RESUMO

The objective of this study was to evaluate the effects of corn hybrid and processing methods on intake and digestibility of nutrients, rumen fermentation and blood metabolites of steers fed no-forage finishing diets. Four ruminally fistulated Nellore castrated steers (502 ± 15 kg initial body weight) were distributed in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement consisting of two corn hybrids (semi-dent and flint) and two processing methods (dry milled and high moisture grain). Interactions of hybrid and processing methods were observed on intake of dry matter (DM), organic matter (OM) and crude protein (CP), as well as on digestibility of DM and CP, rumen pH and ammonia nitrogen (N-NH3 ). There was no interaction between hybrid and processing for the volatile fatty acids (VFA) total, acetate (C2), propionate (C3), isobutyric (iC4) and valeric (nC5) concentrations. VFA total concentration shown an average of 103.4 mmol/L. The C2 and C3 concentrations had no effect of the hybrid or processing with averages of 58.7 mmol/L for C2, and 31.3 mmol/l for C3. There was an effect of the processing method on starch consumption and fecal pH, the highest values were observed in grains with high moisture content. Starch digestibility was 0.89 g/g in dry milled and 0.96 g/g in high moisture corn. The greatest digestibility of starch in high moisture corn, irrespective of the corn hybrid, provided evidence of an increase in the energy supply, which may improve the feed efficiency and growth performance of cattle fed no-roughage finishing diets.

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ABSTRACT: This study aimed to evaluate the quality traits and fatty acid profile of beef from Nellore and Angus bulls fed whole shelled corn (WSC) and ground corn plus maize silage (GC) diets. Eighteen Nellore and 18 Angus young bulls [381 ± 12 kg initial body weight (BW) and an average age of 20 ± 1.9 months] were used in a completely randomized design using a 2 × 2 factorial arrangement and were slaughtered at a final BW of 451.5 kg and 545.5 kg, respectively. Twentyfour hours after slaughter, samples of longissimus thoracis muscle were collected for the analysis of lipid oxidation, color, fatty acid profile, shear force, and cooking loss. There was no effect of diet × breed interaction on meat color, lipid oxidation, shear force, and cooking loss. Angus beef had lower shear force (p 0.05) than Nellore beef and had a greater concentration of linoleic acid and polyunsaturated fatty acids (PUFA) (p 0.01). Beef of bulls fed WSC tended to have greater concentration of CLA C18:2c9t11 (p = 0.09), greater concentration of CLA C18:2t10c12 (p = 0.01), and PUFA (p = 0.05), and consequently, higher oxidation levels. Angus bulls produced beef with greater tenderness and PUFA concentration. The results of fatty acid show a possible change in biohydrogenation when animals are fed the WSC diet, reducing lipogenesis, as this diet increases the C18:2t10c12 content.

RESUMO

This study aimed to evaluate the quality traits and fatty acid profile of beef from Nellore and Angus bulls fed whole shelled corn (WSC) and ground corn plus maize silage (GC) diets. Eighteen Nellore and 18 Angus young bulls [381 ± 12 kg initial body weight (BW) and an average age of 20 ± 1.9 months] were used in a completely randomized design using a 2 × 2 factorial arrangement and were slaughtered at a final BW of 451.5 kg and 545.5 kg, respectively. Twenty–four hours after slaughter, samples of longissimus thoracis muscle were collected for the analysis of lipid oxidation, color, fatty acid profile, shear force, and cooking loss. There was no effect of diet × breed interaction on meat color, lipid oxidation, shear force, and cooking loss. Angus beef had lower shear force (p < 0.05) than Nellore beef and had a greater concentration of linoleic acid and polyunsaturated fatty acids (PUFA) (p < 0.01). Beef of bulls fed WSC tended to have greater concentration of CLA C18:2c9t11 (p = 0.09), greater concentration of CLA C18:2t10c12 (p = 0.01), and PUFA (p = 0.05), and consequently, higher oxidation levels. Angus bulls produced beef with greater tenderness and PUFA concentration. The results of fatty acid show a possible change in biohydrogenation when animals are fed the WSC diet, reducing lipogenesis, as this diet increases the C18:2t10c12 content.

Assuntos

RESUMO

This study aimed to evaluate the quality traits and fatty acid profile of beef from Nellore and Angus bulls fed whole shelled corn (WSC) and ground corn plus maize silage (GC) diets. Eighteen Nellore and 18 Angus young bulls [381 ± 12 kg initial body weight (BW) and an average age of 20 ± 1.9 months] were used in a completely randomized design using a 2 × 2 factorial arrangement and were slaughtered at a final BW of 451.5 kg and 545.5 kg, respectively. Twenty­four hours after slaughter, samples of longissimus thoracis muscle were collected for the analysis of lipid oxidation, color, fatty acid profile, shear force, and cooking loss. There was no effect of diet × breed interaction on meat color, lipid oxidation, shear force, and cooking loss. Angus beef had lower shear force (p < 0.05) than Nellore beef and had a greater concentration of linoleic acid and polyunsaturated fatty acids (PUFA) (p < 0.01). Beef of bulls fed WSC tended to have greater concentration of CLA C18:2c9t11 (p = 0.09), greater concentration of CLA C18:2t10c12 (p = 0.01), and PUFA (p = 0.05), and consequently, higher oxidation levels. Angus bulls produced beef with greater tenderness and PUFA concentration. The results of fatty acid show a possible change in biohydrogenation when animals are fed the WSC diet, reducing lipogenesis, as this diet increases the C18:2t10c12 content.

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The present study aimed to evaluate non-fiber carbohydrates (NFC) in sugarcane-based diets on rumen pH, and forage digestibility, and to describe NFC degradation curves. The study consisted of two trials. For the first trial, three rumen cannulated steers, BW of 350 ± 15 kg (mean ± SE), were assigned in a 3×3 Latin Square (LS) design. They were fed diets containing finely-ground (0.9 mm average particle size) corn (GC), steam-rolled corn (SRC), or pelleted citrus pulp (PCP). Each period had 14 d, with the first 12 for adaptation. The 13th d was for serial measurement of rumen pH, and the14th for rumen fluid collection and in vitro incubation for DM and NDF digestibility (IVDMD and IVNDFD) of bermudagrass hay (Hay), corn (CS), and sugarcane (SS) silages. In the second trial, rumen fluid of a cannulated bull, fed corn silage and a regular concentrate, was collected for in vitro digestion of NFC for multiple time points. The incubation results were used to adjust the NFC degradation curves, and calculate lag-time, feed fractions, and degradation rate. Data from first trial was analyzed in a 3×3 LS. The model for the digestibility parameters included fixed effects of forage (Feed), diets with NFC (Diet), and their interaction (Feed × Diet), and random effect of animal and period. The model for rumen pH included fixed effect of diet, time as repeated measures, animal and period as random effects. The significance was considered at probability ≤ 5% (α = 0.05). The NFC degradation curves were adjusted using the PROC NLIN procedure from SAS, and equation parameters compared using confidence intervals. There was a Diet × Time interaction on rumen pH (P = 0.04), where SRC decreased pH compared to PCP and GC diets at the time 6 h, only. There was no Feed × Diet interaction effect (P > 0.05) for any digestibility parameter. There was a Feed effect on both IVDMD and IVNDFD, either after 30 or 48 h incubation (P < 0.01). The CS had the greatest IVDMD, followed by SS and Hay, after 30 and 48 h of incubation. The CS had the greatest IVNDFD after 30 h, compared to SS and Hay. However, for IVNDFD after 48 h, CS presented the greatest mean, followed by SS and Hay. The rumen fluid from animals fed SRC decreased both IVDMD and IVNDFD (P < 0.05) of all roughages after 48 h. Results from the second trial showed that the PCP had lower Lag Time, B fraction and greater kd compared to both corn sources, and SRC had greater kd than GC. In conclusion, the SRC diet decreased rumen pH 6 h after feeding and, consequently, decreased fiber digestibility of the tropical forage sources evaluated. Although the PCP had lower lag time, and faster rate of degradation of B fraction, it did not negatively affect rumen pH or fiber digestibility of forage.(AU)

O presente estudo teve como objetivo avaliar os carboidratos não-fibrosos (CNF) em dietas à base de cana-de-açúcar sobre o pH ruminal e digestibilidade da forragem, e descrever as curvas de degradação dos CNF. O estudo foi composto de dois ensaios. No primeiro, três novilhos canulados no rúmen, com peso vivo de 350 ± 15 kg (Média ± DP), foram alocados em um quadrado latino (QL) 3×3, e alimentados com dietas contendo: milho moído (MM, tamanho de partículas 0,9 mm), laminado a vapor (MLV) ou polpa cítrica peletizada (PCP). Cada período tinha 14 d, sendo os primeiros 12 para adaptação e o 13º para a medição seriada do pH e o 14º para a coleta de líquido ruminal e incubação in vitro para digestibilidade da MS e FDN (DIVMS e DIVFDN) de feno de bermudagrass (Feno) e silagens de milho (SM) e cana (SC). No segundo ensaio, coletou-se fluido ruminal de um touro canulado, alimentado com silagem de milho e concentrado padrão, para digestão in vitro dos CNF em vários tempos. Esses resultados foram utilizados para ajustar as curvas de degradação dos CNF e calcular o tempo de colonização, frações alimentares e taxa de degradação. Os resultados do primeiro ensaio foram analisados em um QL 3×3. O modelo dos parâmetros de digestibilidade incluiu efeito fixo de forragem (Alimento), dieta com CNF (Dieta) e interação (Alimento × Dieta), e efeito aleatório de animal e período. O modelo para pH incluiu efeito fixo de Dieta, Tempo como medida repetida, animal e período como aleatórios. Foi considerada a probabilidade significativa de ≤ 5% (α = 0,05). As curvas de degradação dos CNF foram ajustadas pelo PROC NLIN do SAS, e parâmetros de equação comparados por intervalo de confiança. Houve interação Dieta × Tempo no pH ruminal (P = 0,04), onde o MLV diminuiu o pH comparado com PCP e MM apenas no tempo 6 h. Não houve interação Alimento × Dieta (P > 0,05) para nenhum parâmetro de digestibilidade. Houve efeito de Alimento sobre a DIVMS e DIVFDN, após 30 e 48 h de incubação (P < 0,01). A SM teve a maior DIVMS, seguido por SC e Feno, após 30 e 48 h de incubação. A SM teve a maior DIVFDN após 30 h, comparado com SC e Feno. No entanto, para DIVFDN após 48 h, a SM teve maior média, seguida da SC e Feno. O fluido ruminal de animais alimentados com MLV diminuiu a DIVMS e DIVFDN (P < 0.05) de todas as forragens, após 48 h. Resultados do segundo ensaio mostram que PCP diminuiu o tempo de colonização, fração B e aumentou a kd comparado com os dois milhos, e MLV apresentou maior kd que o MM. Em conclusão, a dieta com MLV diminuiu o pH ruminal no tempo 6 h e, consequentemente, diminuiu a DIVFDN das forragens avaliadas. Embora PCP tenha apresentado menor tempo de colonização e maior taxa de degradação da fração B, não afetou negativamente o pH do rúmen nem a digestibilidade da fibra das forragens. (au)

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RESUMO

The present study aimed to evaluate non-fiber carbohydrates (NFC) in sugarcane-based diets on rumen pH, and forage digestibility, and to describe NFC degradation curves. The study consisted of two trials. For the first trial, three rumen cannulated steers, BW of 350 ± 15 kg (mean ± SE), were assigned in a 3×3 Latin Square (LS) design. They were fed diets containing finely-ground (0.9 mm average particle size) corn (GC), steam-rolled corn (SRC), or pelleted citrus pulp (PCP). Each period had 14 d, with the first 12 for adaptation. The 13th d was for serial measurement of rumen pH, and the14th for rumen fluid collection and in vitro incubation for DM and NDF digestibility (IVDMD and IVNDFD) of bermudagrass hay (Hay), corn (CS), and sugarcane (SS) silages. In the second trial, rumen fluid of a cannulated bull, fed corn silage and a regular concentrate, was collected for in vitro digestion of NFC for multiple time points. The incubation results were used to adjust the NFC degradation curves, and calculate lag-time, feed fractions, and degradation rate. Data from first trial was analyzed in a 3×3 LS. The model for the digestibility parameters included fixed effects of forage (Feed), diets with NFC (Diet), and their interaction (Feed × Diet), and random effect of animal and period. The model for rumen pH included fixed effect of diet, time as repeated measures, animal and period as random effects. The significance was considered at probability ≤ 5% (α = 0.05). The NFC degradation curves were adjusted using the PROC NLIN procedure from SAS, and equation parameters compared using confidence intervals. There was a Diet × Time interaction on rumen pH (P = 0.04), where SRC decreased pH compared to PCP and GC diets at the time 6 h, only. There was no Feed × Diet interaction effect (P > 0.05) for any digestibility parameter. There was a Feed effect on both IVDMD and IVNDFD, either after 30 or 48 h incubation (P < 0.01). The CS had the greatest IVDMD, followed by SS and Hay, after 30 and 48 h of incubation. The CS had the greatest IVNDFD after 30 h, compared to SS and Hay. However, for IVNDFD after 48 h, CS presented the greatest mean, followed by SS and Hay. The rumen fluid from animals fed SRC decreased both IVDMD and IVNDFD (P < 0.05) of all roughages after 48 h. Results from the second trial showed that the PCP had lower Lag Time, B fraction and greater kd compared to both corn sources, and SRC had greater kd than GC. In conclusion, the SRC diet decreased rumen pH 6 h after feeding and, consequently, decreased fiber digestibility of the tropical forage sources evaluated. Although the PCP had lower lag time, and faster rate of degradation of B fraction, it did not negatively affect rumen pH or fiber digestibility of forage.(AU)

O presente estudo teve como objetivo avaliar os carboidratos não-fibrosos (CNF) em dietas à base de cana-de-açúcar sobre o pH ruminal e digestibilidade da forragem, e descrever as curvas de degradação dos CNF. O estudo foi composto de dois ensaios. No primeiro, três novilhos canulados no rúmen, com peso vivo de 350 ± 15 kg (Média ± DP), foram alocados em um quadrado latino (QL) 3×3, e alimentados com dietas contendo: milho moído (MM, tamanho de partículas 0,9 mm), laminado a vapor (MLV) ou polpa cítrica peletizada (PCP). Cada período tinha 14 d, sendo os primeiros 12 para adaptação e o 13º para a medição seriada do pH e o 14º para a coleta de líquido ruminal e incubação in vitro para digestibilidade da MS e FDN (DIVMS e DIVFDN) de feno de bermudagrass (Feno) e silagens de milho (SM) e cana (SC). No segundo ensaio, coletou-se fluido ruminal de um touro canulado, alimentado com silagem de milho e concentrado padrão, para digestão in vitro dos CNF em vários tempos. Esses resultados foram utilizados para ajustar as curvas de degradação dos CNF e calcular o tempo de colonização, frações alimentares e taxa de degradação. Os resultados do primeiro ensaio foram analisados em um QL 3×3. O modelo dos parâmetros de digestibilidade incluiu efeito fixo de forragem (Alimento), dieta com CNF (Dieta) e interação (Alimento × Dieta), e efeito aleatório de animal e período. O modelo para pH incluiu efeito fixo de Dieta, Tempo como medida repetida, animal e período como aleatórios. Foi considerada a probabilidade significativa de ≤ 5% (α = 0,05). As curvas de degradação dos CNF foram ajustadas pelo PROC NLIN do SAS, e parâmetros de equação comparados por intervalo de confiança. Houve interação Dieta × Tempo no pH ruminal (P = 0,04), onde o MLV diminuiu o pH comparado com PCP e MM apenas no tempo 6 h. Não houve interação Alimento × Dieta (P > 0,05) para nenhum parâmetro de digestibilidade. Houve efeito de Alimento sobre a DIVMS e DIVFDN, após 30 e 48 h de incubação (P < 0,01). A SM teve a maior DIVMS, seguido por SC e Feno, após 30 e 48 h de incubação. A SM teve a maior DIVFDN após 30 h, comparado com SC e Feno. No entanto, para DIVFDN após 48 h, a SM teve maior média, seguida da SC e Feno. O fluido ruminal de animais alimentados com MLV diminuiu a DIVMS e DIVFDN (P < 0.05) de todas as forragens, após 48 h. Resultados do segundo ensaio mostram que PCP diminuiu o tempo de colonização, fração B e aumentou a kd comparado com os dois milhos, e MLV apresentou maior kd que o MM. Em conclusão, a dieta com MLV diminuiu o pH ruminal no tempo 6 h e, consequentemente, diminuiu a DIVFDN das forragens avaliadas. Embora PCP tenha apresentado menor tempo de colonização e maior taxa de degradação da fração B, não afetou negativamente o pH do rúmen nem a digestibilidade da fibra das forragens. (au)

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This study was carried out to evaluate the effects of chopped hay levels in high-concentrate diets with whole corn grain (WCG) on performance and carcass traits of finishing Nellore cattle. One hundred and eight 24-month-old Nellore intact males (453 ± 75 kg) were fed one of three WCG-based diets that differed in roughage level: without roughage (WCG), with 5% chopped hay included (WCG5), or with 12% chopped hay included (WCG12) in a block design (based on initial body weight) for 86 days. Animals fed WCG5 or WCG12 had significantly improved on final body weight, dry matter intake, average daily gain, feed efficiency, hot carcass weight, and dressing percentage when compared to those fed WCG. The Longissimus muscle area (P = 0.1108), backfat thickness (BFT; P = 0.6089), and rump fat thickness (P = 0.1798) were not affected by roughage levels. Therefore, using WCG diets without roughage negatively affects the performance of feedlot Nellore cattle but does not affect carcass traits and does lead to the minimum BFT required by the industry.

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The objective of our study was to investigate the associative effects of feeding Ca salts of palm fatty acids (FA) and corn grain-processing method on production, nutrient digestibility, energy balance, and carryover effects of early-lactation dairy cows grazing a tropical pasture. Treatment diets were offered from 3 to 16 wk postpartum (treatment period), in which all cows grazed elephant grass (Pennisetum purpureum L. Cameroon) and treatments were added to a concentrate supplement. Treatments were flint corn grain-processing method either as fine ground (FGC) or steam-flaked (SFC) associated with Ca salts of palm FA supplementation either not supplemented or supplemented (CSPO). From 17 to 40 wk postpartum (carryover period) all cows received a common diet fed as total mixed ration. During the treatment period, a tendency for an interaction between CSPO and corn grain-processing method were observed for milk yield, milk fat yield, and energy-corrected milk (ECM), as CSPO caused them to increased to a greater extent in the FGC diet compared with the SFC diet. Furthermore, a tendency for an interaction between CSPO and corn grain-processing method was observed for body weight change, because CSPO increased body weight loss in the FGC diet but not in the SFC diet. The CSPO increased milk yield, milk fat yield, 3.5% fat-corrected milk, ECM, and cumulative milk yield compared with not supplemented. Also, CSPO increased energy intake, milk energy output, and energy partitioning toward milk, whereas reduced energy was allocated to body reserves. The SFC increased milk yield, ECM, milk protein yield, milk casein yield, and cumulative milk yield, and decreased milk urea N compared with FGC. The SFC compared with FGC also increased body condition score and body weight change, and increased energy partitioning toward body reserves. During the carryover period, an interaction between CSPO and corn grain-processing method was observed for milk yield, which occurred because CSPO maintained higher milk yield in the FGC diet but not in the SFC diet. Therefore, in the carryover period, the additive effect between SFC and CSPO that occurred in the treatment period was not maintained throughout the carryover period. However, CSPO increased yields of milk fat, protein, casein as well as fat-corrected milk and ECM. In conclusion, corn grain-processing method interacts with CSPO supplementation on production responses and carryover effects of grazing cows. When CSPO was fed in the FGC diet, milk production increased to a greater extent than when fed in the SFC diet, but also caused greater mobilization of reserves at early lactation. This suggests an interaction between fat supplementation and corn grain-processing method on energy partitioning of dairy cows. Also, both supplementation with CSPO and SFC were effective strategies to increase energy intake and yields of milk and milk solids. The carryover effect on milk production was greater for CSPO supplementation than corn grain-processing method, whereas feeding SFC diets had lower mobilization of reserves and less body weight and body condition score variation throughout lactation.

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