis of variance and the means were compared by Tukey's test at the 0.05 significance level. There was no significant effect of year neither interaction of year with green-leaf offer. There were significant effects of leaf offer on dry matter intake (DMI) with behavior of positively linear (p<0.05). There were significant effects of green-leaf offer on final BW and average daily gain, and lambs receiving of 75 g/kg green-leaf offer showed the highest ADG (179 g/d). There were no significant differences in the carcass, meat, and primal cuts between the groups of lambs receiving different herbage offerings. There were significant effects of leaf offer on slaughter weight, hot carcass weight, and subcutaneous fat thickness. Lambs receiving of 75 g/kg leaf offer showed the highest SFT (5.8 mm). Slaughter weight and hot carcass weight averaged 41.52 kg and 20.07 kg, respectively. We recommend the treatment with leaves offer of 75 g/kg BW of Marandu pasture for the finishing of lambs supplemented at 1.6% of BW.

SUMMARYThe objective of this study was to evaluate the effects of two protein levels in mineral-proteinenergy supplements on the productivity and economic performance of Nellore steers. Ninety animals weighing 382.35±32.95 kg on average, were treated with mineral-nitrogen supplements containing 30% crude proteins (CP; 75% ground maize, 8.91 % urea and 16.09% mineral) and 40% CP (66.67 % ground maize, 11.90% urea, and 21.43% mineral). The animals were housed in two paddocks of Uruchloa brizantha 'MG-5' (syn. Brachiaria brizantha) and were weighed at the beginning, at 45 days, and at 94 days of the experiment, when they were slaughtered at an average weight of 451±35.38 kg. We evaluated supplement intake, weight gain and economic aspects. The 40 and 30% CP treatments significantly affected supplement intake (P<0.05), with averages of 0.69 and 2.26 kg/day, respectively. The average total weight gain was higher (P<0.01) in animals receiving the supplement containing 30 % CP (71.46 kg / animal) than in animals receiving 40% CP (64.33 kg/animal). Greater slaughter weight was attained in the animals treated with 30% CP (456.66 vs. 443.84 kg). The mineral-nitrogen supplementation in both CP levels provided satisfactory animal performance and carcass characteristics.Owing to economic considerations, it is recommended to use 40% CP mineral-nitrogen supplements on finishing steers on pasture, although success in reducing production costs of livestock ultimately depends on the variations in prices between the different regions of the country and market opportunities. Keywords:Brachiaria

Based on the assumption that the time required by the lamb to reach a certain weight at slaughter (slaughter weight) is partially dependent on the amount of milk ingested during suckling, and on the dietary management of the sheep and lamb. Our study proposes to examine the effects of the weaning system on the productive and reproductive performance of ewes supplemented with creep-feeding during grazing on Marandu pastures with their lambs and weaned at two different ages (60 and 90 days). Ewes were divided into two treatment groups (weaning ages) according to birth type (single or twin), in two consecutive years. The experimental period was the time from lambing to weaning. Data were evaluated by analysis of variance and means were compared by Tukey's test at the 0.05 significance level. There was no effect of year of observation on the parameters measured. Ewes did not show any differences in age and weight at lambing, weight at weaning, weight change, or time return to estrus. The average weight loss was 6 kg and the average time to return to estrus was 49 days. The highest averages for weaning weight (23.25 kg) and total weight gain (19.37 kg) of lambs, and lamb weight-to-ewe weight ratio (51.84%) were observed in weaning at 90 days of age. Body condition score and worm egg count per gram of feces of ewes were not affected by the treatments. The reproductive and productive performance of sheep on tropical pastures is not affected by the weaning system. It is recommended to conduct weaning at 90 days to obtain a better performance of lambs.