Resumo O objetivo deste trabalho foi determinar como os diferentes tipos de andamento afetam as respostas fisiológicas e termográficas de cavalos Pantaneiro (Equus ferus caballus) submetidos a condições ambientais com alta temperatura. Dez cavalos foram avaliados em delineamento experimental de quadrado latino 5x5 duplo, com cinco andamentos: passo, trote, trote estendido, galope e galope estendido. As seguintes medidas fisiológicas foram determinadas logo após os exercícios: taxas cardíaca e respiratória, teor de lactato sanguíneo e temperatura retal. As imagens termográficas foram avaliadas por meio de câmera de infravermelho. O passo, o trote e o trote estendido foram os andamentos mais adequados para os cavalos Pantaneiros manterem a termorregulação dentro das normas fisiológicas em condições de alta temperatura do ar. As temperaturas obtidas nas regiões da área do olho e da axila mostram maior capacidade preditiva para os parâmetros fisiológicos.

Abstract The objective of this work was to determine how different types of gait affect the physiological and thermographic responses of Pantaneiro horses (Equus ferus caballus) subjected to field conditions under high environmental temperatures. Ten horses were evaluated in a double 5x5 Latin square experimental design, with five gait types: walk, trot, extended trot, gallop, and extended gallop. The following physiological measures were determined immediately after exercise: heart and respiratory rates, blood lactate content, and rectal temperature. Body surface temperatures were evaluated using an infrared camera. The walk, trot, and extended trot were the most adequate gaits for Pantaneiro horses to maintain thermoregulation within the physiological norms under conditions with a high air temperature. The temperatures obtained in the eye and elbow regions show the best predictive capacity for physiological parameters.

ABSTRACT The objective of this work was to estimate genetic parameters and evaluate genetic trends over 26 years for morphometric traits in Mangalarga Marchador horses. Twelve morphometric traits were evaluated (withers and croup heights; length of head, body, shoulder, croup, neck, back, and loins; width of head and croup, and cannon bone and thorax perimeters). These traits were evaluated in 38,341 animals born between 1987 and 2012 and with a relationship matrix of 77,719 animals. Gibbs sampler was used to obtain samples of the posterior distributions of genetic parameters under animal models. Genetic trends were estimated by regression of estimated breeding values in function of birth year. The heritabilities of all traits were moderate to high and ranged from 0.27 to 0.48. However, the additive genetic coefficients of variation were low, ranging from 1.23 to 3.82%. The genetic trends of all the studied traits were significant, but of low magnitude. Negative genetic trend was observed for body length, while positive genetic trends were estimated for the other 11 traits. Although additive genetic differences accounted for a significant part of the phenotypic differences, genetic gains in the population were limited by low phenotypic variability. Therefore, it is necessary to develop data collection strategies to increase phenotypic and genetic variability in the population, such as the inclusion of animals that do not meet breed standard, but which have parents registered in the breeders’ association, in the database.

RESUMO: A conformação pode estar diretamente relacionada a qualidade dos movimentos direcionando a seleção dos equinos por aptidão. Objetivou-se identificar quais medidas lineares explicam a variância total disponível nas marchas batida e picada em cavalos jovens da raça Mangalarga Marchador. As análises foram realizadas pela avaliação de 20 medidas lineares de 420 equinos campeões de exposições, separados por sexo (macho-M e fêmeas-F), tipo de marcha (batida-MB e picada-MP) e oito grupos etários. Utilizou-se análise de componentes principais (ACP) para identificar quais características eram mais importantes na determinação da variância das marchas, selecionando aquelas contidas em CP, cuja soma de autovalores foi capaz de explicar o percentual mínimo de 80% da variação total. O número de CP variou de acordo com as faixas etárias, sendo de 2 a 3 em M e F-MP, de 3 a 4 para M-MB e até 5 para F-MB, o que sugere menor variação em animais de MP, e maior em F-MB. Não houve padrão na quantidade de CP por classe etária demonstrando variações independentes entre categorias. A maior variância geral foi explicada pelo comprimento de canela posterior e perna. A grande variância no comprimento desses segmentos, independentemente de sexo, idade, tipo de marcha e o fato dos mesmos não serem mensurados cotidianamente, sugere que não ocorre somente a ausência de padronização, mas também há compensação de tamanho entre eles, visto que se avaliou apenas animais campeões da raça.

ABSTRACT: The conformation is directly related to the quality of the movements, and can direct the selection by equine aptitude. This study aimed to identify which are the morphometric measurements that explain the total variance available in the marcha batida and picada gaits of young Mangalarga Marchador horses. Analyses were performed by evaluating 20 linear measurements of 420 champion horses. Measures were separated by gender (male-M and female-F), type of marcha, (batida-MB e picada-MP) and divided into eight age groups. Principal component analysis (PCA) was used to identify which measurements were most important in determining marcha variance by selecting principal component (PC) which sum of eigenvalues was able to explain the minimum percentage of 80% of the total variation. The PC number varied randomly according to age groups, being 2 to 3 in both genders in MP, 3 to 4 for M-MB, and up to 5 for F-MB, suggesting lower overall variability in MP, and higher in F-MB. There was no defined pattern concerning the amount of PC per age group, demonstrating that each category may have independent variations. Although, some repetitions of variables occurred similarly in different ages, sexes, and marcha types, the responsibility for the highest occurrence of variation was the posterior cannon and gaskin length. The significant variance in the length of these segments, regardless of gender, age, and marcha, and the fact they are not measured daily suggested there is not only a lack of standardization of these segments, but there is also size compensation among them since the group evaluated is composed of breed champions.

Resumo: O objetivo deste trabalho foi avaliar o efeito da anemia infecciosa equina (AIE) no desempenho físico de equinos da região do Pantanal brasileiro. Foram avaliados 16 machos, divididos em dois grupos: 8 soronegativos (G1) e 8 soropositivos (G2) para AIE. Dois testes de esforço progressivo foram realizados, antes (T1) e após (T2) 42 dias de treinamento. Foram registrados frequência cardíaca, concentração de lactato, distância percorrida e níveis de hematócrito. Em ambos os testes, o G1 percorreu uma distância maior. No T2, o G2 apresentou menores níveis de hematócrito e menor velocidade obtida a diferentes concentrações de lactato e frequências cardíacas. O desempenho atlético dos equídeos avaliados é afetado pela anemia infecciosa equina.

Abstract: The objective of this work was to evaluate the effects of equine infectious anemia (EIA) on the physical performance of equines from the Brazilian Pantanal region. A total of 16 males were evaluated, divided into two groups: 8 seronegative (G1) and 8 seropositive (G2) for EIA. Two graded exercise tests were carried out before (T1) and after (T2) 42 days of training. Heart rate, lactate concentration, distance covered, and hematocrit level were recorded. In both tests, G1 covered a greater distance. In T2, G2 had lower hematocrit levels and lower speeds reached at different lactate concentrations and heart rates. The athletic performance of the evaluated equines is affected by equine infectious anemia.

ABSTRACT This study aimed to assess the physical performance of Pantaneiro horses with and without equine infectious anemia (EIA) under functional conditions of cattle management. The horses were subjected to a performance test and split into two groups according to a completely randomized design: animals were chosen from populations testing positive and negative for EIA. Performance was measured as a function of a data envelopment analysis (DEA) model considering four outputs and one unitary input. The output measures were the distance achieved in the performance test, hematocrit as a weighted average over the test duration, respiratory rate as weighted average over the test duration, and the level of lactic acid at the test termination. Weights for the hematocrit and the respiratory rate output variables were determined by means of factor analysis. The performance score was a weighted average of the output variables with the weights defined by the averages of the optimum individual multipliers in the DEA analysis. Contextual variables of interest were age, horse weight, room temperature, and corporal temperature. Only groups and room temperature were statistically significant effects, as indicated by a bootstrap analysis. The performance of group positive for EIA is significantly lower than that of the group negative for EIA and room temperature has a negative effect.

ABSTRACT This study aimed to verify whether the criterion of exhibition contests adopted for Campolina and Mangalarga Marchador breeds has been successful in recent years, i.e., if the subsequent generations have the morphology recommended by the standard of the breed allied with high-quality marcha, a four-beat ambling gait. The classifications achieved by each horse during national horse shows in morphology and gait contests underwent Spearman's correlation to verify the number of contests with a correlation between the classifications in the two judgments and those with no correlation. Next, the number of contests with or without such correlation underwent a frequency distribution test considering the variables breed, year, age, marcha category, and sex. Spearman's correlation coefficient (r) of contests with a correlation was also used as a parameter. A difference was observed among years of evaluation only for Mangalarga Marchador horses, with a greater number of contests with correlations between morphological and ambling gait performances between 1998 and 2004. On both breeds, the correlation was found in more contests among foals than adult horses. When Spearman's correlation coefficients were compared, Campolina contests exhibited a higher r than Mangalarga Marchador, 68.14 and 63.68%, respectively. Only Mangalarga Marchador males had higher r value than females, 67.27 and 59.73%, respectively. The contest criterion adopted by Campolina and Mangalarga Marchador associations to select superior individuals does not correlate, in subsequent generations, with the morphology recommended by the standard of the breeds with high-quality marcha progress in the same individuals.

ABSTRACT The objective of this study was to examine serum retinol and some mineral (zinc, iron, calcium, phosphorus, magnesium, and copper) levels in seven Mangalarga Marchador colts aged 329.48 days, reared on pasture in the city of Montes Claros, MG, Brazil, during the dry season. Equines were evaluated for four periods of 45 days during the total study period of five months. The foals had access to Panicum maximum cv. Tanzania pasture, while water and mineral salt lick were provided ad libitum. Blood samples were taken to determine serum retinol and levels of minerals, along with pasture samples to quantify beta-carotene in the grass. The results indicated that retinol levels varied (2.87 to 1.97 µg/dL) and remained below the standard levels. The levels of zinc, iron, calcium, and phosphorus did not vary significantly with average values of 36.79 µg/dL, 77.32 µg/dL, 10.33 mg/dL, and 9.99 mg/dL, respectively. However, zinc and calcium remained below standard concentrations of 60-120 µg/dL and 10.8-13.5 mg/dL, respectively, since the beginning of the study. On the other hand, copper and magnesium levels decreased over time (97.76 to 77.56 mg/dL and 2.86 to 2.21 µg/dL, respectively), but showed normal levels for horses during the research. Beta-carotene in grass showed a downward trend over time from 38.53 to 0.09 mg/kg of dry matter. The results also indicated a significant relationship between serum retinol and serum copper levels. Vitamin A supplementation is necessary whenever foals are fed pastures during the dry season.

RESUMO: A raça Mangalarga Marchador é responsável pelo maior rebanho de equinos do país e tem alcançado crescente expansão nacional e internacional. Apesar disso, é escassa a produção científica sobre a evolução dessa raça e não existem estudos sobre as transformações morfométricas que ocorreram ao longo de sua formação. Neste contexto, o presente estudo objetivou avaliar a evolução das medidas morfométricas da raça Mangalarga Marchador entre 1970 e 2010. Foram utilizadas informações arquivadas na Associação Brasileira dos Criadores do Cavalo Mangalarga Marchador de 23148 machos e 92980 fêmeas, em delineamento experimental inteiramente ao acaso. Os seis tratamentos foram constituídos pelos animais mensurados de 1970 a 1979, 1980 a 1989, 1990 a 1994, 1995 a 1999, 2000 a 2004 e 2005 a 2010, respectivamente. As medidas avaliadas foram: alturas na cernelha e garupa, comprimentos da cabeça, pescoço, dorso-lombo, garupa, espádua e corpo, larguras da cabeça e da garupa, além de perímetros torácico e da canela. Ao longo do período avaliado observou-se nos machos e fêmeas redução do perímetro torácico, dos comprimentos da cabeça, dorso-lombo, garupa e espádua e das larguras de cabeça e garupa. Nos machos houve também redução no comprimento do pescoço e aumento no perímetro da canela. Nas fêmeas verificou-se aumento no comprimento do corpo. Ao longo do tempo, a seleção da raça conferiu aos animais menor cabeça, maior estatura e menor comprimento do tronco. No entanto, houve redução de medidas importantes para sua funcionalidade, como o comprimento da espádua e do perímetro torácico.

ABSTRACT: The Mangalarga Marchador breed accounts for the largest horse herd in Brazil and has been experiencing national and international expansion. Nevertheless, there is little scientific production on the evolution of this breed and there are no studies on the morphometric transformations that took place during its formation. In this context, the present study aimed to assess the evolution in morphometric measures of the Mangalarga Marchador breed between 1970 and 2010. The research used information archived at the Brazilian Association of Mangalarga Marchador Breeders from 23,148 males and 92,980 females in a completely randomized experimental design. The six treatments consisted of the animals measured between 1970 and 1979, 1980 and 1989, 1990 and 1994, 1995 and 1999, 2000 and 2004, and 2005 and 2010, respectively. The measures assessed were: height at withers and croup, length of the head, neck, back, croup, shoulder, and body, width of the head and croup, thoracic circumference, and cannon circumference Over the period analyzed, males and females experienced a reduction in thoracic circumference, in the lengths of the head, back, croup, and shoulder, and in the widths of the head and croup. In the males, neck length and cannon circumference also decreased, while body length increased in females. Over time, breed selection led to smaller head, higher stature, and shorter trunk length. However, important measures for the breed's functionality, such as shoulder length and thoracic circumference, decreased.

The objective of this study was to assess the effects of supplementation with Saccharomyces cerevisiae on the performance of Mangalarga Marchador equines and to verify the effectiveness of the aerobic training protocol adopted. The study used 14 Mangalarga Marchador mares in a completely randomized split-plot design. The plots were made up of two treatments (groups Probiotic and Control) and the split plots comprised two maximal-effort physical tests applied both before and after the six weeks of training. The animals' spirometric parameters, heart rate, and plasma lactate levels were assessed. No difference was found between the Probiotic and Control groups in any of the parameters assessed. A difference was found in the physical tests for time-to-fatigue, aerobic and anaerobic thresholds, speed at which plasma lactate levels reached 2 and 4 mmol/L, speed at which the heart rate reached 200 bpm, and the lactate level at 30 min of the recovery period. Supplementation with Saccharomyces cerevisiae has no effect on physical conditioning of Mangalarga Marchador mares and the aerobic training protocol adopted increases the animals' aerobic and anaerobic capacity.

Objetivou-se comparar as medidas morfométricas do rebanho atual de fêmeas Mangalarga Marchador (MM) com os exemplares campeões. O delineamento experimental foi inteiramente ao acaso, sendo os tratamentos constituídos pelo rebanho atual de fêmeas da raça MM, representado por todas as éguas registradas entre 2000 e 2012 que tiveram suas medidas armazenadas no banco de dados do Serviço de Registro Genealógico da Associação Brasileira de Criadores do Cavalo Mangalarga Marchador, totalizando 51993 animais; e pelas campeãs da raça, representadas por 266 animais campeões. Foram avaliadas a altura na cernelha e na garupa, comprimento da cabeça, pescoço, espádua, dorsolombo, garupa e corpo, largura da cabeça e da garupa e perímetro torácico e da canela. As medidas lineares foram relacionadas ao comprimento da cabeça, de acordo com o Sistema Eclético de Proporções. Os resultados das 12 medidas lineares foram submetidos à análise de variância e as médias comparadas pelo teste de Fisher (p<0,05). Em relação ao rebanho atual de fêmeas MM, as éguas campeãs da raça apresentaram maior comprimento da cabeça, corpo, pescoço, dorso-lombo e garupa, altura na cernelha e na garupa, largura da garupa e perímetro torácico e da canela. Concluiu-se que embora apresentem maiores medidas lineares, as éguas campeãs MM são proporcionalmente semelhantes ao rebanho atual de fêmeas da raça.

The study aimed to compare the morphometric measures of the current herd Mangalarga Marchador (MM) female with champions breed, using as parameters the breed standard and the Eclectic System of Proportions for saddle horse. The experimental design was randomized, and the treatments were the current herd MM female, represented by all mares registered between 2000 and 2012 that had your measurements stored in the database service studbook of breed, totaling 51993 animals, and the champions breed, represented by 266 mares champions. Were evaluated measures of height at withers and at rump, length of the head, neck, dorse, rump, shoulder and body, width of head and of rump, thoracic perimeter and cannon perimeter. The mean linear measurements were related to the length of the head, according to Eclectic System of Proportions. The results were submitted to analysis of variance and the means were compared by Fisher's test (p<0.05). Regarding the current herd of females MM, the champions breed showed greater length of the head, body, neck, dorse and rump, height at withers and at rump, width of rump and thoracic and cannon perimeter. It was concluded that although larger, the champions Mangalarga Marchador mares are proportionally similar to the current herd.

A raça Mangalarga Marchador (MM), valorizada por apresentar como andamento a marcha, vem se destacando nas atividades funcionais, como as provas de marcha. Considerando a escassez de informações sobre a fisiologia esportiva dos equinos marchadores, a elaboração de protocolos de treinamento e de testes físicos torna-se fundamental e, nesse contexto, as concentrações dos gases e eletrólitos sanguíneos constituem informações adicionais para o monitoramento das alterações metabólicas induzidas pelo exercício. Objetivou-se avaliar as respostas hemogasométricas e a concentração sanguínea de eletrólitos de éguas MM, durante teste de esforço máximo em esteira, realizado antes e após o treinamento - ensaio 1 e entre um teste de esforço máximo em esteira e um teste de intensidade crescente a campo - ensaio 2. Foram avaliadas a concentração plasmática de lactato, o pH sanguíneo, as pressões sanguíneas de oxigênio e de dióxido de carbono, as concentrações sanguíneas dos íons bicarbonato, sódio (Na+), potássio (K+) e cálcio (Ca++). O delineamento foi em blocos ao acaso em esquema de parcelas subdivididas. No primeiro ensaio, as distâncias percorridas pelos equinos nos testes antes e após o treinamento resultaram em redução (p<0,05) do pH sanguíneo e na concentração de Ca++ e aumento (p<0,05) nas concentrações de K+ e Na+. No segundo ensaio, a influência do tipo de teste realizado e a temperatura ambiental resultaram em redução (p<0,05) do pH sanguíneo e aumento (p>0,05) nas concentrações de K+ e Ca++. Após o treinamento, éguas MM apresentam alterações mais intensas do pH e das concentrações dos eletrólitos.

The Mangalarga Marchador (MM) breed, valued for its marcha pace, has been excelling in functional activities such as marcha course. Considering the lack of information about sports physiology of the marcha horses, the development of training protocols and physical testing becomes essential and, in this context, the concentrations of blood gases and electrolytes provide additional information for the monitoring of metabolic changes induced by exercise. The goal of the study was to assess the hemogasometric responses and blood electrolyte concentration in MM mares during maximal effort treadmill tests carried out before and after training (trial 1) and between a maximal effort treadmill test and an incremental field test (trial 2). The trials assessed plasma lactate concentration, blood pH, oxygen and carbon dioxide blood pressures, and blood concentrations of the ions bicarbonate, sodium (Na+), potassium (K+), and calcium (Ca++). The study followed a randomized block in a split-plot design. In the first trial, the distances walked by the equines in the tests before and after training caused decrease (p<0.05) in pH and Ca++ concentration and increase in the concentrations of K+ and Na+. In the second trial, the influence of the type of test and the ambient temperature caused decrease (p<0.05) in pH and increase in the concentrations of K+ and Ca++. After training, MM mares had greater changes in pH and electrolyte concentrations.

O trabalho avaliou o efeito da suplementação com leveduras na dieta de equinos em treinamento, sobre a digestibilidade dos nutrientes e o desempenho metabólico dos animais. Doze equinos foram distribuídos em 2 grupos: Pr (equinos que receberam 20 g de probióticos diariamente) e Controle. A dieta foi composta de volumoso (haylage) e concentrado comercial e todos os equinos foram treinados durante 6 semanas. A digestibilidade dos nutrientes foi avaliada utilizando o indicador LIPE® (7 dias) e a coleta de fezes foi realizada durante cinco dias. Foi analisado MS, PB, DE, P, FDN, FDA, HCEL e lignina. Antes e após o treinamento, todos os cavalos foram submetidos a um teste incremental ergoespirométrico. Os equinos que receberam leveduras vivas apresentaram um aumento (p <0,05) de 4,1% na digestibilidade da HCEL. Após o treinamento, ambos os grupos apresentaram maior tolerância à fadiga, com um aumento na AT e no VO2max. O treinamento melhorou o desempenho dos animais, e a digestibilidade da hemicelulose e DE foi maior no grupo Pr, mas esses aumentos não melhoraram o desempenho desses animais.

This research analyses the yeast supplementation effect on the digestibility of nutrients and metabolic performance in training horses. Twelve horses were assigned into 2 groups: Pr (20 g of probiotics daily per horse) and control. The diet consisted of roughage (haylage) and commercial rations and all horses were trained for 6 weeks. LIPE® indicator was used during 7 days and feces collected for five days to determine nutrient digestibility. DM, CP, DE, P, NDF, ADF, HCEL and lignin were determined. All horses were subjected to incremental ergospirometry test before and at the end of training. Horses that received live yeast showed an increase (p<0.05) of 4.1% in the digestibility of HCEL. After training, both horse groups presented higher tolerance to fatigue, with an increase in AT and VO2max. The training improved animal performance, hemicellulose digestibility and DE was higher in Pr, but these increases did not improve the performance of these animals.

This study was carried out to evaluate intake, nutrient digestibility and body weight gain of foals on diets of concentrate and legume hay. Treatments were: lucerne hay (Medicago sativa), Campo Grande stylo hay (20% Stylosanthes macrocephala and 80% Stylosanthes capitata) and Mineirão stylo hay (Stylosanthes guianensis cv. Mineirão). Fifteen weaned foals at 160 Kg body weight (BW) were used. The experiment was entirely randomized with three treatments and five replicates. Dry matter intake was estimated at 30 g of dry matter (DM)/kg BW and was comprised of 40% concentrate meal and 60% hay. Fecal production and nutrient digestibility were calculated by the LIPE® marker methodology. There was no difference between Lucerne hay and Campo Grande stylo hay intake, but intake of Mineirão stylo hay was lower than that of Lucerne hay. Body weight gain and nutrient digestibility coefficients were similar for foals fed different diets. Intake was similar for Campo Grande and Lucerne hay, and led to similar body weight gain in diets with concentrate. Mineirão stylo hay, at 137 days of growth, was not palatable for the foals.

Foi comparado o julgamento do escore de condição corporal (ECC) com a espessura de gordura subcutânea (EGS) e sua relação com a eficiência reprodutiva de éguas Mangalarga Marchador doadoras de embrião. O experimento foi conduzido com 56 éguas doadoras entre os meses de agosto/08 e abril/09. O ECC foi maior em éguas mais velhas e aumentou com os dias de permanência no experimento. Houve correlação positiva entre peso e tempo de experimento. O peso não foi associado à idade, porém aumentou ao longo do experimento. A EGS na região da cauda e entre a 12ª e 13ª costelas aumentou com a idade e diminuiu com os dias de permanência no experimento. Houve correlação positiva entre EGS e ECC para a cauda e costela. O diâmetro do folículo dominante aumentou ao longo do ciclo estral, e foi menor em éguas com ECC abaixo de 6,5. O diâmetro folicular não foi influenciado pela idade. O diâmetro médio do folículo ovulatório foi 38,43 ± 3,09 mm. A recuperação embrionária não foi afetada pela idade ou ECC, mas foi menor (41%) eméguas que ovularam folículos menores que 40 mm quando comparados às que ovularam folículos maiores que 40 mm (59%). A idade da doadora não foi associada à taxa de gestação dos embriões nas receptoras. A gordura corporal afetou a eficiência reprodutiva das éguas, além disso, a ultrassonografia parece ser essencial para a avaliação precisa e correta do escore de condição corporal.

Body condition scoring (BCS) was compared to an ultrasound subcutaneous fat thickness (SFT) determination in relation to the reproductive efficiency of Mangalarga Marchador embryo donor mares. Fifty six barren mares were studied throughout the 2008/2009 breeding season (August through April) and the experiment was designed in a completely randomized scheme. BCS was higher in older mares and increased with time in the experiment, and there was a positive interaction between weight and time. Weight was not associated with age, but increased throughout the experiment. Tail and rib BCS increased with age, and decreased with time. There was a positive correlation between BCS and tail and rib SFT. The diameter of the dominant follicle increased during the estrous cycle and was smaller for mares with BCS below 6.5. Age did not influence the dominant follicle diameter. The mean ovulatory follicle diameter was 38.43 ± 3.09. Embryo recovery was not affected by age or BCS but was lower (41%, P=0.003) in mares that ovulated follicles smaller than 40mm compared to mares ovulating follicles greater than 40mm (59%). Donor age was not associated with recipient pregnancy rates. Body fat affected the reproductive efficiency in mares, and seems that ultra-sonography may be essential for correct and reliable body condition scoring.

O trabalho foi realizado visando avaliar a influência da suplementação de probióticos ou fitase sobre o consumo diário de matéria seca (CMS), o ganho de peso diário (GPD) e a conversão alimentar (CA) de 24 potros da raça Mangalarga Marchador (16 machos e 8 fêmeas), com 241,6 ± 23,2 dias de idade e 216,7 ± 27,8 kg de peso vivo (PV). O experimento teve duração de 28 dias: os 23 iniciais para adaptação à dieta e ao manejo e os cinco finais para coleta de fezes. A dieta foi composta por pastagem de Cynodon e concentrado comercial (1,2 kg/100 kg PV), além de água e sal mineral à vontade. Os tratamentos foram: dieta basal (controle); dieta basal + 5 g/dia de leveduras vivas (10(9) UFC/g de Saccharomyces cerevisiae); dieta basal + 2 g/dia de bactérias (10(8) UFC/g de B. bifidum, E. faecium, L. acidophilus, L. plantarum) e leveduras vivas (10(5) UFC/g de S. cerevisiae) e dieta basal + fitase (1.250 FTU/dia). Para estimativa do consumo de matéria seca, foram utilizados o indicador externo LIPE® e a técnica de digestibilidade in situ. O delineamento foi inteiramente casualizado, em fatorial 4 × 2, e as médias comparadas pelo teste Student, considerando o efeito da covariável PV inicial para porcentagens de CMS por PV. O consumo de matéria seca total dos grupos variou de 2,4 a 2,8% PV, de modo que os animais sob suplementação com bactérias e leveduras vivas apresentaram menor CMS total e de volumoso. Todos os animais tiveram GPD médio de 0,33 kg/dia e o grupo sob suplementação com bactérias e leveduras vivas teve conversão alimentar do volumoso 32,42 a 43,83% menor que a observada no grupo controle e naquele sob suplementação com fitase. A fitase, na dosagem de 205 FTU/kg de MS da dieta basal, não influenciou os parâmetros avaliados. O probiótico composto por bactérias e leveduras vivas melhorou a eficiência alimentar do volumoso e pode ser utilizado como estratégia nutricional para manutenção da condição corporal de potros durante o período seco.

The objective was to assess the effect of probiotic or phytase supplementation on dry matter intake (DMI), average daily gain (ADG) and feed conversion (FC) in 24 Mangalarga Marchador foals (16 males, 8 females), with 241.6 ± 23.2 days of age, and 216.7 ± 27.8 kg of body weight (BW). The study lasted 28 days, the first 23 days for diet and handling adaptation, and the last five days for feces collection. The basal diet consisted of Cynodon pasture and pelleted concentrate (1.2 kg/100 kg BW), as well as water and mineral salt ad libitum. Treatments groups were assigned as follows: basal diet (control); basal diet + 5 g/day of live yeast culture (10(9) CFU/g of S. cerevisiae); basal diet + 2 g/day of live bacteria (10(8) CFU/g of B. bifidum, E. faecium, L. acidophilus, L. plantarum) and yeast culture (10(5) CFU/g of S. cerevisiae); and basal diet + 1250 FTU/day of phytase. Pasture DMI was estimated with an external marker (LIPE™) associated with cecal in situ digestibility of dry matter. All foals were randomized, by replicated, using a 4 × 2 factorial, and results were compared using Student t-test, taking into consideration the effect of initial BW as covariate for the percentage DMI per BW. Among foals, DMI varied from 2.4 to 2.8% BW, with foals supplemented with live bacteria and yeast having lower DMI (total diet and forage). All animals had an ADG of 0.33 kg/day, and foals supplemented with live bacteria and yeast had FC 32.42 to 43.83% lower than foals supplemented with phytase or fed only basal diet. The phytase dose of 205 FTU/kg DM in the basal diet had no effects. Probiotic composed of live bacteria and yeast culture improved feed efficiency of forage and can be used as a nutritional strategy to maintain body condition in foals during the dry season.