Manuela Silva Libânio Tosto

In vitro rumen fermentation kinetics of diets containing oldman saltbush hay and forage cactus, using a cattle inoculum

The aim of this experiment was to evaluate, by means of the semi-automated in vitro gas production technique, fermentation kinetics of carbohydrates and degradability of dry matter (DM) and organic matter (OM) of diets containing oldman saltbush hay levels (8.4; 18.8; 31.2 and 48.3%) associated to forage cactus in natura. Pressure readings of the gases were done with a pressure transducer at 2, 4, 6, 8, 10, 12, 17, 20, 24, 28, 34, 48, 72 and 96h post-inoculation. The rumen kinetics was described by the following parameters: maximum potential of gas production, lag time and production rates of gas (k), fibrous carbohydrates (FC) and non-fibrous carbohydrates (NFC). It could be observed that the addition of oldman saltbush hay to the diets promoted a quadratic effect in the production of gases originated from NFC. However, there was no significant effect on the production of gases originated from FC and on production rates of gases from NFC and FC. The degradability of DM and OM did not differ due to the addition of oldman saltbush hay. The use of 8.4% hay and 74.9% forage cactus promoted the maximum potential of production of gases from the fibrous fraction of diets containing cactus and oldman saltbush hay.

Análise econômica da utilização de silagens de cana-de-açúcar tratadas com ureia e óxido de cálcio sobre a produção de leite bovina

This aimed to evaluate the economic viability of diets containing four sugar cane silages: without additive, with 1% urea, with 0.5% CaO + 0.5% urea and ; with 1% CaO. Eight crossbred cows (Holstein x Gir) were used, arranged in two 4 x 4 Latin squares compounds of the: four diets, four animals and four periods. The sugar cane used was the variety SP 79-1011, with a yield of 140 t/ha/year in the third cut. The cut of sugar cane was done manually and the cana disintegrated in stationary chopper. The production costs of the roughage, concentrated and total diet were analyzed of the according to the prices of the local market, it was also estimated the EOC (effective operational cost). The diet containing silage sugar cane with 1% urea was less efficient because low consumption and resulted in greater weight loss of cows may affect milk production and body condition score of cows during the lactation period.

A comparative study on the excretion of urinary metabolites in goats and sheep to evaluate spot sampling applied to protein nutrition trials

The main objective of this study was to establish a protocol to validate urine spot samples to estimate N excretion and microbial synthesis in goat and sheep; and to study factors that affect daily creatinine and purine derivatives (PD) urinary excretion. Also a performance trial was carried out to compare goat and sheep slaughtered after different feedlot periods. Twelve Boer goats (20.6 kg ± 3.4 initial BW) and 12 Dorper sheep (18.4 kg ± 2.3 initial BW), all 4-mo-old, males, were used. Eight animals (4 goats and 4 sheep) were randomly allocated to be slaughtered at 28, 56, and 84 d in feedlot. The experiment was conducted in a completely randomized design in a 2 × 3 factorial scheme, in which the factors were both species and the 3 feedlot periods. Diet consisted of 50% sorghum silage and 50% concentrate on a DM basis. Nutrient intake was higher (P < 0.01) for sheep than goats. Apparent digestibility of nutrients was similar (P > 0.05) in both species. Sheep had greater (P < 0.01) ADG and final BW than goats. Fat deposition and fat:muscle ratio was higher (P < 0.01) in sheep carcasses. Sheep had higher N urinary (P = 0.02) excretion and N retention (g/d; P < 0.01) than goats. Urinary N excretion increased linearly (P < 0.01) in response to feedlot period. However, feedlot did not affect (P = 0.20) N retention, but linearly reduced the relationship between N retained and ingested (P = 0.04) or apparently digested (P < 0.01). Microbial efficiency (P > 0.05) did not differ between species. Creatinine excretion (C mg/d; P < 0.01) was higher in sheep than goats. Purine derivatives (Ŷ) were related closely with OM intake (Ŷ = 0.013±0.0007X; r2 = 94). A difference (P < 0.01) was found between the allometric model for creatinine excretion (Ŷ) and muscle weight (X) for both species, and the following equations were obtained: Ŷ = 89.04(±31.44)X0.9797(±0.16) for goats and Ŷ = 109.8(±47.50)X0.8002(±0.20) for sheep. Creatinine concentration was greater during nocturnal than diurnal periods, with lower diurnal fluctuations. Sampling time did not affect (P = 0.27) the PD:C ratio. The urea (U):C ratio was higher (P < 0.01) in sheep than goats, and was also higher (P < 0.01) during diurnal than nocturnal sampling periods. Our results suggest that it is necessary to take 2 and 3 spot urine samples after feeding to estimate N compounds excretions in goats and sheep, respectively.

Biomass turnover in brachiaria cultivars in a tropical environment

The experiment was conducted to evaluate the morphogenetic traits of three Brachiaria cultivars (common, Llanero and Tupi) subjected to continuous grazing with variable stocking rate in the four seasons of the year. A randomized block design with five replicates was adopted. Tissue turnover evaluations were carried out in the summer, fall, winter and spring, with measurements taken every two days. Stem length and the length of each green leaf were measured. With these determinations, the following variables were calculated: stem elongation rate (cm/tiller/day), leaf elongation rate (cm/leaf/day), number of live leaves per tiller and phyllochron (days/leaf). The highest leaf appearance rate was obtained by Tupi grass in the summer, and the lowest by Llanero grass in the winter. The lowest phyllochron, 5.90 days/leaf, was obtained by Tupi grass in the winter, whereas in commercial cultivars Llanero and common the average phyllochron was 9.04 and 10.04 days/leaf, respectively. Because of the effect of the transition from the dry season to the beginning of rains in the summer, this was the period of greatest variations in results among the different cultivars. Llanero grass stood out for the highest values for plant, tiller and leaf lengths, resulting from greater stem and leaf elongation rates. Tupi grass had the worst performance of all cultivars.