Nitrogen metabolism in lactating goats fed with diets containing different protein sources.

This study aimed to evaluate urea excretion, nitrogen balance and microbial protein synthesis in lactating goats fed with diets containing different protein sources in the concentrate (soybean meal, cottonseed meal, aerial part of cassava hay and leucaena hay). Four Alpine goats whose mean body weight was 42.6±6.1 kg at the beginning of the experiment, a mean lactation period of 94.0±9.0 days and a production of 1.7±0.4 kg of milk were distributed in a 4×4 Latin square with four periods of 15 days. Diets were formulated to be isonitrogenous, containing 103.0 g/kg of CP, 400 g/kg of Tifton 85 hay and 600 g/kg of concentrate. Diet containing cottonseed meal provided (p<0.05) increased excretion of urea and urea nitrogen in the urine (g/d and mg/kg of BW) when compared with leucaena hay. The diets affected the concentrations of urea nitrogen in plasma (p<0.05) and excretion of urea nitrogen in milk, being that soybean meal and cottonseed meal showed (p<0.05) higher than the average aerial part of the cassava hay. The use of diets with cottonseed meal as protein source in the concentrate in feeding of lactating goats provides greater nitrogen excretion in urine and negative nitrogen balance, while the concentrate with leucaena hay as a source of protein, provides greater ruminal microbial protein synthesis.

Effects of increasing inclusion of sodium hydroxide treatment on growth performance, carcass characteristics, and feeding behavior of steers fed 50% DDGS.

Objectives were to determine the dietary inclusion level of NaOH in a dried distillers grains with solubles (DDGS)-based diet needed to improve growth performance and carcass characteristics of feedlot steers, and to determine the effects of NaOH treatment of DDGS on pattern of feed intake. Based on previous research regarding the acidity of DDGS, we hypothesized that using NaOH in cattle fed 50% DDGS-based diets to neutralize the acidity inherent in DDGS would improve growth performance of cattle but shift intake patterns. Angus-cross steers (120 total) were blocked into 2 BW blocks (light, initial BW = 211 ± 27 kg; and heavy, initial BW = 261 ± 27 kg) and allotted randomly within block to 20 pens (6 steers per pen; = 30). Pens within block were assigned randomly to 1 of 4 dietary treatments: 1) 50% DDGS, untreated; 2) 50% DDGS, treated with 0.5% NaOH (DM basis); 3) 50% DDGS, treated with 1.0% NaOH (DM basis); or 4) 50% DDGS, treated with 1.5% NaOH (DM basis). The remainder of the diets contained 20% dry-rolled corn, 20% corn silage, and 10% mineral and vitamin supplement, on a DM basis. Cattle were fed in a GrowSafe system. There were no effects ( ≥ 0.21) of increasing NaOH inclusion on final BW, ADG, or G:F. Increasing NaOH in the diet increased meal duration (linear; = 0.02) and tended to increase meal size (linear; = 0.06), but did not affect overall number of meals per day (linear; = 0.21) or overall DMI ( ≥ 0.40) for the course of the trial. Relative to cattle fed DDGS treated with 0, 0.5 or 1% NaOH (DM basis), steers fed DDGS treated with 1.5% NaOH consumed a larger proportion of their meals in the afternoon. However, regardless of treatment, all steers consumed 78% or more of their feed in the first 12 h post-feeding. There were no effects ( ≥ 0.19) of increasing NaOH inclusion on HCW, LM area, dressing percentage, KPH, back fat thickness, and marbling. There was a linear ( = 0.02) decrease in USDA Yield Grade (YG) 3 and a tendency ( = 0.09) for a quadratic response in carcasses grading USDA YG 4 as NaOH concentration increased in the diets; however, there were no other YG differences. The quality grade response followed marbling score and was not different ( ≥ 0.11) among treatments. Thus, there were no effects of feeding DDGS treated with NaOH on growing cattle performance or carcass characteristics. However, NaOH inclusion shifted the pattern of intake slightly to the afternoon hours, and increased meal duration without increasing the total number of meals per day.

Effects of sodium hydroxide treatment of dried distillers' grains on digestibility, ruminal metabolism, and metabolic acidosis of feedlot steers.

The objectives were to determine the optimum inclusion of NaOH necessary to buffer the acidity of dried distillers' grains with solubles (DDGS) and its effects on digestibility, ruminal metabolism, and metabolic acidosis in feedlot steers. Rumen cannulated Angus-crossed steers were blocked by BW (small: 555 ± 42 kg initial BW, = 4; large: 703 ± 85 kg initial BW, = 4) over four 21-d periods in a replicated 4 × 4 Latin square design. Steers were assigned to 1 of 4 dietary treatments: 1) 50% untreated DDGS, 2) 50% DDGS treated with 0.5% (DM basis) sodium hydroxide (NaOH), 3) 50% DDGS treated with 1.0% (DM basis) NaOH, and 4) 50% DDGS treated with 1.5% (DM basis) NaOH. The remainder of the diets, on a DM basis, was composed of 20% corn silage, 20% dry-rolled corn, and 10% supplement. Ruminal pH was not affected by treatments ( = 0.56) or by a treatment × time interaction ( = 0.15). In situ NDF and ruminal DM disappearance did not differ ( ≥ 0.49 and ≥ 0.47, respectively) among treatments. Similar to in situ results, apparent total tract DM and NDF digestibility were not affected ( ≥ 0.33 and ≥ 0.21, respectively) by increasing NaOH inclusion in the diets. Urinary pH increased (linear, < 0.01) with increasing NaOH concentration in the diet. Blood pH was not affected ( ≥ 0.20), and blood total CO and partial pressure of CO were similar ( ≥ 0.56 and ≥ 0.17, respectively) as NaOH increased in the diet. Increasing NaOH in the diet did not affect ( ≥ 0.21) ruminal concentrations of total VFA. There were no linear ( = 0.20) or quadratic ( = 0.20) effects of treatment on ruminal acetate concentrations, nor was there a treatment × time interaction ( = 0.22) for acetate. Furthermore, there were no effects ( ≥ 0.90) of NaOH inclusion on ruminal propionate concentration. However, there was a quadratic response ( = 0.01) of ruminal butyrate concentrations as NaOH inclusion increased in the diet; ruminal butyrate concentrations were greatest with the 0.5 and 1.0% NaOH treatments of DDGS. In the current study, feeding DDGS treated with NaOH did not increase fiber digestibility nor was it necessary to alleviate a possible metabolic acidosis. Alkali treatment of DDGS did not increase average ruminal pH or blood pH.

Cinética e parâmetros de fermentação ruminal in vitro de silagens de parte aérea e raízes de mandioca / Kinetic parameters and in vitro rumen fermentation of cassava foliage and roots silages

Foram avaliados os efeitos do emurchecimento e da inclusão de raízes 0, 15, 30 e 45% da matéria natural sobre a cinética e os parâmetros da fermentação ruminal de silagens da parte aérea da mandioca. A produção acumulada de gases (PAG) às 96 horas de incubação foi influenciada significativamente (P<0,05) pela interação emurchecimento versus inclusão de raízes. Para a PAG, houve elevação linear de 1,88mL a cada unidade percentual de raiz adicionada às silagens não emurchecidas e efeito quadrático nas silagens emurchecidas, com produção máxima de 226mL de gases, com a inclusão de 30,5% de raízes. A degradabilidade verdadeira in vitro da MS (DVIMS) das silagens apresentou significância (P<0,05) para o emurchecimento e para a interação inclusão de raízes versus tempo de incubação. O emurchecimento reduziu, aproximadamente, 2% da degradabilidade da silagem, enquanto a inclusão de raízes propiciou elevação linear dessa variável, que atingiu o valor máximo às 24 horas de incubação.

The effects of wilting and roots inclusion (0, 15, 30 and 45% fresh matter) on rumen fermentation kinetics and parameters of cassava foliage silages were evaluated. Total gas production (TGP) after 96 hours of incubation was significantly influenced (P <0.05) by the interaction between wilting and roots inclusion. TGP was linearly increased by 1.88 mL for each percent unit of root added to the wilted silage, whereas, for wilted ones, a quadratic effect was observed, with a maximum gas cumulative output of 226 mL for 30.5% roots addition. The true DM degradability of silages in vitro (IVTDMD) showed significance (P<0.05) to wilting and interaction between root inclusion and incubation time. Wilting reduced silage degradability in approximately 2%, while root inclusion led to linear increases in this variable, which reached its peak at 24h of incubation.

Fracionamento de carboidratos e proteínas de gramíneas tropicais cortadas em três idades / Carbohydrates and proteins fractions of tropical grasses cut at three ages

Avaliou-se o fracionamento dos carboidratos e das proteínas das gramíneas tropicais tifton 85 (Cynodon dactylon cv Tiffon 85), braquiária (Brachiaria brizantha cv Marandu) e tanzânia (Panicum maximum Jacq. cv Tanzânia), cortadas aos 28, 35 e 54 dias de idade. Determinaram-se os teores de matéria seca (MS), matéria orgânica (MO), proteína bruta (PB), extrato etéreo (EE), fibra em detergente neutro corrigida para cinzas e proteína (FDN CP), fibra em detergente ácido (FDA), lignina (LIG), nitrogênio insolúvel em detergente neutro (NIDN) e nitrogênio insolúvel em detergente ácido (NIDA). Para PB determinaram-se as frações A, B1+B2, B3 e C, e para os carboidratos as frações A+B1, B2 e C. Foi utilizado o delineamento inteiramente ao acaso, em arranjo em parcelas (gramíneas) subdivididas (idades de corte). Houve efeito significativo (P<0,05) da idade de corte sobre os teores de MS, FDN CP, NIDN e NIDA. Os teores de PB apresentaram declínio com o avanço da idade. O capim-marandu apresentou teores elevados para as frações A+B1 e B2 dos carboidratos (25,5 e 34,8 por cento dos carboidratos totais, respectivamente) e para as frações A e B1+B2 das proteínas (28,1 por cento aos 35 dias e 53,8 por cento da PB aos 28 dias, respectivamente).

The carbohydrates and proteins fractions of tropical grasses Tifton 85 (Cynodon dactylon cv Tifton 85), brachiaria (Brachiaria brizantha cv Marandu), and Tanzania (Panicum maximum Jacq. cv Tanzania) were evaluated at cut ages of 28, 35, and 54 days. Contents of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), fiber in neutral detergent corrected for ashes and protein (NDF CP), fiber in acid detergent (ADF), lignin (LIG), neutral detergent insoluble nitrogen (NDIN), and acid detergent insoluble nitrogen (ADIN) were determined. For CP, the A, B1+B2, B3, and C fractions were determined. For carbohydrates, the fractions A+B1, B2, and C were measured. A completely randomized split-plot design was used. Effect of cut age on DM, NDF CP, NDIN and ADIN was observed. The CP contents decreased with the progress of the age for the three grasses. The Marandu grass presented high percentage of the fractions A+B1 and B2 for the total carbohydrate (25.5 and 34.8 percent, respectively) and of the fractions A and B1+B2 for the proteins (28.1 percent CP at 35 days and 53.8 percent CP at 28 days, respectively).