Chemical Properties, Ruminal Fermentation, Gas Production and Digestibility of Silages Composed of Spineless Cactus and Tropical Forage Plants for Sheep Feeding.

The aim was to evaluate the chemical composition, carbohydrates, protein fractionation and in vitro gas production of silages composed of spineless cactus and tropical forages and their effect on sheep performance. Treatments consisted of silages: corn silage (CS), spineless cactus silage (SCS), spineless cactus + gliricidia (SCG), spineless cactus + buffel grass silage (SCBG) and spineless cactus + pornunça (SCP). Silos were opened 60 days after ensiling, and analyses were carried out. The digestibility test lasted for 36 days, with eight animals per treatment. A completely randomized design was adopted. Considering carbohydrate fractionation, CS, SCS and SCBG silages had higher total carbohydrate content (p = 0.001). The SCS silage presented a higher A + B1 fraction (p = 0.001). The SCBG and SCG silages showed a higher B2 fraction (p < 0.0001) compared to the CS and SCS silages. The SCBG and SCP silages presented a higher C fraction (p = 0.001). For protein fractionation, the SCP and SCG silages showed higher crude protein contents (p = 0.001). The CS and SCS silages showed a higher A fraction (p = 0.001). The SCBG silage presented a higher B1 + B2 fraction (p = 0.001). The SCG silage showed a higher B3 fraction (p = 0.006) compared to SCBG silage. The SCS and SCP silages showed a higher C fraction (p = 0.001). Exclusive SCS silage showed higher in vitro dry matter digestibility (p = 0.001), dry matter degradability (p = 0.001) and total gas production (p = 0.001). The use of the SCBG, SCP and SCG silages to feed sheep increased the dry matter intake (p < 0.001). Sheep fed the SCG silage showed greater dry matter and crude protein digestibility compared to the sheep fed the CS, SCS and SCP silages (p = 0.002). There was a higher water intake (p < 0.001) with the use of the SCS and SCG silages to feed the sheep. The SCP and SCG silages provided a greater intake (p < 0.001) and excretion (p < 0.001) of nitrogen by the animals. Although there were no differences between the treatments for daily gains, lambs that received the spineless cactus-based silage associated with tropical forages showed higher gains (160-190 g/day) than lambs that received CS silage (130 g/day). Thus, the use of spineless cactus associated with buffelgrass, pornunça and gliricidia to prepare mixed silages (60:40) to feed sheep has potential use to feed sheep, with positive effects on nutrient degradation and increases in dry matter intake. Under experimental conditions, we recommend the exclusive use of spineless cactus silage associated with buffel grass, pornunça and gliricidia in feeding sheep in semi-arid regions, as it provides nutrients, water and greater daily gains compared to corn silage.

Phenotypic plasticity and behavioral responses of dairy cattle on rotational grazing.

Heat stress is one of the most important environmental challenges faced by dairy cattle, with a deleterious effect on animal production and welfare. This research was conducted to evaluate the effects of the thermal environment on the physiological and behavioral responses of dairy cattle in a rotational picket. The research was conducted on an experimental farm, located in the Agreste region of the state of Pernambuco, Brazil. The animals were managed in a rotational picket system of signal grass, with an occupation and a rest period of 7 and 28 days, respectively, for a stocking rate of 3.2 AU ha-1. The determination of the effect of stressors on the animals was performed by recording the dry bulb temperature (°C), and the relative humidity, which allowed the characterization of the thermal environment by the temperature and humidity index and by the specific enthalpy (kJ kg-1). The physiological variables monitored were respiratory rate (mov. min-1), rectal temperature (°C), and skin temperature (°C). The behavioral responses quantified were activities, walking, ruminating, idling and ingestive behaviors, eating, and drinking, with the percentage of time spent on each activity being recorded. According to the canonical multivariate analysis, the chi-square test, and the variation of physiological patterns, the animals, even in a situation of greater thermal challenge, presented physiological responses within conditions considered normal; however, they reduced grazing activity (eating) during the hottest hours and increased the activities of rumination and idling.

Effect of association of fresh cassava root with corn silage in replacement for cactus cladodes on dairy cow performance.

The aim of this study was to investigate the replacement effect of cactus cladodes with cassava root and corn silage (CRCS) (0, 25, 50, 75, and 100%, dry matter basis) in diets of lactating dairy cows on nutrients intake and digestibility, microbial protein synthesis, nitrogen balance, and milk yield. Ten Holstein cows with an average milk yield of 16 kg/day, an initial body weight (BW) of 670 ± 35 kg, and an average of 17 weeks in milking were assigned to an experiment using a double 5 × 5 Latin square design. The ratio of forage/concentrate was 82:18, and the ingredients used were cactus cladodes, cassava root, corn silage, soybean meal, wheat meal, urea, and mineral premix. The intake of dry matter, organic matter, and total digestible nutrients were not influenced by the replacement levels. On the other hand, the intake of crude protein and neutral detergent fiber increased while the intake of non-fiber carbohydrates decreased with addition of CRCS. The digestibility of the nutrients was not changed as the milk yield as fat-corrected milk production and milk content of fat, protein, lactose, and total solids. The microbial protein synthesis, microbial protein efficiency, nitrogen balance, and efficiency of N in milk were not changed. Therefore, we recommend the complete replacement of cactus cladodes by cassava root and corn silage in the diets of lactating cows with an average milk yield of 16 kg/day.