Leilson Rocha Bezerra

Residual feed intake: a nutritional tool for genetic improvement

The goal of this bibliographical study was to provide information about residual feed intake (RFI), a new criterion used in the selection of beef cattle for growth rate, food ingestion, and feed efficiency. RFI is calculated as the difference between real consumption and the quantity of food an animal is expected to eat based on its mean live weight and rate of weight gain. In studies of RFI, many speculations are made among researchers about the reliability of this criterion. However, there is a high genetic correlation with characteristics related to post-weaning consumption and maturity, indicating that the biological processes that regulate consumption and efficiency in young animals are similar to the processes that regulate consumption and efficiency in animals of greater age. In contrast to feed conversion, selection based on RFI seems to select for lower rates of consumption and lower animal maintenance requirements without changing adult weight or weight gain. Therefore, we conclude that the data indicate that there are extraordinary benefits to be gained from changing the goals of selection from increased weight gain to improved nutritional efficiency. Given the importance of animal production for economic development in Brazil choosing the best selection goals for livestock improvement is essential. To include an index of feed efficiency in future goals would be desirable, and RFI may play a part in this if economic methods of implementation can be developed.

Carcass traits and meat quality of crossbred Boer goats fed peanut cake as a substitute for soybean meal

This study aimed to determine the impact of replacing soybean meal with peanut cake in the diets of crossbred Boer goats as determined by carcass characteristics and quality and by the fatty acid profile of meat. Forty vaccinated and dewormed crossbred Boer goats were used. Goats had an average age of 5 mo and an average BW of 15.6 ± 2.7 kg. Goats were fed Tifton-85 hay and a concentrate consisting of corn bran, soybean meal, and mineral premix. Peanut cake was substituted for soybean meal at levels of 0.0, 33.33, 66.67, and 100%. Biometric and carcass morphometric measurements of crossbred Boer goats were not affected by replacing soybean meal with peanut cake in the diet. There was no influence of the replacement of soybean meal with peanut cake on weight at slaughter ( = 0.28), HCW ( = 0.26), cold carcass weight ( = 0.23), noncarcass components of weight ( = 0.71), or muscularity index values ( = 0.11). However, regression equations indicated that there would be a reduction of 18 and 11% for loin eye area and muscle:bone ratio, respectively, between the treatment without peanut cake and the treatment with total soybean meal replacement. The weights and yields of the commercial cuts were not affected ( > 0.05) by replacing soybean meal with peanut cake in the diet. Replacing soybean meal with peanut cake did not affect the pH ( = 0.79), color index ( > 0.05), and chemical composition ( > 0.05) of the meat (). However, a quadratic trend for the ash content was observed with peanut cake inclusion in the diet ( = 0.09). Peanut cake inclusion in the diet did not affect the concentrations of the sum of SFA ( = 0.29), the sum of unsaturated fatty acids (UFA; = 0.29), or the sum of PUFA ( = 0.97) or the SFA:UFA ratio ( = 0.23) in goat meat. However, there was a linear decrease ( = 0.01) in the sum of odd-chain fatty acids in the meat with increasing peanut cake in the diet. Soybean meal replacement with peanut cake did not affect the n-6:n-3 ratio ( = 0.13) or the medium-chain fatty acid ( = 0.76), long-chain fatty acid ( = 0.74), or atherogenicity index values ( = 0.60) in the meat. The sensory attributes of the longissimus lumborum did not differ with the inclusion of peanut cake in the diet as a replacement for soybean meal. These results suggest that based on carcass and meat characteristics, peanut cake can completely substitute soybean meal in the diet of crossbred Boer goats.

Dietary supplementation for Santa Inês hair ewes on pasture at pre- and postpartum periods: dry matter intake, digestibility, milk production, and mineral metabolism

The aim of this study was to evaluate the impact of different levels of dietary supplementation and reproductive stages on dry matter intake, digestibility, milk production, and mineral metabolism in Santa Inês hair ewes. Two dietary supplement levels of 0.5 and 1.5%, based on body weight, were used. A total of 12 hair ewes (six subjected to 0.5 and six subjected to 1.5% of concentrate supplementation based on body weight—BW) of the Santa Inês breed were evaluated in a completely randomized design with fixed effects of supplementation level, period, and its interactions. Dry matter intake, digestibility, milk production, and mineral metabolism (calcium (Ca), phosphorus (P), magnesium (Mg), alkaline phosphatase (ALP), type I insulin-like growth factor (IGF-I), parathyroid hormone (PTH), and osteocalcin (OC)) were assessed. Dry matter digestibility was affected by the supplementation level (during both pregnancy and lactation), with higher values in ewes fed at a level of 1.5% of BW. A significant interaction between treatment × reproductive stages was found for the Mg concentration. A period effect (P < 0.05) on serum concentrations of P, Ca/P, Mg, and IGF-I was observed. Serum P concentrations were influenced (P < 0.05) by treatments and reproductive stages. There were significant differences in the Ca/P ratio among the reproductive stages. The enzymatic activity of ALP and serum IGFI differed among reproductive stages. Ewes supplemented at a level of 1.5% of BW produced 18.5% more milk than ewes supplemented at a level of 0.5% of BW. The use of 0.5% of body weight in concentrate supplementation is recommended for the reduction of production costs, without having an effect on the mineral metabolism of Santa Inês hair ewes.

Carnauba wax as a wall material for urea microencapsulation: Carnauba wax as a wall material for urea microencapsulation

BACKGROUND The high ureolytic activity of rumen microbiota is a concern when urea is used in ruminant feed, because it leads to fast urea conversion, resulting in possible intoxication and lower nitrogen utilization. This study intended to microencapsulate urea using carnauba wax to obtain slow-release systems in the rumen. The experiment was conducted in a randomized block design, arranged in a 3 × 2 factorial, with the urea encapsulated with carnauba wax in ratios of 1 : 2; 1 : 3, and 1 : 4 (UME 2; UME 3, and UME 4) and two particles sizes (small, PS ; and large, PL ). RESULTS All formulations showed excellent properties, including inhibition of urea hygroscopicity. The formulation UME 2 exhibited the greatest yield (91.6%) and microencapsulation efficiency (99.6%) values, whereas the formulation UME 4 presented the greatest thermal stability (259.5 °C) and lowest moisture content (1.81%). The UME 2 formulation presented a slower release than the other UME formulations studied. CONCLUSION The production of urea microspheres using carnauba wax was successful for all microencapsulated systems developed, evidencing the promising potential for use in ruminant animal diets. The UME 2 formulation with large particles is the most recommended because it permitted greater resistance to microbial attack, allowing a slower release of urea into the rumen, reducing the risk of intoxication or ruminal alkalosis.