Particle size and storage length affect fermentation and ruminal degradation of rehydrated corn grain silage.

Particle size and storage time are factors that can affect the fermentation quality and digestibility of rehydrated corn grain silage (RCS). The objective of this study was to evaluate the effect of particle size and storage time on chemical and microbiological characteristics, aerobic stability, and ruminal degradability of RCS. Corn grains were ground to pass through either a 3 mm (fine) or 9 mm (coarse) screen, rehydrated to 44.3% moisture and ensiled in 200 L polyethylene buckets. Samples were taken before and after ensiling at 10, 30, 90 and 200 days of storage to assess microbial counts, fermentation end products, and DM ruminal degradability. DM degradation was evaluated with incubation times of 0 (bag wash), 3, 6 and 48 h in 3 rumen-cannulated cows. The effective ruminal degradation (ERD) was calculated based on soluble fraction (A), degradable fraction (B) and passage rate (kp) defined as 7.0%/h: A + B [kd/(kd + kp)]. Aerobic stability was evaluated in silages after 200 days of storage, and pH and temperature were analysed up to 240 h of aerobic exposure. At 90 and 200 d of storage, fine RCS resulted in lower crude protein and greater NH3-N concentrations than coarse RCS. Coarsely ground RCS had a lower temperature at the beginning of storage than finely ground corn. Finely ground RCS had greater yeast counts and ethanol concentrations than coarsely ground RCS during storage time. Fine RCS was more susceptible to aerobic deterioration, reaching maximum temperature and pH values faster than coarse RCS. DM ruminal degradability increased over the storage time. The particle size of the rehydrated corn grain silage did not affect the kd values after 90 d of storage, while for the ERD, a long fermentation time was necessary (200 d). Considering the fermentation characteristics and the kinetics of ruminal DM degradation, fine grinding is recommended for short storage periods and coarse grinding may be a strategy to increase the rate of grinding when the storage period is greater than 200 d.

How to use recombinant bovine somatotropin in crossbred Holstein × Gyr (3/4 and 7/8) cows?

The aim of this study was to evaluate the effects of dose, start time, and application interval of recombinant bovine somatotropin (rbST) on performance, health, and reproduction parameters of crossbred Holstein × Gyr dairy cows (3/4 and 7/8). A 2 × 2 × 2 factorial study was designed to test the effects of application dose (250 mg rbST or 500 mg rbST), start of application (40 or 63 days in milk (DIM)), and application interval (12 or 14 days); 180 crossbred Holstein × Gyr cows were enrolled. Treatments with 500 mg rbST resulted in increased milk production, 3.5% fat-corrected milk (FCM), and energy-corrected milk (ECM). In the factorial design analysis, greater FCM, ECM, and milk solid production (kg/day) were observed when 500 mg rbST was started at 63 DIM, while 250 mg rbST resulted in greater milk production (kg/day), FCM, ECM, and milk solids (kg/day) when administered at 12-day intervals. Administration of 500 mg rbST resulted in an increase of days open and number of services per pregnancy (P = 0.01). Holstein × Gyr cows (3/4 and 7/8) presented a superior productive response to rbST when treated with 500 mg starting at 63 DIM and at 14-day intervals.

Erratum to: A blend of essential oils improved feed efficiency and affected ruminal and systemic variables of dairy cows.

[This corrects the article DOI: 10.1093/tas/txz183.].

A blend of essential oils improved feed efficiency and affected ruminal and systemic variables of dairy cows.

This experiment evaluated the effect of a blend of essential oils (BEO) on intake, lactation performance, diet digestibility, ruminal fermentation profile, eating behavior, body thermoregulation, blood acid-base balance, and milk fatty acid profile of lactating cows. Twenty-eight Holstein cows were individually fed a standard diet for 14 d and treatments control or BEO (a microencapsulated blend of pepper extract containing capsaicin and pure forms of carvacrol, cinnamaldehyde, and eugenol; 150 mg/kg of diet dry matter) for 56 d. Significance was declared at P ≤ 0.05 and trends at 0.05 < P ≤ 0.10. Dry matter intake (DMI) was reduced (19.5 vs. 20.1 kg/d) and milk yield was increased (30.1 vs. 30.8 kg/d) by BEO, inducing improved milk to DMI ratio (1.53 vs. 1.62). Milk fat concentration tended to be increased by BEO, but total solids yield did not differ. There was a trend for increased total tract non-neutral detergent fiber organic matter digestibility with BEO. The molar proportion of acetate in ruminal fluid was reduced (51.4 vs. 57.8%) and that of propionate was increased (26.1 vs. 31.3%) by BEO. Ruminal microbial yield and total protozoa count in ruminal fluid did not differ. Cows fed BEO ingested a greater proportion of the daily intake in the morning (30.6 vs. 36.6%) and tended to ingest a lower proportion at night, tended to have longer meals, and had fewer meals per day (11.9 vs. 13.7) and larger meal size (1.5 vs. 1.7 kg of dry matter per meal). Blood urea-N and glucose concentrations did not differ. The BEO increased jugular blood oxygenation. The sweating rate on a hot and dry day was increased (160 vs. 221 g/m2/h) by BEO. The mean rectal and skin temperatures and respiration rate did not differ, but the proportion of rectal temperature measurements ≥39.2 °C was reduced by BEO at 1400 h (17.8 vs. 28.5%) and 2000 h (23.2 vs. 34.8%). The BEO increased the secretion (g/d) of 18:2 trans-10, cis-12 and the concentration of 18:0 iso fatty acids in milk fat. When one sample of milk from BEO cows was offered with two samples of milk from control, 59% of regular consumers of milk (n = 63) identified the odd sample correctly. The gain in feed efficiency induced by BEO was associated with reduced acetate-to-propionate ratio in ruminal fluid, altered eating behavior, lower frequency of high rectal temperature, and increased blood oxygenation. Essential oils had positive effects on ruminal fermentation and systemic variables of dairy cows.

A survey of whole-plant corn silages from Minas Gerais dairy farms

Whole-plant corn silage (WPCS) is a commonly used forage for feeding dairy cattle in Brazil. The aim of this study was to evaluate on-farm ensilaging practices and the nutritional value, microbiology and fermentation profiles of WPCS from dairy farms in the south of the state of Minas Gerais, Brazil. Silages from 54 dairy farms located in nine cities were sampled and a questionnaire was distributed for completion to describe the herd profile and ensilage practices. Herd size ranged from 8 to 1,000 lactating cows, and 52 % of the farms had fewer than 50 cows in lactation. The majority of the farms cultivated hard endosperm texture hybrids (52 %) and used pull-type forage harvesters (87 %). Double-sided plastic was the most used form of silo sealing (56 %) and 28 % used inoculants. Lactic acid bacteria count was greater than 6.01 log CFU g1 in 60 % of the samples, and the mean populations of enterobacteria and Bacillus spp. were 4.23 and 4.09 log CFU g1, respectively. Silo size ranged from 100 to 250 m3 in 44 % of the farms, and the silage removal rate was below 15 cm of the face/d in 41 % of cases. Silage dry matter (DM) concentration was 33 ± 3 % of fresh matter, NDF concentration was 57 ± 7 % of the DM, and in vitro NDF digestibility was 35 ± 11 % of the NDF. Silages with high DM concentrations had large particle size, affecting the nutritional value and the fermentative pattern. Improvements in ensiling practices can potentially inhibit the growth of spoilage microorganisms and raise the nutritional value of silages.

A survey of whole-plant corn silages from Minas Gerais dairy farms

Whole-plant corn silage (WPCS) is a commonly used forage for feeding dairy cattle in Brazil. The aim of this study was to evaluate on-farm ensilaging practices and the nutritional value, microbiology and fermentation profiles of WPCS from dairy farms in the south of the state of Minas Gerais, Brazil. Silages from 54 dairy farms located in nine cities were sampled and a questionnaire was distributed for completion to describe the herd profile and ensilage practices. Herd size ranged from 8 to 1,000 lactating cows, and 52 % of the farms had fewer than 50 cows in lactation. The majority of the farms cultivated hard endosperm texture hybrids (52 %) and used pull-type forage harvesters (87 %). Double-sided plastic was the most used form of silo sealing (56 %) and 28 % used inoculants. Lactic acid bacteria count was greater than 6.01 log CFU g1 in 60 % of the samples, and the mean populations of enterobacteria and Bacillus spp. were 4.23 and 4.09 log CFU g1, respectively. Silo size ranged from 100 to 250 m3 in 44 % of the farms, and the silage removal rate was below 15 cm of the face/d in 41 % of cases. Silage dry matter (DM) concentration was 33 ± 3 % of fresh matter, NDF concentration was 57 ± 7 % of the DM, and in vitro NDF digestibility was 35 ± 11 % of the NDF. Silages with high DM concentrations had large particle size, affecting the nutritional value and the fermentative pattern. Improvements in ensiling practices can potentially inhibit the growth of spoilage microorganisms and raise the nutritional value of silages.(AU)

Effects of neutral detergent fiber concentration of sugarcane-based diets on the performance of Holstein heifers / Efeito do nível dietético de FDN de cana-de-açúcar sobre o desempenho de novilhas Holandesas

This study aimed to evaluate the effects of increasing the neutral detergent fibers (NDF) concentration of sugarcane-based diets on the growth and development of Holstein heifers. Twenty-seven Holstein heifers with a mean body weight of 265.5 ± 36.4 kg were housed in a sand bedded tie stall and fed individually. The experimental diet consisted of fresh sugarcane and concentrate. Three concentrations of sugarcane NDF were compared: 33% (SC33), 38% (SC38), and 42% (SC42). Crude protein content of experimental diets was 16%. The following parameters were evaluated: dry matter intake, weight gain and morphometric measures, digestibility, feeding behavior, and ruminal pH. The experimental design was a randomized block and all analyses were performed using the MIXED procedure in SAS. Intake of DM decreased as NDF concentration increased (p=0.07), but weight gain and growth were not significantly affected (p=0.74). As dietary NDF increased, chewing activity per unit DM intake increased (p=0.001), but rumen pH was not significantly affected (p=0.91). Diets formulated with 330?420 g of sugarcane NDF/kg of dry matter were sufficient to support the growth of Holstein heifers.(AU)

O objetivo foi avaliar dietas com diferentes teores de FDN oriundos de cana-de-açúcar no crescimento e desenvolvimento de novilhas Holandesas. Os animais experimentais foram vinte e sete novilhas da raça Holandesa pesando em média 265,5 +- 36,4 kg, alojadas em um Tie Stall com camas de areia e alimentadas individualmente. A ração experimental total era composta por cana-de-açúcar e concentrado. Testou três concentrações dietéticas de FDN oriundo da cana-de-açúcar: 33% de FDN (SC33); 38% FDN (SC38) e 42% FDN (SC42). O teor de proteína bruta da ração foi de 16%. Foram avaliados consumo de matéria seca, ganho de peso e parâmetros corporais, digestibilidade, comportamento alimentar e pH ruminal. O delineamento foi em blocos casualizados, e a analise estatísticas pelo proc MIXED do programa SAS. O consumo de matéria seca foi menor com o aumento de FDN da dieta (P=0,07), mas isso não interferiu no ganho de peso e crescimento dos animais (P=0,74). A maior inclusão de FDN na ração resultou em aumento na atividade mastigatória por unidade de matéria seca ingerida (P=0,001) e não interferiu no pH (P=0,91). Pode-se concluir que rações formuladas com até 420 gramas de FDN oriundo de cana-de-açúcar por kg de matéria seca dietética foram adequadas à fase de crescimento de novilhas Holandesas.(AU)

Effects of neutral detergent fiber concentration of sugarcane-based diets on the performance of Holstein heifers / Efeito do nível dietético de FDN de cana-de-açúcar sobre o desempenho de novilhas Holandesas

This study aimed to evaluate the effects of increasing the neutral detergent fibers (NDF) concentration of sugarcane-based diets on the growth and development of Holstein heifers. Twenty-seven Holstein heifers with a mean body weight of 265.5 ± 36.4 kg were housed in a sand bedded tie stall and fed individually. The experimental diet consisted of fresh sugarcane and concentrate. Three concentrations of sugarcane NDF were compared: 33% (SC33), 38% (SC38), and 42% (SC42). Crude protein content of experimental diets was 16%. The following parameters were evaluated: dry matter intake, weight gain and morphometric measures, digestibility, feeding behavior, and ruminal pH. The experimental design was a randomized block and all analyses were performed using the MIXED procedure in SAS. Intake of DM decreased as NDF concentration increased (p=0.07), but weight gain and growth were not significantly affected (p=0.74). As dietary NDF increased, chewing activity per unit DM intake increased (p=0.001), but rumen pH was not significantly affected (p=0.91). Diets formulated with 330?420 g of sugarcane NDF/kg of dry matter were sufficient to support the growth of Holstein heifers.

O objetivo foi avaliar dietas com diferentes teores de FDN oriundos de cana-de-açúcar no crescimento e desenvolvimento de novilhas Holandesas. Os animais experimentais foram vinte e sete novilhas da raça Holandesa pesando em média 265,5 +- 36,4 kg, alojadas em um Tie Stall com camas de areia e alimentadas individualmente. A ração experimental total era composta por cana-de-açúcar e concentrado. Testou três concentrações dietéticas de FDN oriundo da cana-de-açúcar: 33% de FDN (SC33); 38% FDN (SC38) e 42% FDN (SC42). O teor de proteína bruta da ração foi de 16%. Foram avaliados consumo de matéria seca, ganho de peso e parâmetros corporais, digestibilidade, comportamento alimentar e pH ruminal. O delineamento foi em blocos casualizados, e a analise estatísticas pelo proc MIXED do programa SAS. O consumo de matéria seca foi menor com o aumento de FDN da dieta (P=0,07), mas isso não interferiu no ganho de peso e crescimento dos animais (P=0,74). A maior inclusão de FDN na ração resultou em aumento na atividade mastigatória por unidade de matéria seca ingerida (P=0,001) e não interferiu no pH (P=0,91). Pode-se concluir que rações formuladas com até 420 gramas de FDN oriundo de cana-de-açúcar por kg de matéria seca dietética foram adequadas à fase de crescimento de novilhas Holandesas.

Replacement of raw soybean with roasted soybean increased milk production in Holstein cows / Substituição de soja crua por soja tostada aumentou a produção de leite em vacas da raça Holandesa

The aim of this study was to evaluate the effect of total replacement of raw whole soybean (RAW) for roastedwhole soybean (ROS) on the production performance of Holstein cows. Two experiments were carried out usinga simple reversal design where RAW has been completely replaced by ROS. In experiment 1, 22 cows (175±60 days in milk)were used, and the dietary inclusion level of RAW or ROS was 3.7% of dry matter (DM). In experiment 2, 16 cows (130±50 days in milk)were used, and thedietary inclusion level of RAW or ROS was 11% of DM. In both experiments, ROS increased milk production by 1.1kgday-1 without changing fat and protein production. Dry matter intake or milk urea nitrogenwere not affected by dietary soy source. In experiment 2, plasma glucose concentration was decreased, and allantoin/creatinine ratio in urine tended to decreasein ROS. Experiment 2 also evaluated the nutrient digestibility and ruminal degradation kinetics of crude protein in two soybean sources. Roasting had no effect on the digestibility of DM, organic matter, and neutral detergent fiber. Roasted whole soybean hadgreater fraction B and lower protein degradation rate than did RAW; this showed that heat treatment was effective in increasing therumen undegradable amino acid flowto the animal, which suggesteda potential mechanism of action for improved performance observed in ROS.

O objetivo deste estudo foi avaliar o efeito da substituição total de soja integral crua (SC) por soja integral tostada (ST) sobre o desempenho produtivo de vacas Holandês. Foram realizados dois experimentos com delineamento experimental de reversão simples nos quais a SC foi totalmente substituída por ST. No experimento 1, foram utilizadas 22 vacas (175±60DEL) e o nível de inclusão dietética de SC ou ST foi de 3,7% na matéria seca (MS). No experimento 2, foram utilizadas 16 vacas (130±50 DEL) e o nível de inclusão dietético de SC ou ST foi de 11% na MS. Em ambos os experimentos, ST aumentou a produção de leite em 1,1kgd-1, sem alterar as produções de gordura e proteína. O consumo de MS e nitrogênio uréico no leite não foram afetados pela fonte de soja dietética. No experimento 2, a concentração de glicose plasmática foi reduzida e a relação alantoína/creatinina na urina tendeu a ser reduzida por ST. O experimento 2 também avaliou digestibilidade de nutrientes e cinética de degradação ruminal da proteína bruta das duas fontes de soja. Não houve efeito da tostagem nas digestibilidades da MS, matéria orgânica e FDN. A ST apresentou maior fração B e menor taxa de degradação da proteína do que a SC, mostrando que o tratamento térmico foi efetivo em aumentar o fluxo de aminoácidosnão degradáveis no rúmen para o animal, sugerindo um potencial mecanismo de ação para a melhora no desempenho observada com ST.

Replacement of raw soybean with roasted soybean increased milk production in Holstein cows / Substituição de soja crua por soja tostada aumentou a produção de leite em vacas da raça Holandesa

The aim of this study was to evaluate the effect of total replacement of raw whole soybean (RAW) for roastedwhole soybean (ROS) on the production performance of Holstein cows. Two experiments were carried out usinga simple reversal design where RAW has been completely replaced by ROS. In experiment 1, 22 cows (175±60 days in milk)were used, and the dietary inclusion level of RAW or ROS was 3.7% of dry matter (DM). In experiment 2, 16 cows (130±50 days in milk)were used, and thedietary inclusion level of RAW or ROS was 11% of DM. In both experiments, ROS increased milk production by 1.1kgday-1 without changing fat and protein production. Dry matter intake or milk urea nitrogenwere not affected by dietary soy source. In experiment 2, plasma glucose concentration was decreased, and allantoin/creatinine ratio in urine tended to decreasein ROS. Experiment 2 also evaluated the nutrient digestibility and ruminal degradation kinetics of crude protein in two soybean sources. Roasting had no effect on the digestibility of DM, organic matter, and neutral detergent fiber. Roasted whole soybean hadgreater fraction B and lower protein degradation rate than did RAW; this showed that heat treatment was effective in increasing therumen undegradable amino acid flowto the animal, which suggesteda potential mechanism of action for improved performance observed in ROS.(AU)

O objetivo deste estudo foi avaliar o efeito da substituição total de soja integral crua (SC) por soja integral tostada (ST) sobre o desempenho produtivo de vacas Holandês. Foram realizados dois experimentos com delineamento experimental de reversão simples nos quais a SC foi totalmente substituída por ST. No experimento 1, foram utilizadas 22 vacas (175±60DEL) e o nível de inclusão dietética de SC ou ST foi de 3,7% na matéria seca (MS). No experimento 2, foram utilizadas 16 vacas (130±50 DEL) e o nível de inclusão dietético de SC ou ST foi de 11% na MS. Em ambos os experimentos, ST aumentou a produção de leite em 1,1kgd-1, sem alterar as produções de gordura e proteína. O consumo de MS e nitrogênio uréico no leite não foram afetados pela fonte de soja dietética. No experimento 2, a concentração de glicose plasmática foi reduzida e a relação alantoína/creatinina na urina tendeu a ser reduzida por ST. O experimento 2 também avaliou digestibilidade de nutrientes e cinética de degradação ruminal da proteína bruta das duas fontes de soja. Não houve efeito da tostagem nas digestibilidades da MS, matéria orgânica e FDN. A ST apresentou maior fração B e menor taxa de degradação da proteína do que a SC, mostrando que o tratamento térmico foi efetivo em aumentar o fluxo de aminoácidosnão degradáveis no rúmen para o animal, sugerindo um potencial mecanismo de ação para a melhora no desempenho observada com ST.(AU)

Replacement of raw soybean with roasted soybean increased milk production in Holstein cows / Substituição de soja crua por soja tostada aumentou a produção de leite em vacas da raça Holandesa

ABSTRACT: The aim of this study was to evaluate the effect of total replacement of raw whole soybean (RAW) for roastedwhole soybean (ROS) on the production performance of Holstein cows. Two experiments were carried out usinga simple reversal design where RAW has been completely replaced by ROS. In experiment 1, 22 cows (175±60 days in milk)were used, and the dietary inclusion level of RAW or ROS was 3.7% of dry matter (DM). In experiment 2, 16 cows (130±50 days in milk)were used, and thedietary inclusion level of RAW or ROS was 11% of DM. In both experiments, ROS increased milk production by 1.1kgday-1 without changing fat and protein production. Dry matter intake or milk urea nitrogenwere not affected by dietary soy source. In experiment 2, plasma glucose concentration was decreased, and allantoin/creatinine ratio in urine tended to decreasein ROS. Experiment 2 also evaluated the nutrient digestibility and ruminal degradation kinetics of crude protein in two soybean sources. Roasting had no effect on the digestibility of DM, organic matter, and neutral detergent fiber. Roasted whole soybean hadgreater fraction B and lower protein degradation rate than did RAW; this showed that heat treatment was effective in increasing therumen undegradable amino acid flowto the animal, which suggesteda potential mechanism of action for improved performance observed in ROS.

RESUMO: O objetivo deste estudo foi avaliar o efeito da substituição total de soja integral crua (SC) por soja integral tostada (ST) sobre o desempenho produtivo de vacas Holandês. Foram realizados dois experimentos com delineamento experimental de reversão simples nos quais a SC foi totalmente substituída por ST. No experimento 1, foram utilizadas 22 vacas (175±60DEL) e o nível de inclusão dietética de SC ou ST foi de 3,7% na matéria seca (MS). No experimento 2, foram utilizadas 16 vacas (130±50 DEL) e o nível de inclusão dietético de SC ou ST foi de 11% na MS. Em ambos os experimentos, ST aumentou a produção de leite em 1,1kgd-1, sem alterar as produções de gordura e proteína. O consumo de MS e nitrogênio uréico no leite não foram afetados pela fonte de soja dietética. No experimento 2, a concentração de glicose plasmática foi reduzida e a relação alantoína/creatinina na urina tendeu a ser reduzida por ST. O experimento 2 também avaliou digestibilidade de nutrientes e cinética de degradação ruminal da proteína bruta das duas fontes de soja. Não houve efeito da tostagem nas digestibilidades da MS, matéria orgânica e FDN. A ST apresentou maior fração B e menor taxa de degradação da proteína do que a SC, mostrando que o tratamento térmico foi efetivo em aumentar o fluxo de aminoácidosnão degradáveis no rúmen para o animal, sugerindo um potencial mecanismo de ação para a melhora no desempenho observada com ST.

Performance of calves submitted to protocols using extruded or ground starter

Feed processing can affect rumen development in new born calves, and potentially define animal performance. Two feed management systems, extruded starter (Ruter) with possible early weaning and ground starter (control), were evaluated in thirty-two Holstein calves (16 females and 16 males). Animals were randomly assigned to the treatments using a randomized block design with birth weight as a covariate. They were weaned when starter intake reached 800 g for two consecutive days. Twenty-one days after the weaning, males were slaughtered and the stomach compartments were isolated. Rumen and omasum fragments were processed for morphological evaluation. Animal performance, clinical condition and stomach compartment weight did not differ between the treatments (P> 0.05), despite weaning weight of animals receiving extruded starter being 5.68% higher than the control animals. Extruded starter stimulated cell proliferation of the ruminal epithelium (P <0.05), but did not affect the dimensions of the papillary rumen and omasum mitotic index (MI). The Ruter feeding system was potentially beneficial for weight gain and morphofunctional rumen development in lactating animals; however, this treatment did not allow early weaning as proposed by the feeding system.

Nutrição e reprodução em vacas leiteiras / Nutrition and reproduction in dairy cows

O período de transição é caracterizado por adaptações no metabolismo de lipídeos, carboidratos e proteínas, visando suprir a demanda por nutrientes da lactação. O balanço energético negativo se inicia poucos dias antes do parto e se agrava no pós-parto. Este é associado à atenuação da freqüência dos pulsos de LH, redução na concentração sanguínea de glicose, insulina e IGF-1, e aumento na concentração de ácidos graxos não esterificados e β-hidroxibutirato. O déficit energético pode reduzir a produção de estrógeno pelo folículo dominante, aumentar o intervalo do parto à primeira ovulação, e reduzir a concentração de progesterona no sangue e a qualidade de ovócitos e embriões. O fornecimento de dietas ricas em proteína é freqüentemente associado ao aumento da concentração de nitrogênio uréico no plasma, alterações no ambiente uterino e redução da viabilidade embrionária. O balanço energético negativo e o consumo de dietas ricas em proteína podem estar envolvidos no decréscimo da fertilidade em vacas leiteiras de alta produção. (AU)

The transition period is characterized by changes in lipid, carbohydrate, and protein metabolism, to meet the nutrient demand of lactation. The negative energy balance starts a few days before calving and is aggravated postpartum. It is associated to attenuation of LH pulse frequency, to reduced blood concentrations of glucose, insulin, and IGF-1 and increased concentrations of non-esterified fatty acids and β-hydroxybutyrate. Energy deficiency may reduce estrogen production by the dominant follicle, increase the interval from calving to first ovulation, and reduce blood progesterone concentration and oocytes and embryo quality. The supply of protein rich diets is often associated with increased plasma urea nitrogen content, changes in uterine environment and reduced embryo viability. The negative energy balance and the intake of protein rich diets may be involved in the decreased fertility of high-yielding dairy cows. (AU)

Nutrição e reprodução em vacas leiteiras / Nutrition and reproduction in dairy cows

O período de transição é caracterizado por adaptações no metabolismo de lipídeos, carboidratos e proteínas, visando suprir a demanda por nutrientes da lactação. O balanço energético negativo se inicia poucos dias antes do parto e se agrava no pós-parto. Este é associado à atenuação da freqüência dos pulsos de LH, redução na concentração sanguínea de glicose, insulina e IGF-1, e aumento na concentração de ácidos graxos não esterificados e β-hidroxibutirato. O déficit energético pode reduzir a produção de estrógeno pelo folículo dominante, aumentar o intervalo do parto à primeira ovulação, e reduzir a concentração de progesterona no sangue e a qualidade de ovócitos e embriões. O fornecimento de dietas ricas em proteína é freqüentemente associado ao aumento da concentração de nitrogênio uréico no plasma, alterações no ambiente uterino e redução da viabilidade embrionária. O balanço energético negativo e o consumo de dietas ricas em proteína podem estar envolvidos no decréscimo da fertilidade em vacas leiteiras de alta produção.

The transition period is characterized by changes in lipid, carbohydrate, and protein metabolism, to meet the nutrient demand of lactation. The negative energy balance starts a few days before calving and is aggravated postpartum. It is associated to attenuation of LH pulse frequency, to reduced blood concentrations of glucose, insulin, and IGF-1 and increased concentrations of non-esterified fatty acids and β-hydroxybutyrate. Energy deficiency may reduce estrogen production by the dominant follicle, increase the interval from calving to first ovulation, and reduce blood progesterone concentration and oocytes and embryo quality. The supply of protein rich diets is often associated with increased plasma urea nitrogen content, changes in uterine environment and reduced embryo viability. The negative energy balance and the intake of protein rich diets may be involved in the decreased fertility of high-yielding dairy cows.

Botulismo em bovinos leiteiros no Sul de Minas Gerais, Brasil / Botulism in dairy cattle in southern Minas Gerais, Brazil

Neste trabalho descreve-se um surto de botulismo decorrente da ingestão de milho contaminado em um sistema de produção de leite, em regime de confinamento, na região Sul de Minas Gerais. O rebanho era composto por 148 vacas holandesas lactantes de alta produção, confinadas em tempo integral e alimentadas com dieta completa, composta de silagem de milho e concentrado. Foram afetados 38 bovinos, verificando-se letalidade de 100 por cento. Amostras de conteúdo intestinal, ruminal e fígado de sete animais necropsiados e amostras de água dos bebedouros e do milho utilizado na alimentação foram submetidas ao bioensaio e à soroneutralização para a detecção de toxina botulínica. Toxinas dos tipos C e D foram detectadas nas amostras de conteúdo intestinal, ruminal e milho. O surto descrito mostra que o milho estocado em condições inadequadas pode ser um fator de risco para a ocorrência da doença.

An outbreak of bovine botulism in a dairy herd caused by ingestion of contaminated maize, in southern Minas Gerais, Brazil is described. The herd was composed by 148 lactating cows of high milk production fed with diet based on maize ensilage and concentrate in a free stall system. Thirty eight cows were affected, with 100 percent of fatality rate. Samples from intestine, rumen and liver of necropsied cattle and drinking water and maize were submitted to the mouse bioassay and soroneutralization tests for detection of Clostridium botulinum toxins. Types C and D toxins were detected in samples from intestinal and rumen contents and maize. The reporter of an outbreak of botulism in cattle associated with an unusual source of toxin, shows that stocked maize in inadequate conditions is a factor of risk for the occurrence of the botulism in dairy cattle.

Digestibilidade do bagaço de cana-de-açúcar tratado com hidróxido de sódio em dietas para coelhos em crescimento / Digestibility of sugar cane bagasse after a NaOH treatment in growing rabbit diets

Avaliou-se o bagaço de cana-de-açúcar não tratado (BN) e tratado (BT) com 2, 4 e 6 por cento de hidróxido de sódio (NaOH) na dieta para coelhos em crescimento. Os coeficientes de digestibilidade (CD) dos nutrientes do BN e BT foram determinados em delineamento inteiramente casualizado, com cinco tratamentos (ração básica e rações com 40 por cento de bagaço com 0, 2, 4 e 6 por cento de NaOH) e quatro repetições. Para obtenção dos valores de CD apenas do bagaço, e não da dieta total, adotou-se o método de substituição isométrica da dieta basal proposto por Matterson et al. (1965). A adição de NaOH ao bagaço não melhorou significativamente (P>0,05) os CD da matéria seca, proteína bruta, fibra em detergente neutro, fibra bruta e energia bruta e piorou significativamente (P=0,0023) o CD da fibra em detergente ácido (y = 20,042 - 2,7615x, r² = 0,984). Concluiu-se que o tratamento do bagaço de cana-de-açúcar com NaOH não trouxe vantagens práticas sobre os valores de CD que justificassem o seu uso, já que a adoção dessa técnica demanda aumento de mão-de-obra e do custo da alimentação.

The NaOH treated sugar cane bagasse (BT) (2, 4 e 6 percent) and untreated cane bagasse (BN) was evaluated as rabbit diet ingredients. The digestion coefficients (CD) were determined in a completely randomized design, with five treatments (basic diet) and 40 percent bagasse diets (0, 2, 4 e 6 percent NaOH) and four replications, using substitution methodology (Matterson et al., 1965). The nutritive values of bagasse (DM, CP, NDF, CF and GE) were not significantly (P>0,05) affected by NaOH treatment, whereas AFD was significantly (P = 0,0023) linearly decreased by the chemical treatment (y = 20,042 - 2,7615x , r² = 0,984). It was concluded that the treatment was not effective to improving the CD of sugar cane bagasse, being the practice not justifiable.

Effect of the feeding pattern on rumen wall morphology of cows and sheep

Nutritional manipulation of the rumen wall volatile fatty acid absorption capacity can be a strategy to control ruminal acidosis in dairy cows. Aiming to induce morphological rumen wall variation through diet and to establish efficient papillae morphological markers 2 experiments were performed. In experiment 1, seven rumen-cannulated cows were fed with concentrate 1 or 4 times a day for 19 days followed by fasting for 72 hours. Ruminal papillae were collected on days, 0, 4, 12 and 19 of the treatment period, and 24, 48 and 72 hours after onset of fasting which was able to induce papilar involution. Lower concentrate feeding frequency was associated to insulin increasing over time (P=0,02) and higher (P=0,03) mitotic index (MI), but it did not affect other morphological parameters. In experiment 2, two non-simultaneous trials with 3 rumen-cannulated ovines in each, were conducted and animals were fasted abruptly for 72 hours after feeding. Papillae were collected at the end of the feeding period and at the end of the 72 hour fasting period. MI was higher in the feeding period than the in fasting period (P<0,01), but other morphological parameters were not able to respond to nutritional variation. Among the morphologic markers studied MI seems to be the best variable for evaluation of the rumen epithelium morphologic response to feeding plans. Frequency of concentrate feeding may be used to regulate rumen papillae morphology.

A manipulação nutricional da capacidade de absorção de ácidos graxos voláteis pela parede do rúmen pode ser uma estratégia para controlar acidose em vacas leiteiras. Objetivando induzir variação morfológica da parede do rúmen através da dieta e estabelecer marcadores morfológicos eficientes para epitélio ruminal, dois experimentos foram relizados. No experimento um, sete vacas com cânula ruminal foram alimentadas com concentrado uma ou quatro vezes ao dia por 19 dias seguidos por 72 horas de jejum. Papilas ruminais foram coletadas nos dias zero, quatro, 12 e 19 do período de tratamento e 24, 48 e 72 horas após o início do período de jejum. Baixa freqüência de alimentação concentrada foi associada a um aumento de insulina plasmática através do tempo (P=0,02) e a um maior (P=0,03) índice mitótico (IM), mas não afetou outros parâmetros morfológicos. No experimento dois, foram realizados dois ensaios não-simultâneos com três ovinos canulados no rúmen, os quais foram submetidos abruptamente a 72 horas de jejum. Papilas ruminais foram coletadas no final do período de alimentação e no final do jejum. O IM foi mais alto no período de alimentação do que no período de jejum (P<0,01), mas outros parâmetros morfológicos não foram capazes de responder à variação nutricional. Entres os marcadores morfológicos estudados o IM parece ser a melhor variável para avaliação da resposta morfológica do epitélio ao plano alimentar. A freqüência de alimentação concentrada pode ser usada para regular a morfologia das papilas ruminais.

Effect of the feeding pattern on rumen wall morphology of cows and sheep / Efeito do padrão alimentar sobre a morfologia da parede ruminal devacas e carneiros

Nutritional manipulation of the rumen wall volatile fatty acid absorption capacity can be a strategy to control ruminal acidosis in dairy cows. Aiming to induce morphological rumen wall variation through diet and to establish efficient papillae morphological markers 2 experiments were performed. In experiment 1, seven rumen-cannulated cows were fed with concentrate 1 or 4 times a day for 19 days followed by fasting for 72 hours. Ruminal papillae were collected on days, 0, 4, 12 and 19 of the treatment period, and 24, 48 and 72 hours after onset of fasting which was able to induce papilar involution. Lower concentrate feeding frequency was associated to insulin increasing over time (P=0,02) and higher (P=0,03) mitotic index (MI), but it did not affect other morphological parameters. In experiment 2, two non-simultaneous trials with 3 rumen-cannulated ovines in each, were conducted and animals were fasted abruptly for 72 hours after feeding. Papillae were collected at the end of the feeding period and at the end of the 72 hour fasting period. MI was higher in the feeding period than the in fasting period (P<0,01), but other morphological parameters were not able to respond to nutritional variation. Among the morphologic markers studied MI seems to be the best variable for evaluation of the rumen epithelium morphologic response to feeding plans. Frequency of concentrate feeding may be used to regulate rumen papillae morphology.(AU)

A manipulação nutricional da capacidade de absorção de ácidos graxos voláteis pela parede do rúmen pode ser uma estratégia para controlar acidose em vacas leiteiras. Objetivando induzir variação morfológica da parede do rúmen através da dieta e estabelecer marcadores morfológicos eficientes para epitélio ruminal, dois experimentos foram relizados. No experimento um, sete vacas com cânula ruminal foram alimentadas com concentrado uma ou quatro vezes ao dia por 19 dias seguidos por 72 horas de jejum. Papilas ruminais foram coletadas nos dias zero, quatro, 12 e 19 do período de tratamento e 24, 48 e 72 horas após o início do período de jejum. Baixa freqüência de alimentação concentrada foi associada a um aumento de insulina plasmática através do tempo (P=0,02) e a um maior (P=0,03) índice mitótico (IM), mas não afetou outros parâmetros morfológicos. No experimento dois, foram realizados dois ensaios não-simultâneos com três ovinos canulados no rúmen, os quais foram submetidos abruptamente a 72 horas de jejum. Papilas ruminais foram coletadas no final do período de alimentação e no final do jejum. O IM foi mais alto no período de alimentação do que no período de jejum (P<0,01), mas outros parâmetros morfológicos não foram capazes de responder à variação nutricional. Entres os marcadores morfológicos estudados o IM parece ser a melhor variável para avaliação da resposta morfológica do epitélio ao plano alimentar. A freqüência de alimentação concentrada pode ser usada para regular a morfologia das papilas ruminais.(AU)