Effect of pregnancy and feeding level on voluntary intake, digestion, and microbial nitrogen synthesis in Zebu beef cows.

The objective of this research was to evaluate how pregnancy and feeding regimens affect the feed intake, digestibility, and efficiency of microbial nitrogen (N) synthesis in beef cows. Forty-four multiparous Nellore cows, comprising 32 gestating and 12 non-gestating cows, with an average weight of 451 ± 10 kg, were assigned to either a HIGH (ad libitum) or LOW (limited feeding at 1.2 times maintenance based on the NRC) feeding regimen during the gestational period. The dry matter intake (DMI) in kg/d was significantly greater (P < 0.01) in HIGH-fed cows. The DMI reduced (P < 0.05) in proportion to the shrunk body weight (SBW) as days of pregnancy (DOP) increased. The interaction between feeding level and DOP was significant (P < 0.05) for the digestibility of dry matter (DM), organic matter (OM), N compounds, ether extract (EE), ash- and protein-free neutral detergent fiber (NDFap), gross energy (GE), and total digestible nutrients (TDN). Except for DM and TDN digestibility, there was a reduced nutrient digestibility as gestation progressed in HIGH-fed cows. In contrast, digestibility increased as a function of DOP in LOW-fed cows. Microbial N synthesis (g/day) was significantly higher in HIGH-fed cows (P < 0.001) compared to LOW-fed cows. The efficiency of microbial N production per g of N intake and kg of digestible OM intake was (P = 0.021) and tended (P = 0.051) to be greater in LOW-fed cows compared to HIGH-fed cows. In summary, HIGH-fed Nellore cows reduce feed intake and digestibility with advancing gestation, affecting feed utilization. In addition, LOW-fed cows, showed higher microbial protein synthesis efficiency, potentially making them more nutrient-efficient under challenging nutritional conditions.

Effects of parity order on performance, metabolic, and hormonal parameters of grazing beef cows during pre-calving and lactation periods.

BACKGROUND: Metabolic profile evaluation is a tool widely used in ruminant nutrition as metabolic cues that relate nutrition to physiology. Metabolic and hormonal traits change during pre-partum and lactation according to parity in dairy cows, but studies of beef cows under grazing are scarce. The present study aimed to evaluate how metabolic and hormonal traits change over time, their relationship to performance, and determine if these factors differ according to the parity order of grazing beef cows. Thirty-six pregnant Nellore cows (12 nulliparous, 12 primiparous, and 12 multiparous) were used. The study started at 60 d prepartum until 203 d of lactation. RESULTS: The initial body weight (BW) and final BW were higher for multiparous cows (P > 0.05). An interaction occurred between parity and day (P < .0001) for body condition score. Nulliparous and primiparous body condition score were reduced from - 60 prepartum to 30 postpartum, then stabilized 60 postpartum (P < 0.05), while multiparous maintained body condition score from - 60 days until 60 days postpartum (P > 0.05). Calf BW, final BW, and average daily gain did not differ between parities (P > 0.05). Effect of day (P < 0.05) was detected for non-esterified fatty acids, triglycerides, total cholesterol, LDL, VLDL, progesterone, and insulin. An interaction was observed between parity and days for glucose, HDL, ß-hydroxybutyrate, creatinine and IGF-1 (P < 0.05). Parity affected serum urea nitrogen, total proteins, albumin, and globulins (P < 0.05). Parity and day relative to calving did not impact total T3 and T4 (P > 0.05). CONCLUSIONS: Hormonal and metabolic profile is strongly influenced by the stage of lactation. Time effects (pre-partum and lactation period) were more pronounced in nulliparous since they displayed more unbalanced metabolic and hormonal traits and lowered BCS pre- and postpartum.

Performance, metabolic and hormonal responses of grazing Nellore cows to an energy-protein supplementation during the pre-partum phase.

BACKGROUND: Supplementation programs for prepartum beef cows are usually adopted because the nutritional status of the cows upon calving is a main factor impacting reproductive performance of the next production cycle. This study evaluated the effects of 60-d pre-partum energy-protein supplementation on performance, metabolic and hormonal responses during the peripartum phase of grazing beef cows. Thirty-eight pregnant multiparous Nellore cows were assigned to a completely randomized design with two treatments: control (no supplement) and supplementation (1.5 kg of energy-protein per d with 30% crude protein, dry matter basis). RESULTS: The supplemented cows had higher ADG pre-partum (P < 0.10), but postpartum ADG did not differ between treatments. Supplementation did not affect BCS and calf BW upon calving, on days 45 and 90, milk yield and composition (P > 0.10). No differences were found for forage intake and neutral detergent fiber digestibility (P > 0.10). The intake and digestibility of CP and OM increased in response to supplementation (P < 0.10). An interaction occurred between supplementation and peripartum days for BUN, ßHB, T3 and T4, which had higher concentrations for supplemented cows at pre-partum period (P < 0.10). Concentration of others blood parameters significantly changed along peripartum days (P < 0.10). There was no difference in pregnancy rates and days from calving to conception between treatments (P > 0.10). CONCLUSIONS: Providing an energy and protein supplement to grazing Nellore cows over the last 60 d of gestation improved their pre-partum energy balance. However, no post-partum carryover effects were detected.

Intake, digestibility, and rumen and metabolic characteristics of cattle fed low-quality tropical forage and supplemented with nitrogen and different levels of starch.

OBJECTIVE: Effects of nitrogen supplementation associated with different levels of starch on voluntary intake, digestibility, and rumen and metabolic characteristics of cattle fed low-quality tropical forage (Brachiaria decumbens hay, 7.4% crude protein, CP) were evaluated using ruminal and abomasal cannulated steers. METHODS: Five European×Zebu young bulls (186 kg body weight, BW) were distributed according to a 5×5 Latin square. The following treatments were evaluated: control, supplementation with 300 g CP/d (0:1), supplementation with 300 g starch/d and 300 g CP/d (1:1), supplementation with 600 g starch/d and 300 g CP/d (2:1), and supplementation with 900 g starch/d and 300 g CP/d (3:1). A mixture of nitrogenous compounds provided 1/3 from true protein (casein) and 2/3 from non-protein nitrogen (mixture of urea and ammonium sulphate, 9:1) was used as the nitrogen supplement. In order to supply energy a unique source of corn starch was used. RESULTS: Supplements increased (p<0.05) dry matter intake, but did not affect (p>0.05) forage intake. There was a cubic effect (p<0.05) of starch on voluntary intake. This was attributed to the highest forage intake (g/kg BW) when using the 2:1 starch:CP ratio. Supplements increased (p<0.05) organic matter (OM) digestibility, but did not affect (p>0.05) neutral detergent fibre corrected for ash and protein (NDFap) digestibility. There was a positive linear effect (p<0.05) of the amount of starch supplemented on OM digestibility. Total NDFap digestibility was not affected (p>0.05) by the amount of supplemental starch. Ruminal ammonia nitrogen concentrations were higher (p<0.05) in supplemented animals, however, a negative linear effect (p<0.05) of amount of starch was observed. Supplements increased (p<0.05) the nitrogen balance (NB) and efficiency of nitrogen utilization. These effects were attributed to increased body anabolism, supported by higher (p<0.05) serum concentration of insulin-like growth factor 1. Increasing the amount of starch tended (p<0.06) to linearly increase the NB. In spite of this, there was a highest NB value for the 2:1 starch:CP ratio amongst the treatments with supplementation. CONCLUSION: Nitrogen supplementation in cattle fed low-quality tropical forage increases nitrogen retention in the animal's body. An additional supply of starch increases nitrogen retention by increasing energy availability for both rumen and animal metabolism.

Does supplementation of beef calves by creep feeding systems influence milk production and body condition of the dams?

The aim of this study was to evaluate the effects of beef calves' supplementation in creep feeding systems on milk yield, body weight (BW), and body condition score (BCS) of their dams on tropical pastures using a meta-analytical approach. The database was obtained from 11 experiments conducted between 2009 and 2014 in Brazil, totaling 485 observations (cows). The database consisted of 273 Nellore and 212 crossbred (7/8 Nellore × 1/8 Holstein) cows. All experiments were carried out in the suckling phase (from 3 to 8 months of age of calves) during the transition phase between rainy and dry seasons from February to June of different years. The data were analyzed by a meta-analytical approach using mixed models and taking into account random variation among experiments. Calves' supplementation (P ≥ 0.59) and the calves' sex (P ≥ 0.48) did not affect milk yield of cows. The average fat-corrected milk (FCM) yield was 6.71 and 6.83 kg/day for cows that had their calves supplemented and not supplemented, respectively. Differences were observed (P < 0.0001) for milk yield due to the genetic group where crossbred cows presented greater FCM yield (7.37 kg/day) compared with Nellore cows (6.17 kg/day). There was no effect of the calves' supplementation on BW change (P ≥ 0.11) and BCS change (P ≥ 0.23) of the cows. Therefore, it is concluded that supplementation of beef calves using creep feeding systems in tropical pastures does not affect milk yield, body weight, or body condition of their dams.

Nutritional Performance of Cattle Grazing during Rainy Season with Nitrogen and Starch Supplementation.

The objective of this work was to evaluate the effects of supplementation with nitrogen and starch on the nutritional performance of grazing cattle during the rainy season. Five rumen cannulated Nellore steers, averaging 211 kg of body weight (BW), were used. Animals grazed on five signal grass paddocks. Five treatments were evaluated: control (forage only), ruminal supplementation with nitrogen at 1 g of crude protein (CP)/kg BW, ruminal supplementation with starch at 2.5 g/kg BW, supplementation with nitrogen (1 g CP/kg BW) and starch (2.5 g/kg BW), and supplementation with nitrogen (1 g CP/kg BW) and a mixture of corn starch and nitrogenous compounds (2.5 g/kg BW), thereby resulting in an energy part of the supplement with 150 g CP/kg of dry matter (DM). This last treatment was considered an additional treatment. The experiment was carried out according to a 5 ×5 Latin square design following a 2×2+1 factorial arrangement (with or without nitrogen, with or without starch, and the additional treatment). Nitrogen supplementation did not affect (p>0.10) forage intake. Starch supplementation increased (p<0.10) total intake but did not affect (p<0.10) forage intake. There was an interaction between nitrogen and starch (p<0.10) for organic matter digestibility. Organic matter digestibility was increased only by supplying starch and nitrogen together. Nitrogen balance (NB) was increased (p<0.10) by the nitrogen supplementation as well as by starch supplementation. Despite this, even though a significant interaction was not observed (p>0.10), NB obtained with nitrogen plus starch supplementation was greater than NB obtained with either nitrogen or starch exclusive supplementation. Supplementation with starch and nitrogen to beef cattle grazing during the rainy season can possibly improve digestion and nitrogen retention in the animal..

Estudo colaborativo para avaliação dos teores de proteína bruta em alimentos utilizando o método de Kjeldhal

SUMMARY A collaborative study was conducted to evaluate the crude protein (CP) content in feeds in seven feed analysis laboratories from institutions linked to the National Institute of Science and Technology in Animal Science (INCT-CA). Were evaluated four samples of different feeds (sugarcane, corn silage, soybean meal and corn grain) and four nitrogen compounds assumed as standards (urea, monobasic ammonium phosphate, ethylene diamine tetraacetic acid and ammonium sulfate) to measure the accuracy of the estimates. Each laboratory analyzed the samples for six days, consecutive or not, with three replicates per sample per day of evaluation. The variances among laboratories and within of laboratories (repeatability) represented 34.5 and 10.3% of the total variation, respectively. The evaluation of nitrogen recovered from the standards showed that 25% of observations presented a significant bias (P 0.001). The overall assessment of the samples demonstrated significant variations (P 0.001) in function of the day of analysis, interaction of material with laboratory, and among laboratories. Additionally, it was found that the variation among laboratories corresponded of 43.6 to 68.2% of the total of random variation, while the repeatability (intra-laboratory variation) represented of 11.9 to 42.8% of reproducibility. The CP contents estimated are dependent of the interaction effect of the evaluated material and laboratory, which reflect the differences between the procedures utilized by each laboratory.

RESUMO Estudo colaborativo foi conduzido para avaliação do teor de proteína bruta (PB) em diferentes amostras de alimentos em sete diferentes laboratórios de análise de alimentos de instituições integrantes do Instituto Nacional de Ciência e Tecnologia de Ciência Animal (INCTCA). Foram utilizadas amostras de quatro alimentos (cana-de-açúcar, silagem de milho, farelo de soja e milho grão) e quatro compostos que foram assumidos como padrões para aferição da exatidão das estimativas (ureia, fosfato de amônia monobásico, ácido etileno diamínico tetra-acético e sulfato de amônio). Cada laboratório analisou as amostras durante seis dias, consecutivos ou não, sendo realizadas três repetições por amostra em cada dia de avaliação. As variâncias entre laboratórios e dentro de laboratórios (repetibilidade) representaram 34,5 e 10,3 % da variação total. A avaliação das recuperações de nitrogênio a partir dos padrões permitiu evidenciar que 25% das observações apresentaram vícios significativos de recuperação (P 0,001). A avaliação global das amostras propiciou variações significativas (P 0,001) em função: do dia de análise, interação do material com o laboratório e entre laboratórios. Adicionalmente, verificou-se que a variação dos resultados entre laboratórios correspondeu de 43,6 a 68,2% da variação aleatória total, ao passo que a repetibilidade (variação intra-laboratorial) representou de 11,9 a 42,8% da reprodutibilidade. Os teores de PB estimados pelos laboratórios participantes são dependentes do efeito de interação do material avaliado e do laboratório, possível reflexo das várias diferenças entre os procedimentos utilizados por cada laboratório.

Estudo colaborativo para avaliação dos teores de proteína bruta em alimentos utilizando o método de Kjeldhal

SUMMARY A collaborative study was conducted to evaluate the crude protein (CP) content in feeds in seven feed analysis laboratories from institutions linked to the National Institute of Science and Technology in Animal Science (INCT-CA). Were evaluated four samples of different feeds (sugarcane, corn silage, soybean meal and corn grain) and four nitrogen compounds assumed as standards (urea, monobasic ammonium phosphate, ethylene diamine tetraacetic acid and ammonium sulfate) to measure the accuracy of the estimates. Each laboratory analyzed the samples for six days, consecutive or not, with three replicates per sample per day of evaluation. The variances among laboratories and within of laboratories (repeatability) represented 34.5 and 10.3% of the total variation, respectively. The evaluation of nitrogen recovered from the standards showed that 25% of observations presented a significant bias (P 0.001). The overall assessment of the samples demonstrated significant variations (P 0.001) in function of the day of analysis, interaction of material with laboratory, and among laboratories. Additionally, it was found that the variation among laboratories corresponded of 43.6 to 68.2% of the total of random variation, while the repeatability (intra-laboratory variation) represented of 11.9 to 42.8% of reproducibility. The CP contents estimated are dependent of the interaction effect of the evaluated material and laboratory, which reflect the differences between the procedures utilized by each laboratory.

RESUMO Estudo colaborativo foi conduzido para avaliação do teor de proteína bruta (PB) em diferentes amostras de alimentos em sete diferentes laboratórios de análise de alimentos de instituições integrantes do Instituto Nacional de Ciência e Tecnologia de Ciência Animal (INCTCA). Foram utilizadas amostras de quatro alimentos (cana-de-açúcar, silagem de milho, farelo de soja e milho grão) e quatro compostos que foram assumidos como padrões para aferição da exatidão das estimativas (ureia, fosfato de amônia monobásico, ácido etileno diamínico tetra-acético e sulfato de amônio). Cada laboratório analisou as amostras durante seis dias, consecutivos ou não, sendo realizadas três repetições por amostra em cada dia de avaliação. As variâncias entre laboratórios e dentro de laboratórios (repetibilidade) representaram 34,5 e 10,3 % da variação total. A avaliação das recuperações de nitrogênio a partir dos padrões permitiu evidenciar que 25% das observações apresentaram vícios significativos de recuperação (P 0,001). A avaliação global das amostras propiciou variações significativas (P 0,001) em função: do dia de análise, interação do material com o laboratório e entre laboratórios. Adicionalmente, verificou-se que a variação dos resultados entre laboratórios correspondeu de 43,6 a 68,2% da variação aleatória total, ao passo que a repetibilidade (variação intra-laboratorial) representou de 11,9 a 42,8% da reprodutibilidade. Os teores de PB estimados pelos laboratórios participantes são dependentes do efeito de interação do material avaliado e do laboratório, possível reflexo das várias diferenças entre os procedimentos utilizados por cada laboratório.

Collaborative study to evaluate the indigestible neutral detergent fiber and indigestible acid detergent fiber contents in feeds by in situ procedure / Estudo colaborativo para avaliação dos teores de fibra em detergente neutro indigestível e fibra em detergente ácido indigestível em alimentos por procedimento in situ

The objective of this collaborative study was to evaluate the indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF) content in feeds in six laboratories from institutions linked to the National Institute of Science and Technology in Animal Science (INCT-CA). Six feeds were evaluated: signal grass hay, sugarcane, corn silage, soybean meal, corn and citrus pulp. Estimated levels of iNDF and iADF proved to be dependent on the laboratory in which the analysis was performed. It was found that differences between laboratories ranged from 2.40 percentage points for soybean meal to 8.05 percentage points for sugarcane for iNDF analysis and from 1.79 percentage points for corn to 10.06 percentage points for hay for iADF analysis. It was observed that the individual evaluation of each material, the total random variation of the results between laboratories ranged from 88.75 to 96.77% and 88.75 to 98.40% for iNDF and iADF analysis, respectively. The iNDF and iADF levels are dependent on the interaction effect between the evaluated material and laboratory and have low reproducibility; this may be a consequence of the differences between the methods practiced by each laboratory, demonstrating lack of standardization of procedures used by the laboratories.

Objetivou-se conduzir estudo colaborativo para avaliação dos teores de fibra em detergente neutro indigestível (FDNi) e fibra em detergente ácido indigestível (FDAi) em alimentos em seis laboratórios de instituições integrantes do Instituto Nacional de Ciência e Tecnologia de Ciência Animal (INCTCA). Avaliaram-se seis alimentos: feno de capim-braquiária, cana-de-açúcar, silagem de milho, farelo de soja, milho grão e polpa cítrica. Os teores estimados de FDNi e FDAi se mostraram dependentes do laboratório em que a análise foi realizada. Verificou-se que as diferenças entre laboratórios variaram de 2,40 pontos percentuais para o farelo de soja a 8,05 pontos percentuais para a cana-de-açúcar para a análise de FDNi e de 1,79 ponto percentual para o milho a 10,06 pontos percentuais para o feno para a análise de FDAi. Observou-se que na avaliação individual de cada material, a variação aleatória total dos resultados entre laboratórios correspondeu de 88,75 a 96,77% e de 88,75 a 98,40% para as análises de FDNi e FDAi, respectivamente. Os teores de FDNi e FDAi são dependentes do efeito de interação do material avaliado e do laboratório e apresentam baixa reprodutibilidade, possível reflexo das diferenças entre os métodos praticados por cada laboratório, demonstrando falta de padronização dos procedimentos adotados pelos laboratórios.

Energy and protein requirements of crossbred Holstein x Zebu steers fed different levels of calcium and phosphorus in the diet / Exigências de energia e proteína de bovinos castrados mestiços Holandês x Zebu alimentados com diferentes níveis de cálcio e fósforo na dieta

The aim of this study was to determine the energy and protein requirements of crossbred Holstein x Zebu steers fed with or without the supplementation of dicalcium phosphate in the diet. Thirty-two steers with an average initial body weight of 377.5 ± 49.4 kg were used, of which four were initially slaughtered to estimate the empty body weight (EBW) of the animals. Twenty-four steers were fed ad libitum and were distributed in a completely randomized design with two levels of concentrate (30 and 60 %), and diets with or without dicalcium phosphate and four steers were fed at maintenance level, so that the body weight gain was equal to zero. After 84 days the animals were slaughtered. The animal tissues were sampled, and composted by two samples, denominated by carcass (bone, muscle and fat) and non-carcass (head, limbs, blood, hide, organs and viscera) for determination of the body composition. The net energy requirements (NEm) and metabolizable energy for maintenance (MEm) were obtained while relating heat production (HP) and metabolizable energy intake (MEI); meanwhile, the net energy requirements for gain (NEg) and the net protein requirements for gain (NPg) were obtained as a function of empty body weight (EBW), empty body gain (EBG) and retained energy (RE) in EBW. The daily net and metabolizable energy requirements for maintenance were 76.90 and 119.36 kcal/EBW0.75, r

Objetivou-se determinar as exigências nutricionais de energia e proteína para bovinos castrados mestiços Holandês x Zebu alimentados com ou sem suplementação inorgânica de cálcio e fósforo na dieta. Foram utilizados 32 animais mestiços Holandês × Zebu, machos, castrados, com peso corporal (BW) médio inicial de 377,5 ± 49,4 kg, dos quais quatro foram abatidos inicialmente para estimar o peso de corpo vazio (EBW) dos demais, 24 alimentados ad libitum distribuídos em delineamento inteiramente casualizado com dois níveis de concentrado (30 e 60%) e dietas contendo ou não fosfato bicálcico; e quatro alimentados ao nível de mantença, isto é, para que o ganho de peso corporal fosse igual a zero. Após 84 dias os animais foram abatidos. Para determinação da composição corporal dos animais, foram constituídas duas amostras por animal, denominadas carcaça (óssos, musculo e gordura) e não carcaça (cabeça, membros, sangue, couro, orgãos e visceras). As exigências de energia líquida (NEm) e metabolizável para mantença (MEm) foram obtidas relacionando a produção de calor (HP) e o consumo de energia metabolizável (MEI), enquanto as exigências de energia líquidas para ganho de peso (NEg) e as exigências líquidas de proteína para ganho (NPg) foram obtidas em função do EBW, do ganho de peso de corpo vazio (EBG), e da energia retida (RE) no EBW. As exigências diárias de energia líquida e metab

Collaborative study to evaluate the indigestible neutral detergent fiber and indigestible acid detergent fiber contents in feeds by in situ procedure / Estudo colaborativo para avaliação dos teores de fibra em detergente neutro indigestível e fibra em detergente ácido indigestível em alimentos por procedimento in situ

The objective of this collaborative study was to evaluate the indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF) content in feeds in six laboratories from institutions linked to the National Institute of Science and Technology in Animal Science (INCT-CA). Six feeds were evaluated: signal grass hay, sugarcane, corn silage, soybean meal, corn and citrus pulp. Estimated levels of iNDF and iADF proved to be dependent on the laboratory in which the analysis was performed. It was found that differences between laboratories ranged from 2.40 percentage points for soybean meal to 8.05 percentage points for sugarcane for iNDF analysis and from 1.79 percentage points for corn to 10.06 percentage points for hay for iADF analysis. It was observed that the individual evaluation of each material, the total random variation of the results between laboratories ranged from 88.75 to 96.77% and 88.75 to 98.40% for iNDF and iADF analysis, respectively. The iNDF and iADF levels are dependent on the interaction effect between the evaluated material and laboratory and have low reproducibility; this may be a consequence of the differences between the methods practiced by each laboratory, demonstrating lack of standardization of procedures used by the laboratories.

Objetivou-se conduzir estudo colaborativo para avaliação dos teores de fibra em detergente neutro indigestível (FDNi) e fibra em detergente ácido indigestível (FDAi) em alimentos em seis laboratórios de instituições integrantes do Instituto Nacional de Ciência e Tecnologia de Ciência Animal (INCTCA). Avaliaram-se seis alimentos: feno de capim-braquiária, cana-de-açúcar, silagem de milho, farelo de soja, milho grão e polpa cítrica. Os teores estimados de FDNi e FDAi se mostraram dependentes do laboratório em que a análise foi realizada. Verificou-se que as diferenças entre laboratórios variaram de 2,40 pontos percentuais para o farelo de soja a 8,05 pontos percentuais para a cana-de-açúcar para a análise de FDNi e de 1,79 ponto percentual para o milho a 10,06 pontos percentuais para o feno para a análise de FDAi. Observou-se que na avaliação individual de cada material, a variação aleatória total dos resultados entre laboratórios correspondeu de 88,75 a 96,77% e de 88,75 a 98,40% para as análises de FDNi e FDAi, respectivamente. Os teores de FDNi e FDAi são dependentes do efeito de interação do material avaliado e do laboratório e apresentam baixa reprodutibilidade, possível reflexo das diferenças entre os métodos praticados por cada laboratório, demonstrando falta de padronização dos procedimentos adotados pelos laboratórios.

Energy and protein requirements of crossbred Holstein x Zebu steers fed different levels of calcium and phosphorus in the diet / Exigências de energia e proteína de bovinos castrados mestiços Holandês x Zebu alimentados com diferentes níveis de cálcio e fósforo na dieta

The aim of this study was to determine the energy and protein requirements of crossbred Holstein x Zebu steers fed with or without the supplementation of dicalcium phosphate in the diet. Thirty-two steers with an average initial body weight of 377.5 ± 49.4 kg were used, of which four were initially slaughtered to estimate the empty body weight (EBW) of the animals. Twenty-four steers were fed ad libitum and were distributed in a completely randomized design with two levels of concentrate (30 and 60 %), and diets with or without dicalcium phosphate and four steers were fed at maintenance level, so that the body weight gain was equal to zero. After 84 days the animals were slaughtered. The animal tissues were sampled, and composted by two samples, denominated by carcass (bone, muscle and fat) and non-carcass (head, limbs, blood, hide, organs and viscera) for determination of the body composition. The net energy requirements (NEm) and metabolizable energy for maintenance (MEm) were obtained while relating heat production (HP) and metabolizable energy intake (MEI); meanwhile, the net energy requirements for gain (NEg) and the net protein requirements for gain (NPg) were obtained as a function of empty body weight (EBW), empty body gain (EBG) and retained energy (RE) in EBW. The daily net and metabolizable energy requirements for maintenance were 76.90 and 119.36 kcal/EBW0.75, r

Objetivou-se determinar as exigências nutricionais de energia e proteína para bovinos castrados mestiços Holandês x Zebu alimentados com ou sem suplementação inorgânica de cálcio e fósforo na dieta. Foram utilizados 32 animais mestiços Holandês × Zebu, machos, castrados, com peso corporal (BW) médio inicial de 377,5 ± 49,4 kg, dos quais quatro foram abatidos inicialmente para estimar o peso de corpo vazio (EBW) dos demais, 24 alimentados ad libitum distribuídos em delineamento inteiramente casualizado com dois níveis de concentrado (30 e 60%) e dietas contendo ou não fosfato bicálcico; e quatro alimentados ao nível de mantença, isto é, para que o ganho de peso corporal fosse igual a zero. Após 84 dias os animais foram abatidos. Para determinação da composição corporal dos animais, foram constituídas duas amostras por animal, denominadas carcaça (óssos, musculo e gordura) e não carcaça (cabeça, membros, sangue, couro, orgãos e visceras). As exigências de energia líquida (NEm) e metabolizável para mantença (MEm) foram obtidas relacionando a produção de calor (HP) e o consumo de energia metabolizável (MEI), enquanto as exigências de energia líquidas para ganho de peso (NEg) e as exigências líquidas de proteína para ganho (NPg) foram obtidas em função do EBW, do ganho de peso de corpo vazio (EBG), e da energia retida (RE) no EBW. As exigências diárias de energia líquida e metab

Estudo colaborativo para avaliação dos teores de matéria seca em alimentos

AbstractThe objective was to conduct a collaborative study to evaluate the dry matter contents in feeds in six feed analysis laboratories from institutions linked to the National Institute of Science and Technology in Animal Science (INCT-CA). Six feeds were evaluated: sugarcane, corn silage, elephant grass, soybean meal, citrus pulp, and corn mixed with urea (9:1). It was asked to each laboratory that the samples were analyzed for eleven days, consecutive or not, with three replicates per sample per day of evaluation. There were variations among laboratories, days of analysis and interaction effect of material and laboratory. Comparative evaluation between the average contents produced by the laboratories and the Karl Fischer method indicated that 11.1% of the assessments were found accurate. The variation of results among laboratories accounted from 54.1 to 79.2% of the total random variation. It was found that the repeatability represented 6.24 to 26.45% of reproducibility. There are Horwitz ratios less than 2 for all materials tested. It was noticed that 52.8% of the assessments show variations of the estimates as a function of days in which analysis was performed. High inter-laboratory variability was checked through the evaluation of questionnaires sent to laboratories to elucidate the main procedures used in each laboratory, which can possible explain the great variation of the estimates obtained here.

ResumoObjetivou-se conduzir estudo colaborativo para avaliação do teor de matéria seca em alimentos em seis laboratórios de análise de alimentos de instituições integrantes do Instituto Nacional de Ciência e Tecnologia de Ciência Animal (INCT-CA). Avaliaram-se seis alimentos: cana-de-açúcar, silagem de milho, capim-elefante, farelo de soja, polpa cítrica e mistura de milho grão com ureia (9:1). Solicitou-se a cada laboratório análises das amostras por onze dias, consecutivos ou não, sendo realizadas três repetições por amostra por dia de avaliação. Observou-se variação entre laboratórios, dias de análise e efeito de interação de material e laboratório. Avaliação comparativa das médias produzidas pelos laboratórios e pelo método de Karl Fischer indicou que 11,1% das avaliações foram exatas. A variação dos resultados entre laboratórios correspondeu de 54,1 a 79,2% da variação aleatória total. Verificou-se que a repetibilidade representou de 6,24 a 26,45% da reprodutibilidade. Observou-se razões de Horwitz inferiores a 2 para os materiais avaliados. Percebeu-se que 52,8% das avaliações apresentaram variações das estimativas em função do dia no qual a análise foi realizada. Elevada variabilidade inter-laboratorial foi verificada por intermédio da avaliação dos questionários enviados aos laboratórios para elucidação dos principais procedimentos adotados, evidenciando possíveis causas da alta variação dos resultados.

Feed efficiency and meat quality of crossbred beef heifers classified according to residual feed intake

AbstractThis study aimed to evaluate feed efficiency and meat quality of 31 three-crossbred beef heifers during 84 days in a feedlot system. A 60:40 concentrate and sorghum silage ration on DM basis (ME = 2.73Mcal/kg of DM, CP = 11.90% DM) was fed ad libitum. Based on residual feed intake (RFI) calculations, the heifers were ranked in three groups of feed efficiency: High RFI (average mean = 0.776; n = 9), medium RFI (average mean = -0.010; n = 11), and low RFI (average mean = - 0.624; n = 11). High RFI heifers consumed 4.56% more DM per day than low RFI heifers (P 0.05). The ADG did not differ (P> 0.05) among RFI groups (1.40kg/day). No differences (P>0.05) were detected for digestibility of the nutrients: DM (64.00%), CP (60.01%), crude fat (72.90%), NDF (54.80%) and non-fibrous carbohydrate (NFC) (78.91%). There were no differences between low and high RFI groups for slaughter weight (475.00 vs. 479.55kg), hot carcass weight (259.09 vs. 261.44kg), Longissimus dorsi (LD) area (69.02 vs. 68.11 cm2), back-fat thickness (5.74 vs. 6.26 cm), shear force (5.45 vs. 5.19kg), sensorial traits of LD muscle, LD color (intensities L=40.47 a*=24.74 and b*=16.13) or commercial cuts yield. Low RFI heifers presented similar meat quality and carcass traits as high RFI heifers, however low RFI heifers consumed less DM (kg/d).

ResumoO objetivo com este estudo foi avaliar a eficiência alimentar, qualidade da carne e digestibilidade dos nutrientes em 31 novilhas de corte mestiças durante 84 dias de confinamento. A relação volumoso:concentrado da dieta oferecidaad libitumfoi de 60:40 (EM= 2,73 Mcal/kg MS, PB= 11,90% MS). Baseado no consumo alimentar residual (CAR), os animais foram classificados em três grupos de eficiência alimentar: Alto CAR (média= 0,776; n = 9), médio CAR (média= -0,010; n = 11) e baixo CAR (média = - 0,624; n = 11). Novilhas alto CAR consumiram 4,56% a mais de MS diária comparadas à novilhas baixo CAR (P 0,05). O ganho médio diário não diferiu (P>0,05) entre animais de diferentes grupos de eficiência (1,40kg/dia). Não houveram diferenças para a digestibilidade dos nutrientes entre os grupos avaliados: MS (64,00%), PB (60,01%), EE (72,90%), FDN (54,80%) e CNF (78,91%). Não houveram diferenças entre alto e baixo CAR para peso ao abate (475,00 vs. 479,55kg), peso de carcaça quente (259,09 vs. 261,44kg), área do músculo Longissimus dorsi(LD) (69,02 vs. 68,11 cm2), espessura de gordura subcutânea (5,74 vs. 6,26cm), maciez (5,45 vs. 5,19kg), características sensoriais do músculo LD, coloração do músculo LD (intensidades L=40,47 a*=24,74 e b*=16,13) ou rendimento de cortes comerciais. Novilhas baixo CAR apresentaram similar qualidade de carcaça e carne à novilhas classificadas como alto CAR, entretanto novilhas baixo CAR apresentaram um menor consumo de MS (kg/d).

Feed efficiency and meat quality of crossbred beef heifers classified according to residual feed intake

AbstractThis study aimed to evaluate feed efficiency and meat quality of 31 three-crossbred beef heifers during 84 days in a feedlot system. A 60:40 concentrate and sorghum silage ration on DM basis (ME = 2.73Mcal/kg of DM, CP = 11.90% DM) was fed ad libitum. Based on residual feed intake (RFI) calculations, the heifers were ranked in three groups of feed efficiency: High RFI (average mean = 0.776; n = 9), medium RFI (average mean = -0.010; n = 11), and low RFI (average mean = - 0.624; n = 11). High RFI heifers consumed 4.56% more DM per day than low RFI heifers (P 0.05). The ADG did not differ (P> 0.05) among RFI groups (1.40kg/day). No differences (P>0.05) were detected for digestibility of the nutrients: DM (64.00%), CP (60.01%), crude fat (72.90%), NDF (54.80%) and non-fibrous carbohydrate (NFC) (78.91%). There were no differences between low and high RFI groups for slaughter weight (475.00 vs. 479.55kg), hot carcass weight (259.09 vs. 261.44kg), Longissimus dorsi (LD) area (69.02 vs. 68.11 cm2), back-fat thickness (5.74 vs. 6.26 cm), shear force (5.45 vs. 5.19kg), sensorial traits of LD muscle, LD color (intensities L=40.47 a*=24.74 and b*=16.13) or commercial cuts yield. Low RFI heifers presented similar meat quality and carcass traits as high RFI heifers, however low RFI heifers consumed less DM (kg/d).

ResumoO objetivo com este estudo foi avaliar a eficiência alimentar, qualidade da carne e digestibilidade dos nutrientes em 31 novilhas de corte mestiças durante 84 dias de confinamento. A relação volumoso:concentrado da dieta oferecidaad libitumfoi de 60:40 (EM= 2,73 Mcal/kg MS, PB= 11,90% MS). Baseado no consumo alimentar residual (CAR), os animais foram classificados em três grupos de eficiência alimentar: Alto CAR (média= 0,776; n = 9), médio CAR (média= -0,010; n = 11) e baixo CAR (média = - 0,624; n = 11). Novilhas alto CAR consumiram 4,56% a mais de MS diária comparadas à novilhas baixo CAR (P 0,05). O ganho médio diário não diferiu (P>0,05) entre animais de diferentes grupos de eficiência (1,40kg/dia). Não houveram diferenças para a digestibilidade dos nutrientes entre os grupos avaliados: MS (64,00%), PB (60,01%), EE (72,90%), FDN (54,80%) e CNF (78,91%). Não houveram diferenças entre alto e baixo CAR para peso ao abate (475,00 vs. 479,55kg), peso de carcaça quente (259,09 vs. 261,44kg), área do músculo Longissimus dorsi(LD) (69,02 vs. 68,11 cm2), espessura de gordura subcutânea (5,74 vs. 6,26cm), maciez (5,45 vs. 5,19kg), características sensoriais do músculo LD, coloração do músculo LD (intensidades L=40,47 a*=24,74 e b*=16,13) ou rendimento de cortes comerciais. Novilhas baixo CAR apresentaram similar qualidade de carcaça e carne à novilhas classificadas como alto CAR, entretanto novilhas baixo CAR apresentaram um menor consumo de MS (kg/d).

Estudo colaborativo para avaliação dos teores de matéria seca em alimentos

AbstractThe objective was to conduct a collaborative study to evaluate the dry matter contents in feeds in six feed analysis laboratories from institutions linked to the National Institute of Science and Technology in Animal Science (INCT-CA). Six feeds were evaluated: sugarcane, corn silage, elephant grass, soybean meal, citrus pulp, and corn mixed with urea (9:1). It was asked to each laboratory that the samples were analyzed for eleven days, consecutive or not, with three replicates per sample per day of evaluation. There were variations among laboratories, days of analysis and interaction effect of material and laboratory. Comparative evaluation between the average contents produced by the laboratories and the Karl Fischer method indicated that 11.1% of the assessments were found accurate. The variation of results among laboratories accounted from 54.1 to 79.2% of the total random variation. It was found that the repeatability represented 6.24 to 26.45% of reproducibility. There are Horwitz ratios less than 2 for all materials tested. It was noticed that 52.8% of the assessments show variations of the estimates as a function of days in which analysis was performed. High inter-laboratory variability was checked through the evaluation of questionnaires sent to laboratories to elucidate the main procedures used in each laboratory, which can possible explain the great variation of the estimates obtained here.

ResumoObjetivou-se conduzir estudo colaborativo para avaliação do teor de matéria seca em alimentos em seis laboratórios de análise de alimentos de instituições integrantes do Instituto Nacional de Ciência e Tecnologia de Ciência Animal (INCT-CA). Avaliaram-se seis alimentos: cana-de-açúcar, silagem de milho, capim-elefante, farelo de soja, polpa cítrica e mistura de milho grão com ureia (9:1). Solicitou-se a cada laboratório análises das amostras por onze dias, consecutivos ou não, sendo realizadas três repetições por amostra por dia de avaliação. Observou-se variação entre laboratórios, dias de análise e efeito de interação de material e laboratório. Avaliação comparativa das médias produzidas pelos laboratórios e pelo método de Karl Fischer indicou que 11,1% das avaliações foram exatas. A variação dos resultados entre laboratórios correspondeu de 54,1 a 79,2% da variação aleatória total. Verificou-se que a repetibilidade representou de 6,24 a 26,45% da reprodutibilidade. Observou-se razões de Horwitz inferiores a 2 para os materiais avaliados. Percebeu-se que 52,8% das avaliações apresentaram variações das estimativas em função do dia no qual a análise foi realizada. Elevada variabilidade inter-laboratorial foi verificada por intermédio da avaliação dos questionários enviados aos laboratórios para elucidação dos principais procedimentos adotados, evidenciando possíveis causas da alta variação dos resultados.

Levels of supplementation for grazing beef heifers.

The objective of this experiment was to evaluate the effect of providing different levels of a supplement on the nutritional characteristics and productive performance of heifers on pasture during the rainy-dry transition and dry season in Brazil or tropical area. Thirty crossbred heifers with predominance of Zebu breed were used in a completely randomized experimental design. Treatments consisted of a mineral supplement and 0.5, 1.0, 1.5, or 2.0 kg/animal/d of a protein supplement containing 300 g crude protein (CP)/kg of dry matter (DM). In the rainy-dry transition season there was quadratic effect of the protein supplementation (p<0.10) on daily weight gain (DWG). A linear relationship (p<0.10) was found between increasing supplement intake and intakes of DM, organic matter (OM), crude protein (CP), ether extract (EE), non fibrous carbohydrates (NFC) and total digestible nutrients (TDN). Coefficients of apparent digestibility of CP, EE, and NFC increased linearly (p<0.10) with increasing supplement levels, but there was no effect on the DM apparent digestibility (p>0.10); the microbial efficiency (g CPmic/kg TDN) and the relationship of microbial nitrogen flow with nitrogen intake (g/g nitrogen intake) were negative linear profiles. In the dry season, the descriptive pattern least squares means showed a trend of stabilization of DWG from the supply of 0.98 kg of protein supplement; the intakes of DM, OM, CP, EE, NFC, and TDN showed increasing linear relationship (p<0.10) with protein supplement levels; the means of apparent digestibility coefficients of the different dietary fractions presented a linear-response-plateau (LRP); the microbial nitrogen flow (g/d) showed positive linear profile (p<0.10) for supplementation levels. It is concluded that supplementation improves the productive performance of grazing heifers and that 1.0 kg/d of supplement per animal gives the maximum increment of weight gain.

Requerimentos nutricionais de energia e proteína em bovinos / Nutrient requirements of energy and protein for Holstein × Zebu bulls finished in feedlot

Objetivou-se com este estudo estimar as exigências nutricionais de energia e proteína em bovinos cruzados (Holandês × Zebu). Um experimento de abate comparativo foi conduzido com 44 (24 meses) bovinos cruzados pesando 338± 39 kg. Os bovinos foram aleatoriamente separados como segue: quatro bovinos para o grupo referência, quatro bovinos para o grupo mantença e 36 bovinos alimentados ad libitum. Foram uilizadas a silagem de milho (SM) e a cana-de-açúcar in natura (CA) nas proporções de 60 ou 40% na base da matéria seca (MS) total das dietas. As seis dietas experimentais foram constituídas da seguinte forma: 1) 60 SM: 40% de concentrado (C) durante 84 dias; 2) 60SM: 40C (42 dias) e 40SM:60C (42 dias); 3) 40SM:60C (84 dias); 4) 60CA:40C (84 dias); 5) 60CA:40C (42 dias) e 40CA:60C (42 dias) e 6) 40CA:60C (84 dias). Ao final do experimento, todos os animais foram abatidos para determinação do peso de corpo vazio (PCVZ). Uma amostra compreendida entre a 9ª e a 11ª costelas da meia carcaça esquerda foi retirada e completamente dissecada para a estimação da composição química do PCVZ utilizando as equações descritas no BR-CORTE em 2010. Os dados foram analisados como modelos não lineares elaborados por médias do comando NLIN do SAS (versão 9.2), ajustados pelo método de Gauss-Newton. Para todos os testes, 0.05 foi utilizado como nível crítico de probabilidade para o erro tipo I. As exi

The objective of this study was to estimate the nutritional requirements of energy and protein in crossbred (Holstein × Zebu) bulls. An experiment of comparative slaughter was conducted with 44 (24 months old) crossbred bulls of 338 ± 39 kg. Bulls were randomly separated as follows: four bulls to the control group, four bulls to the maintenance level group and 36 bulls were fed ad libitum. Corn silage (CS) and sugar cane in natura (SC) at 60 or 40% of dry matter (DM) of total diets were utilized in the diets. The bulls of the last group were randomly assigned to one of six different diets: 1) 60CS:40C(84 days); 2) 60CS:40C (42 days) and 40CS:60C (42 days); 3) 40CS:60C (84 days); 4) 60SC:40C (84 days); 5) 60SC:40C (42 days), and 40SC:60C (42 days), and 6) 40SC:60C (84 days). At the end of the experiment, bulls were slaughtered at Universidade Federal de Viçosa for estimation of the empty body weight. One sample located between the 9th and the 11th ribs of each bull was taken and completely dissected for estimation of the empty body composition using equations developed by BR-CORTE 2010. The data were analyzed as nonlinear models built by means of command NLIN of SAS (version 9.2), adjusted by the method of Gauss-Newton. For all the tests, 0.05 was utilized as critical level for probability of type I error. The net (NEm) and metabolizable (MEm) energy requirements for maintenance

Requerimentos nutricionais de energia e proteína em bovinos / Nutrient requirements of energy and protein for Holstein × Zebu bulls finished in feedlot

Objetivou-se com este estudo estimar as exigências nutricionais de energia e proteína em bovinos cruzados (Holandês × Zebu). Um experimento de abate comparativo foi conduzido com 44 (24 meses) bovinos cruzados pesando 338± 39 kg. Os bovinos foram aleatoriamente separados como segue: quatro bovinos para o grupo referência, quatro bovinos para o grupo mantença e 36 bovinos alimentados ad libitum. Foram uilizadas a silagem de milho (SM) e a cana-de-açúcar in natura (CA) nas proporções de 60 ou 40% na base da matéria seca (MS) total das dietas. As seis dietas experimentais foram constituídas da seguinte forma: 1) 60 SM: 40% de concentrado (C) durante 84 dias; 2) 60SM: 40C (42 dias) e 40SM:60C (42 dias); 3) 40SM:60C (84 dias); 4) 60CA:40C (84 dias); 5) 60CA:40C (42 dias) e 40CA:60C (42 dias) e 6) 40CA:60C (84 dias). Ao final do experimento, todos os animais foram abatidos para determinação do peso de corpo vazio (PCVZ). Uma amostra compreendida entre a 9ª e a 11ª costelas da meia carcaça esquerda foi retirada e completamente dissecada para a estimação da composição química do PCVZ utilizando as equações descritas no BR-CORTE em 2010. Os dados foram analisados como modelos não lineares elaborados por médias do comando NLIN do SAS (versão 9.2), ajustados pelo método de Gauss-Newton. Para todos os testes, 0.05 foi utilizado como nível crítico de probabilidade para o erro tipo I. As exi

The objective of this study was to estimate the nutritional requirements of energy and protein in crossbred (Holstein × Zebu) bulls. An experiment of comparative slaughter was conducted with 44 (24 months old) crossbred bulls of 338 ± 39 kg. Bulls were randomly separated as follows: four bulls to the control group, four bulls to the maintenance level group and 36 bulls were fed ad libitum. Corn silage (CS) and sugar cane in natura (SC) at 60 or 40% of dry matter (DM) of total diets were utilized in the diets. The bulls of the last group were randomly assigned to one of six different diets: 1) 60CS:40C(84 days); 2) 60CS:40C (42 days) and 40CS:60C (42 days); 3) 40CS:60C (84 days); 4) 60SC:40C (84 days); 5) 60SC:40C (42 days), and 40SC:60C (42 days), and 6) 40SC:60C (84 days). At the end of the experiment, bulls were slaughtered at Universidade Federal de Viçosa for estimation of the empty body weight. One sample located between the 9th and the 11th ribs of each bull was taken and completely dissected for estimation of the empty body composition using equations developed by BR-CORTE 2010. The data were analyzed as nonlinear models built by means of command NLIN of SAS (version 9.2), adjusted by the method of Gauss-Newton. For all the tests, 0.05 was utilized as critical level for probability of type I error. The net (NEm) and metabolizable (MEm) energy requirements for maintenance

Voluntary intake and milk production in F1 Holstein × zebu cows in confinement.

The objective of this study was to evaluate the nutrient intake and milk production in Holstein × zebu (F1) cows in feedlot. Eighteen F1 cows were used, divided into three treatments; six were Holstein × Gir (HGI), six were Holstein × Guzerat (HGU), and another six were Holstein × Nelore (HNE), which had recently calved, distributed into simple, random samples, under the same feeding conditions of corn silage and concentrate with 20% crude protein. The three-marker method was used (LIPE, titanium dioxide, and iADF) to estimate the individual intake and digestibility of the nutrients for the cows in group. The mathematical model used to establish the lactation curves was: Y = at(b)e(-ct) by Wood (Nature 216:164-165, 1967). The statistical analyses for the nutrient intake and digestibility, as well as parameters of metabolic efficiency, were performed using multiple linear regression (α = 5%). No effect (P > 0.05) of genetic group was observed for any of the variables studied. The intake and digestibility of the nutrients and the microbial nitrogen presented quadratic curves as a function of the lactation period (P < 0.05). The HGU cows exhibited an accumulated milk production of 4,946.81 kg at 305 days, whereas the HGI cows produced 4,821.78 kg. The HNE cows displayed inferior performance, with a production of 3,674.98 kg. It was concluded that, in confinement, F1 cows from different genetic groups do not exhibit different intake, digestibility, or metabolic efficiency. The HGU and HGI cows have greater cumulative production at 305 days.