Andressa Faccenda

Heat stress is a major challenge in tropical and subtropical dairy systems; however, limited evidence exists on how dietary lipid supplementation influences cow behavior, physiology, and milk quality under semi-confined summer conditions. This study evaluated the effects of different lipid sources (protected fat, flaxseed, and a mixture) on milk yield, composition, fatty acid profile, and behavioral and physiological responses of Holstein cows. Twelve cows were allocated to three 4 × 4 Latin squares, with each period lasting 15 days (10 days adaptation, 5 days data collection). Treatments consisted of a basal diet supplemented with 278 g protected fat, 790 g flaxseed, or a combination of 139 g protected fat and 395 g flaxseed, compared with a control. Behavioral observations, physiological parameters, and milk samples were collected. Results showed that daily thermal load indicated moderate thermal challenge, but behavioral and physiological responses remained within normal ranges. Milk yield and protein content were unaffected by lipid supplementation. Flaxseed significantly increased milk fat percentage and improved the fatty acid profile, with higher concentrations of unsaturated fatty acids, including omega-3 and CLA, compared with protected fat. Somatic cell count did not differ among treatments, indicating no adverse effect on udder health. Elevated milk urea nitrogen values suggested imbalances between protein and carbohydrate supply. Overall, flaxseed supplementation enhanced milk nutritional quality while maintaining production stability under moderate heat stress. These findings suggest that flaxseed may represent a practical nutritional strategy to improve milk value and support sustainable dairy management in warm climates.

The objective of this study was to evaluate effects of adding agro-industrial by-products (soybean hulls and cornprocessing residue) and bacterial inoculant to Tifton 85 forage at ensiling on nutritional quality and bacterial colonization of resulting silages. The design was completely randomized in a 3 × 2 factorial scheme, with 6 treatments and 4 replicates. Treatments were: Tifton 85 forage; Tifton 85 + soybean hulls; Tifton 85 + corn-processing residue; Tifton 85 + bacterial inoculant; Tifton 85 + soybean hulls + inoculant; and Tifton 85 + corn-processing residue + inoculant. Inclusion of by-products increased dry matter and organic matter percentages of silages, while addition of soybean hulls improved crude protein concentration in silage. Total digestible nutrients in silages containing by-products were higher than in straight Tifton 85 silage. In addition, addition of by-products increased in vitro dry matter and organic matter digestibilities of resulting silages. Most treatments showed aerobic stability up to 144 hours after exposure to air, except for Tifton 85 + corn-processing residue without inoculant, which became unstable by 120 hours of exposure. Addition of by-products at ensiling of Tifton 85 forage appears beneficial but there seems little benefit in adding bacterial inoculant. More studies on a larger scale are needed to confirm these preliminary results, while feeding studies would determine any improvement in animal performance when fed silage containing by-products.

The objective was to evaluate the microbiological quality of water and milk from agroecological and conventional properties in western Paraná. The collections were carried out in 20 conventional properties in the municipality of Santa Helena - PR, and in 27 agroecological bases and in Diamante d'Oeste and Ramilândia - PR. Milk collections were carried out in different production systems and seasons. Were analyzed the contamination of thermotolerant coliforms (ThermC), total coliforms (TC), enterobacteria, aerobic mesophiles (AM), determination of chemical composition, somatic cell count (SCC) and total bacterial count (TBC). There was no difference in milk composition between summer production systems. In relation to SCC during the winter, 44.4% and 55.0% of the properties presented values ​​above 600 thousand cells mL^-1, in the agroecological and conventional systems, respectively. In both seasons, most of the agroecological properties are above 600 thousand CFU mL^-1 of TBC. In both production systems and seasons, the AM values ​​were lower than those allowed by NI76, and there was no difference for enterobacteria in milk. The count of milk TC in winter was similar between the two production systems. For the water samples for cleaning the milking equipment, the TC and ThermC values were higher in the agroecological system. The use of management practices is recommended in order to reduce the SCC and TBC values ​​of milk produced in the western of Paraná to conform to the values required by NI76.

Background: Brewer's grains, a by-product of the brewery industry, can be included in the diet of ruminants. However, its high humidity makes it difficult to store and preserve. Objective: To evaluate the efficiency of sun dehydration of wet brewer’s grains (WBG) and the effect of storage period on its nutritional and microbiological quality. Methods: A completely randomized experimental design was used to evaluate WBG dehydration efficiency, with treatments corresponding to 0, 1, 2, 4, 6, 8, 10, 12, 14 and 16 hours of sun exposure. A second experiment was carried out using also a completely randomized design to evaluated the effect of storage with the following treatments: 0, 10, 20, 30, 60, 90, 120, 150 and 180 days of storage of the dry by-product. Results: Dry matter (DM) content linearly increased with dehydration period. The chemical composition of the dried brewer's grains had no effect as a function of storage period. Indigestible protein (C fraction) increased linearly but did not compromise the cumulative gas production and the in vitro digestibility of DM and protein. Storage time had no effect on fungus population. The maximum aflatoxin value was 45.5 μg/kg, and remained within acceptable limits for bovine feed. Conclusion: Dehydration of WBG in the sun is efficient to guarantee conservation and makes it possible to store the by-product. The storage of the dry by-product for 180 days does not compromise its nutritional or microbiological quality.

The objective of this study was to evaluate the effect of inclusion of condensed tannins (CT) from black wattle (Acacia mearnsii) on feed intake, ruminal protozoa population, ruminal fermentation, and nutrient digestibility in Jersey steers. Five ruminally-cannulated steers were used in a 5 × 5 Latin square design, with five periods of 20 days each (14 days for diet adaptation and six days for sample collection per period). Treatments were composed of dietary inclusion levels of condensed tannins at 0, 5, 10, 15, and 20 g/kg of diet dry matter. Intakes of dry matter, organic matter, ether extract, crude protein, neutral detergent fiber, and total digestible nutrients were not affected by condensed tannins. The ruminal pH was reduced linearly with tannin levels. Ruminal ammonia nitrogen concentration was not affected by tannins. Tannins reduced the molar proportion of acetate and did not affect the ruminal protozoal population, which might be related to the low doses used. Digestibilities of dry matter, organic matter, and neutral detergent fiber were not altered; however, there was a linear reduction in crude protein digestibility. Based on these results, CT extracts from black wattle are not recommended for improving nutrient utilization in steers at the tested levels.

The objective of this study was to evaluate the effects of five levels of condensed tannins (CT) from black wattle (Acacia mearnsii) in the diets of lactating dairy cows on intake, nutrient digestibility, ruminal microbial protein synthesis, milk production, composition, oxidative profile, and blood metabolites. Five Holstein cows (88 ± 26.8 days in milk) were allocated in a 5 x 5 Latin square design for a period of 20 days (14 days of diet adaptation and six for sampling). Treatments were the inclusion levels of CT at 0, 5, 10, 15 and 20 g/kg of dry matter (DM) in the diet. There was no effect of CT on DM intake. The digestibility of DM and neutral detergent fiber changed quadratically, with the maximum values at 12.2 and 11.4 g/kg of DM, respectively. There was no effect on ruminal microbial protein synthesis and milk production; however, milk casein concentration was reduced linearly. There was no effect on the milk oxidative profile. Inclusion of CT at levels up to 20 g/kg of DM did not affect intake or microbial protein synthesis; however, added CT depressed the production of energy corrected milk and milk casein concentration.

The objective of this study was to evaluate the nutritional quality of twenty-nine cultivars of sugarcane. The design was completely randomized, with twenty-nine treatments (cultivars) and three replicates. The evaluations were performed at 540 days after planting during the phenological stage of maturation of sugar cane. Stalk length, number of nodes per plant, internodes length and stalk diameter were evaluated. The stalk samples were crushed, pre-dried and ground for achievement of chemical analysis, carbohydrate fractionation and in vitro digestibility of dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF). Data were analyzed by analysis of variance and posteriorly submitted to Scott-Knott test at 5% probability. Regarding biometric measurements the cultivars differed (P0.05) in the number of nodes as well as in the average internode length and stalk diameter. The content of DM, OM, protein, ether extract, NDF and acid detergent fiber showed differences between the cultivars evaluated (P<0.05). Carbohydrate fractionation also differed between cultivars (P <0.05), being that cultivars RB86 7515, RB92 806 and RB03 6091 presented high fraction of rapidly degradable carbohydrates. The highest values of in vitro digestibility of DM and OM occurred for cultivars RB86 7515, RB92 579 and RB03 6091 (P<0.05). Considering the variables analyzed, the cultivars RB03 6091, RB92 579 and RB86 7515 showed greater concentration of rapidly degradable carbohydrates and greater in vitro digestibility of DM and OM demonstrating potential for use in ruminant feeding.

This study aimed to evaluate the nutritional value of legumes leucaena and desmodium preserved in hay and silage form. We used a completely randomized design in a 2x2 factorial arrangement with two bulky conservation methods (hay and silage) and two legumes (leucaena and desmodium). For the bulky characterization was determined chemical composition and total digestible nutrients (TDN). For assessing the nutritional value, analysis of in vitro dry matter digestibility (IVDMD) and cell wall digestibility (IVCWD), and in situ effective degradability of dry matter (EDDM) and crude protein (EDCP) were performed. Data were submitted to ANOVA and Tukey test at 5% probability. Due to the characteristics of each specie leucaena presented a higher crude protein (CP) and TDN content compared to desmodium and lower fibrous fractions. The IVDMD presented interaction between the conservation form and forage (P<0.05), where leucaena hay was higher than the others treatments. The IVCWD also presented interaction (P<0.05), and the best values were obtained for leucaena silage. EDDM was superior in leucaena compared to desmodium (P<0.05). Regarding the method of preservation, the EDDM was higher in hay compared to silage. For the EDCP there was an interaction between conservation method and forage, where leucaena silage and hay were similar (P<0.05), but higher than other treatments. Thus, leucaena has a nutritional value higher than desmodium and the conservation of legumes in the hay form presented a higher nutritional value to the conserved as silage.

The objective of this study was to determine the optimal level of dried brewers' grains (DBG) to replace soybean meal in diets for lactating Holstein cows. Five cows, around 88±28 days in milk, were distributed in a 5 × 5 Latin square design and fed diets containing different levels of DBG (0, 25, 50, 75, and 100%). The forage:concentrate ratio of the diet was 50:50. Feed intake, dry matter, nutrient digestibility, microbial synthesis, milk production and composition, and the economic viability of the diets were evaluated. There was reduction in dry matter intake and, consequently, in crude protein and non-fiber carbohydrates with increased levels of DBG. This occurred due to physical limitation of rumen caused by increased neutral detergent fiber intake. Ether extract intake also increased with levels of DBG due to higher concentrations of this nutrient in the diet. Apparent dry matter, organic matter, ether extract, and neutral detergent fiber digestibility increased with replacement of soybean meal by DBG. Milk production showed a quadratic effect and the levels of fat, protein, and total solids reduced linearly. Each 1% of soybean meal replaced by DBG in concentrate led to a reduction of 0.04, 0.02, and 0.06 g kg^-1 of milk fat, protein, and total solids, respectively. The milk production efficiency increased linearly and the microbial synthesis efficiency was not affected. The economic return increased along with the DBG levels. Thus, DBG levels replacing up to 75% of soybean meal can be used to feed lactating cows, since it provides improvements in digestibility, milk production efficiency, and economic return without affecting microbial efficiency.