The goal of the present study was to characterize the growth of body parts and composition of the growing empty body to infer how these aspects relate to the long-term growth of goat wethers from dairy breeds. Animals were slaughtered at several ages from birth to maturity (≅900 days old). All body parts were weighed and sampled to determine chemical constituent dry matter, crude protein, crude fat, ash and specific energy. The monomolecular (Brody), Gompertz, and Richards models, a biphasic model formed by the combined Brody and Gompertz functions, and a simple linear model were fitted to the growth profiles with different variance functions and were all evaluated using likelihood-information criteria. The effect of breed (genotype) was accounted for in all models but the resulting models were not more likely than the models without the breed effect. Remarkable differences were observed regarding inflection points, growth rates and trends for all body parts and chemical constituents of the body. The biphasic model did not supplant the monomolecular, Gompertz, Richards or the linear model in terms of likelihood-information criteria. Therefore, body parts and chemical constituents of the empty body presented monomolecular, sigmoid and linear time-trends. The growth profiles of fat, protein and energy of the empty body did not scale isometrically with the empty body proper. In addition, the variance was heteroscedastic along the time scale and was better represented by both an exponential variance over time or by a power function of the mean.

Forage sorghum (FS) (Sorghum bicolor (L.) Moench) is a key feed source for ruminants owing to its high yield and drought tolerance. The present paper assessed the agronomic characteristics, silage quality, intake and digestibility of five new Brazilian sorghum cultivars (BRS Ponta Negra variety, BRS 655 hybrid, BR 601 hybrid, BRS 506 variety and BRS 610 hybrid). Forages were grown (randomized complete block design) in a typical Brazilian north-eastern semi-arid climate, irrigated with 267 mm water, harvested as plants reached the soft dough stage of grain maturity and ensiled under laboratory and farm conditions. Apparent digestibility of the silages was determined using 25 Santa Inês lambs. BRS 506 outperformed the other cultivars in dry matter (DM) and digestible DM yields/ha. BRS 506 exhibited the lowest neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents and the highest in vitro dry matter digestibility (IVDMD) of the cultivars examined. BRS 655 produced the lowest level of lactic acid and the highest pH and ammonia-N concentration. There was no difference in intake or digestibility of DM among cultivars. Silages produced from BRS Ponta Negra resulted in higher crude protein (CP) intake than BRS 655. Silages made from BRS 506 and BRS Ponta Negra resulted in a greater digestibility of CP than those produced from BRS 655. Intake of NDF in silages generated from BRS Ponta Negra and BRS 610 was higher than that found in other cultivars. Although an average Brazilian North-eastern FS exhibited similar characteristics to other cultivars grown in dry regions around the world, the results indicated that BRS 506 had a yield advantage and higher nutritive value under Brazilian semi-arid conditions as compared to the other cultivars examined.

Animal slurry is separated in order to avoid excessive nitrogen, phosphorus and potassium (NPK) fertilization of crops in the field. To enhance fertilizer efficiency further, slurry and its separation products may be acidified, for instance in animal houses. The current study quantified the effects of these treatments, both individually and in combination, on fertilizer efficiency, energy production and heavy metal accumulation as a result of manure management. Acidification increased the availability of N to plants in the manure applied, and provided a better match between plant-available NPK in the manure and separation fraction applied to fields and crop need. Total biogas production was not affected by separation, whereas acidification reduced biogas production because the process was inhibited by a low pH and a high sulphur concentration. The amount of copper applied per hectare in the liquid manure to the wheat field was lower than the amount taken up and more zink and copper was applied in the solid fraction to maize field than taken up. The transportation and field application of solids and liquids did not increase management costs when compared to the transportation of slurry alone, but the investment and running costs of separators and manure acidification increased overall management costs.

A comparative study of the effect of dietary nitrogen (N) content [Low: 11·0; Medium-Low (MLow): 16·7; Medium-High (Mhigh): 23·1; High: 29·2 N g/kg dry matter (DM)] on apparent digestibilities, rumen fermentation and N balance was conducted in coarse wool Tibetan sheep and Gansu Alpine fine-wool sheep at Wushaoling in the northeast of the Qinghai-Tibetan Plateau. It was hypothesized that responses would differ between breeds and that responses would favour Tibetan over fine-wool sheep at low N intakes. Eight wethers [four Tibetan sheep and four fine-wool sheep, 20–24 months old; body weight ± standard deviation was 52 ± 3·2 kg] were used in two concurrent 4 × 4 Latin square designs. Dry matter, organic matter, neutral detergent fibre and acid detergent fibre digestibilities were higher in Tibetan than fine-wool sheep when fed the Low, MLow and High N diets while N retention was higher when the animals were fed the Low and MLow N diets. Tibetan sheep had a higher rumen pH than fine-wool sheep; however, total volatile fatty acids were similar between breeds. Molar proportions of acetate were higher but propionate and butyrate lower in Tibetan than fine-wool sheep. In addition, Tibetan sheep had higher concentrations of ruminal free amino acid-N and soluble protein-N than fine-wool sheep. Plasma and saliva urea-N concentrations were higher in Tibetan than fine-wool sheep when supplied with the Low N diet. It was concluded that Tibetan sheep were better able to cope with low N feed than fine-wool sheep because of the higher N retention and higher DM and fibre digestibilities with Low and MLow diets.