ABSTRACT The objective of this study was to evaluate, through principal component analysis, the effect of different feedlot structures on climatic conditions, nutrient intake, and performance of Nellore bulls during the feeding period in the semi-arid region. Data from 225 non-castrated Nellore bulls with initial mean body weight (BW) of 294 ± 19 kg and age of 24 months were used. This was done in a completely randomized design with three feedlot structures (no shading, natural shade, and artificial shade with 50% light interception), resulting in 75 repetitions (each animal serving as an experimental unit). The feeding period for the animals in the feedlot was 107 days. The first two components explained 99.65 (no shade), 97.32 (artificial shade), and 99.89 (natural shade) of total data variation. The variables, namely the black globe temperature index (0.88), radiant heat load (0.96, 0.99, 0.76), black globe temperature (0.96), and hot carcass weight (0.64) exerted the greatest influence on the feedlot structures. Climatic and intake variables were identified as having the most significant impact on feedlot structures. Artificial shade with 50% light interception shade cloth positively contributes to the hot carcass weight of feedlot Nellore cattle. evaluate analysis conditions semiarid semi arid region 22 noncastrated non castrated BW (BW 29 1 2 used no shading 50 interception, , interception) 7 each unit. unit . unit) 10 days 9965 99 65 99.6 9732 97 32 97.3 9989 89 99.8 variation 0.88, 088 0.88 0 88 (0.88) 0.96, 096 96 (0.96 099 0.99 0.76, 076 0.76 76 0.76) 0.96 (0.96) 0.64 064 64 (0.64 cattle 5 996 9 6 99. 973 3 97. 998 8 08 0.8 (0.88 09 (0.9 0.9 07 0.7 0.6 06 (0.6 0. (0.8 (0. (0 (

ABSTRACT The objective of this study was to evaluate the effects of wilting times and application of an enzymatic-bacterial inoculant on the fermentative profile and nutritional characteristics of BRS capiaçu grass silage in a semi-arid region. Four wilting times treatments (control, 6, 24, and 30 h), with or without the addition of an enzymatic-bacterial inoculant, were analyzed as a split-plot completely randomized design with eight replications. Parameters of the rumen degradability test were analyzed using a split-plot completely randomized block design with four replications. There was no interaction between wilting times and inoculant application on pH, ammoniacal nitrogen (NH3-N), and aerobic stability of BRS capiaçu silage. Aerobic stability was reduced by 1.2 h for every 1-h increase in wilting time. Inoculant application reduced the pH values by 2.59% and extended the aerobic stability of the silage by 19 h. There was a significant interaction of wilting times and inoculant application on the levels of malic, succinic, lactic, and acetic acids. Inoculant application increased the contents of dry matter, ash, crude protein, insoluble neutral detergent fiber, and total carbohydrates by 3.63, 6.13, 7.73, 6.39, and 9.97% compared with non-inoculated silages, respectively. Wilting times for up to 30 h and application of enzymatic-bacterial inoculant improves the fermentative profile and chemical composition and reduces dry matter losses of silage of BRS capiaçu grass harvested at 100 days of regrowth.

ABSTRACT The objective was to evaluate the effects of maturity at harvest and row spacing on fermentative profile, aerobic stability, and nutritional value of biomass sorghum (BRS 716) silage. The experiment was conducted using a split-plot completely randomized block design with three row spacings (45, 70, and 90 cm) and four maturities at harvest (70, 100, 130, and 160 days) and eight replications. Polyvinyl chloride silos of known weight measuring 50 cm length and 10 cm diameter were used for silage production. Dry matter and total carbohydrate contents of the silage increased linearly, whereas crude protein and ash decreased linearly with maturity at harvest. Row spacing did not influence pH, ammoniacal nitrogen (N-NH3), gas and effluent losses, and dry matter recovery of silage. The concentrations of malic, succinic, and acetic acids and ethanol responded quadratically to maturity at harvest. The levels of neutral detergent fiber, lignin, and indigestible neutral detergent fiber increased linearly with maturity at harvest. Ruminal degradation kinetics of dry matter of biomass sorghum silage was not influenced by row spacing. BRS 716 biomass sorghum should be planted at 70-cm row spacing and harvested at 160 days for silage production based on fermentative profile, dry matter losses, and nutritional characteristics.

ABSTRACT The objective was to group and characterize Zebu cattle carcasses according to sex. Data from 15,002 carcasses of cattle raised in the semiarid region of the state of Minas Gerais, Brazil, were used. The carcass characteristics analyzed were weight, conformation, subcutaneous fat, number of permanent incisor teeth (PIT), and sex (uncastrated males, castrated males, females (up to six PIT), and cows (eight PIT)). Cluster analysis was applied to establish the relationship between sex and carcass characteristics. Four clusters were identified according to sex, and 60% of the total variance in the data set is explained by the clusters. Uncastrated males appear together in a single group (Cluster 1), which demonstrates homogeneity in their carcass characteristics. The heaviest group was Cluster 1. The castrated males appear in three groups, some of them (33.58%) grouped with the majority of cows (92.85%), which indicates that these carcasses did not achieve the quality required by the industry. Another part of the castrated males (41.84%) presented characteristics required by the industry. The females appear in all clusters. Except for uncastrated males and cows, the effect of sex (castrated males and females) on the carcass characteristics of Zebu cattle from the semiarid region of the Minas Gerais does not assure similar characteristics. Therefore, the improvement of carcass quality, using castration as the central grading criterion, should be reviewed not to overemphasize this item.

RESUMO O conhecimento da prevalência da cisticercose bovina é importante para a implementação de programas de controle. Objetivou-se avaliar a prevalência e a distribuição geográfica de cisticercose bovina no Norte de Minas Gerais. Para isso, avaliou-se 14556 bovinos durante a inspeção federal post mortem provenientes de 27 municípios de cinco microrregiões: Janaúba, Montes Claros, Januária, Pirapora e Bocaiúva. A prevalência de Cysticercus bovis foi de 1,03% e está distribuída geograficamente em todas as microrregiões avaliadas do Norte de Minas Gerais avaliadas. Todos os municípios com número amostral de bovinos abatidos acima de 543 apresentaram animais positivos para cisticercose. As microrregiões de Bocaiúva, Montes Claros, Janaúba, Januária e Pirapora apresentaram prevalência de cisticercose de 2,11%, 1,17%, 1,01%, 0,90% e 0,56%, respectivamente. As microrregiões de Montes Claros e Januária apresentaram maior chance de se encontrar bovinos positivos para cisticercose. Como há casos positivos de cisticercose em todas as microrregiões avaliadas, há risco a saúde dos seres humanos.

ABSTRACT The knowledge of the prevalence of bovine cysticercosis is important for the implementation of control programs. The objective was to evaluate the prevalence and geographical distribution of bovine cysticercosis in Northern Minas Gerais. For that, 14,556 cattle were evaluated during the federal post-mortem inspection in 27 municipalities of five microregions: Janaúba, Montes Claros, Januária, Pirapora and Bocaiúva. The prevalence of Cysticercus bovis was 1.03% with distribution in all microregions evaluated of the northern Minas Gerais. All municipalities with a sampling number of cattle slaughtered above 543 showed positive animals for cysticercosis. The microregions of Bocaiúva, Montes Claros, Janaúba, Januária and Pirapora presented a prevalence of cysticercosis at 2.11%, 1.17%, 1.01%, 0.90% and 0.56%, respectively. The microregions of Montes Claros and Januária presented a greater chance of finding positive cattle for cysticercosis. As there are positive cases of cysticercosis in all microregions evaluated, there is a risk to human health.

RESUMO Objetivou-se determinar o fator de disponibilidade hídrica no solo que resultasse ao máximo desempenho agronômico do sorgo forrageiro irrigado, sem alterar sua composição químico-bromatológica. Para isso, utilizou-se uma área experimental do Campus Janaúba da Universidade Estadual de Montes Claros, MG, Brasil, sobre um Neossolo Flúvico Psamítico com capacidade total de armazenamento de água de 59 mm nos primeiros 0,3 m de profundidade. O experimento consistiu de 5 fatores de disponibilidade hídrica do solo (f0,2 = 0,20; f0,35 = 0,35; f0,5 = 0,50; f0,65 = 0,65 e f0,8 = 0,80) e dois híbridos simples de sorgo forrageiro (Volumax® e BRS 655), arranjados no esquema de parcelas subdivididas, com os híbridos nas subparcelas, no delineamento em blocos casualizados, com quatro repetições. A partir da diferenciação, quinzenalmente foram avaliados a altura de planta, diâmetro de colo, diâmetro transversal de planta, número de folhas por planta, índice de área foliar, teor relativo de clorofila, diâmetro de caule, comprimento de panícula, produção de matéria seca, eficiência de uso da água, proteína bruta, cinzas, fibra em detergente ácido, fibra em detergente neutro e lignina. O fator f entre 0,20 e 0,35 promove maior produção de matéria seca e altura de plantas nos dois híbridos de sorgo. O híbrido Volumax® apresentou melhores teores de proteína bruta e fibra em detergente ácido. Os fatores f testados não alteraram a composição químico-bromatológica dos híbridos.

ABSTRACT The objective of this work was to determine the factors of soil water availability (FSWA) that result in the highest agronomic performance of irrigated forage sorghum, with no changes in the plants' chemical-bromatological composition. The experiment was conducted at the Montes Claros State University, Janaúba campus, MG, Brazil, in a Typic Quartzipsamment (Neossolo Flúvico Psamítico - Embrapa) with 59 mm of soil water storage capacity in the 0.0-0.3 m layer, under drip irrigation. A randomized block design with four replications and a split-plot arrangement was used, consisting of five FSWA (f0.2 = 0.20; f0.35 = 0.35; f0.5 = 0.50; f0.65 = 0.65, and f0.8 = 0.80) in the plots and two simple forage sorghum hybrids (Volumax® and BRS-655) in the split-plots. The evaluations were based on fortnightly measurements of plant height, plant transversal diameter, number of leaves per plant, leaf area index, relative chlorophyll content, stem diameter, panicle length, dry matter yield, water use efficiency, crude protein, mineral matter, acid detergent fiber, neutral detergent fiber, and lignin. The FSWA of 0.20 and 0.35 increased dry matter yield and plant height of the two evaluated sorghum hybrids. The Volumax hybrid presented more crude protein content and acid detergent fiber. The evaluated FSWA did not change the chemical-bromatological composition of the sorghum hybrids.

Resumo: O objetivo deste trabalho foi avaliar a composição química e o perfil de ácidos graxos do leite de vacas F1 Holandês/Zebu, em diferentes períodos de lactação, ao receber diferentes níveis de fornecimento da dieta em percentagem de peso corporal. Foram utilizadas 60 vacas, com cinco níveis de oferta da dieta e três períodos de lactação. Os níveis de oferta não influenciaram a produção de leite corrigida a 3,5% de gordura (12,25 kg por dia). Também não houve efeito dos níveis de oferta, nos diferentes períodos de lactação, sobre os teores de gordura (3,34%), proteína (3,41%), lactose (4,60%), sólidos totais (12,0%), extrato seco desengordurado (8,80%) e nitrogênio urético (14,5 mg dL-1), nem sobre a contagem de células somáticas (89,98 mL-1). À medida que os níveis de oferta foram reduzidos, o somatório dos ácidos graxos saturados do leite diminuiu em até 9,15% e o dos monoinsaturados aumentou em até 25,28%. A restrição alimentar de vacas F1 Holandês/Zebu não altera a composição química do leite, mas melhora a qualidade da sua gordura, ao reduzir os teores de ácidos graxos saturados, aumentar os dos ácidos graxos monoinsaturados e dos ácidos graxos desejáveis em até 54%, e elevar a relação dos ácidos graxos hipo e hipercolesterolêmicos em até 168,97%.

Abstract: The objective of this work was to evaluate the chemical composition and fatty acid profile of milk from F1 Holstein/Zebu cows in different lactation periods, when receiving different levels of dietary supply in percentage of body weight. Sixty cows were evaluated, with five levels of dietary supply and three lactation periods. The levels of dietary supply had no effect on the production of milk corrected to 3.5% fat (12.25 kg per day). There was also no effect of dietary supply levels, in the different lactation periods, on contents of fat (3.34%), protein (3.41%), lactose (4.60%), total solids (12.0%), defatted dry extract (8.80%), and urinary nitrogen (14.5 mg dL-1), nor on somatic cell count (89.98 mL-1). As the dietary supply level was reduced, the sum of saturated fatty acids in milk was decreased in up to 9.15% and that of monounsaturated fatty acids was increased in up to 25.28%. Feed restriction does not alter the chemical composition of milk, but improves its quality of fat by reducing saturated fatty acid content, increasing the concentration of monounsaturated and desirable fatty acids in up to 54%, and increasing the hypo- and hypercholesterolemic fatty acid ratio in up to 168.97%.

ABSTRACT The objective of this study was to evaluate the effect of quantitative feed restriction level on nutrient intake and digestibility, nitrogen balance, efficiency and feeding behavior, and productive performance of F1 Holstein × Zebu cows in late lactation. Sixty F1 Holstein × Zebu cows were used at the stage of late lactation (183.0±17.5 days of lactation) and with initial body weight (BW) of 499±30 kg. The experimental arrangement adopted was the completely randomized design, with five feed restriction levels (3.39, 2.75, 2.50, 2.25, and 2.00% of BW) and twelve cows as replicates for each treatment. The roughage:concentrate ratio was of 75:25 in the total dry matter of the diet. The restriction of dietary supply from 3.39 to 2.0% of BW linearly reduced dry matter intake by 51.74%. The restriction in diet supply linearly increased dry matter digestibility in 13.76%. For each 1% BW restriction in the diet supply for the animals, there was a linear reduction of 3 h in feeding time. Restriction in diet supply of crossbred cows from 3.39 to 2.0% of BW reduced milk production by 24.84%. For each 1% restriction on supply, 2.17 L of milk were not produced. Milk production corrected to 3.5% fat was not altered with the feed restriction. Final BW decreased 41 kg for each percentage unit of diet restriction. Feed efficiency increased 28.72% with feed restriction. For F1 Holstein × Zebu cows in the late lactation, the restriction of dietary supply up to 2.0% of body weight decreases nutrient intake, nitrogen balance, rumination time, and milk production; however, it improves nutrient digestibility and feed efficiency of the animals.

Resumo: O objetivo deste trabalho foi avaliar a viabilidade de bactérias probióticas em bioiogurte adicionado de mel de abelhas africanizadas e Jataí, em diferentes concentrações. Para a elaboração do leite fermentado, utilizou-se leite em pó reconstituído e fermento lácteo. O bioiogurte foi avaliado com 0, 7, 14, 21, 28 e 35 dias de armazenamento. Foram realizadas análises de pH, acidez titulável e contagem seletiva dos microrganismos Lactobacillus acidophilus LA-5 e Bifidobacterium BB-12. As contagens foram realizadas, respectivamente, em ágar MRS, em aerobiose, e ágar MRS-LP, em anaerobiose, com placas incubadas a 37ºC por 72 horas. Os tratamentos foram arranjados em delineamento inteiramente casualizado, com parcelas subdivididas e cinco tratamentos: sem mel; 5 e 10% de mel de abelha africanizada; e 5 e 10% de mel de abelha Jataí. Os tempos de estocagem foram avaliados nas subparcelas. O bioiogurte apresentou contagens de bactérias láticas de 107 UFC g-1, em todos os tratamentos. As culturas probióticas mantiveram-se viáveis por 35 dias sob refrigeração (2-4°C). Houve efeito da interação entre os fatores de variação sobre a concentração dos probióticos no bioiogurte. Os méis têm efeito favorável sobre a contagem de células dos microrganismos avaliados.

Abstract: The objective of this work was to evaluate the viability of probiotic bacteria in bioyogurt with the addition of honey from Africanized and Jataí bees, in different concentrations. To prepare the fermented milk, reconstituted powdered milk and lactic acid starter culture were used. The bioyogurt was evaluated at 0, 7, 14, 21, 28, and 35 days of storage. Analyzes of pH, titratable acidity, and selective count of the Lactobacillus acidophilus LA-5 and Bifidobacterium BB-12 microorganisms were carried out. Counting was done, respectively, on MRS agar, in aerobiosis, and MRS-LP agar, in anaerobiosis, with plates incubated at 37°C for 72 hours. Treatments were arranged in a completely randomized design in split plot, with five treatments: without honey; 5 and 10% honey from Africanized bees, and 5 and 10% honey from Jataí bees. Storage times were evaluated in the split plots. In all treatments, bioyogurt showed counts of 107 CFU g-1 lactic acid bacteria. Probiotic cultures remained viable for 35 days under refrigeration (2-4°C). The interaction between the variation factors affected the probiotic concentration in the bioyogurt. The honeys have a favorable effect on the cell counts of the evaluated microorganisms.

ABSTRACT This study evaluated the effects of crude glycerin (CG) supplied separately from the other dietary ingredients to goats during the feedlot and in the pre-slaughter lairage on the nutrient intake, performance, behavioral and physiological parameters, carcass characteristics, and meat quality. Twenty-eight uncastrated male goats from a cross between the Boer breed and mixed-breed goats were used in a completely randomized design in a 2 × 2 factorial scheme, consisting of the feedlot with or without CG inclusion in the diets (96.90 g kg-1 DM) and the pre-slaughter lairage, also with or without the ingredient. In the feedlot, goats fed CG had a lower intake of dry matter and nutrients. Crude glycerin intake reduced the weight gain and body weight of goats and increased feed conversion. Weights of carcass and cuts (leg, loin, ribs, and shoulder) were lower when the animals consumed CG in the feedlot. In pre-slaughter lairage, concentrations of cortisol were lower when the animals consumed CG. Characteristics of carcass and meat (pH, color, water holding capacity, cooking loss, and shear force) were not changed by the supply of CG during the pre-slaughter. When supplied during the feedlot period and separately from the other dietary ingredients, CG negatively affected the performance and carcass characteristics of goats without changing meat quality. In the pre-slaughter lairage, CG intake lowers the cortisol level and does not change the behavioral parameters or carcass and meat characteristics of goats.

RESUMO. Objetivou-se avaliar os efeitos dos níveis de inclusão da casca de banana seca ao sol na dieta de vacas mestiças sobre a qualidade do queijo Minas frescal e do leite. As dietas foram constituídas de 0, 15, 30, 45 e 60% de substituição da silagem de sorgo pela casca de banana. Foram utilizadas 10 vacas em um delineamento experimental com dois quadrados latinos 5 x 5. Amostras de leite de cada vaca foram analisadas quanto à composição. O leite foi pasteurizado para fabricação do queijo Minas Frescal, que foi pesado para determinação do rendimento e analisado para textura, características físico-químicas e teste de aceitação geral pelo consumidor. O nitrogênio uréico do leite apresentou efeito quadrático com ponto de mínimo ao nível de 43,76% de substituição da silagem pela casca de banana. Os demais itens avaliados na composição do leite e do queijo, bem como os testes de aceitação geral pelo consumidor, não sofreram influência das dietas com inclusão de casca de banana. A substituição de até 60% da silagem de sorgo por casca de banana pode ser uma alternativa viável, pois não altera a composição físico-química do leite e do queijo Minas Frescal, bem como aceitação deste pelos consumidores.

ABSTRACT. This study aimed to evaluate the effects of the inclusion of different levels of sun-dried banana peel in the diet for crossbred cows on the quality of Minas fresh cheese and milk. Diets consisted of 0, 15, 30, 45 and 60% replacement of sorghum silage with banana peel. Ten cows were assigned to two 5 x 5 Latin squares experimental design. Milk samples were taken from each cow and analyzed for composition. Milk was pasteurized for the production of Minas fresh cheese, which was weighed to determine the yield and analyzed for texture, physical and chemical characteristics and consumer acceptance test. Milk urea nitrogen had a quadratic effect with minimum point at 43.76% replacement of silage with banana peel. The remaining items evaluated in the composition of milk and cheese and the consumer acceptance test were not influenced by diets with banana peel. The replacement of up to 60% sorghum silage with banana peel is a viable alternative because it causes no alteration in physical and chemical composition of milk and Minas fresh cheese, as well as consumer acceptance.

RESUMO: Objetivou-se avaliar rendimento, perfil de ácidos graxos, composição físico-química e sensorial do queijo Minas frescal produzido do leite de vacas alimentadas com dietas com diferentes fontes de compostos nitrogenados (farelo de soja, ureia, farelo de girassol e farelo de mamona detoxicado). Foram utilizadas oito vacas F1 Holandesas/Zebu, com produção média de 20 kg de leite corrigido para 3,5% de gordura dia-1, em dois quadrados latinos 4 × 4, sendo compostos de quatro tratamentos (dietas), quatro animais e quatro períodos experimentais cada. Os queijos foram fabricados no último dia de cada período experimental. A composição físico-química, o rendimento e a textura do queijo foram semelhantes entre dietas experimentais. As dietas utilizadas influenciaram a concentração do ácido graxo C11:0, sendo superior para as dietas com farelo de soja e farelo de girassol; o C18:2 C9-T11 (CLA) mostrou-se superior para as dietas com ureia, farelo de soja e farelo de girassol; e o C20:3 para as dietas com farelo de soja e ureia. Para os demais ácidos graxos saturados, monoinsaturados e poli-insaturados não foram observadas diferenças. Diferentes fontes de compostos nitrogenados na dieta de vacas, com produção média de 20 kg de leite corrigido para 3,5% de gordura, não alteram a composição físico-química, o rendimento nem a aceitação do queijo Minas frescal, entretanto pode influenciar o perfil de ácidos graxos da gordura do queijo.

ABSTRACT: This study aimed to evaluate yield, fatty acid profile, physical, chemical and sensory composition of Minas fresh cheese made with milk from cows fed diets containing different sources of nitrogen compounds (soybean meal, urea, sunflower meal and detoxified castor bean meal). Eight F1 Holstein/Zebu cows with average production of 20 kg milk corrected to 3.5% fat day-1 were distributed in two 4 × 4 Latin squares, consisting of four treatments (diets), four animals and four experimental periods. Cheese was produced on the last day of each experimental period. The physical and chemical composition, yield and texture of cheese were similar between diets. The used diets influenced the concentration of fatty acid C11:0, which was higher for diets with soybean meal and sunflower meal; C18:2 C9-T11 (CLA) was higher for diets with urea, soybean meal and sunflower meal and C20:3 for diets with soybean meal and urea. For the other saturated, monounsaturated and polyunsaturated fatty acids, differences were not detected. Different sources of nitrogen compounds in the diet for cows with average production of 20 kg milk corrected to 3.5% fat day-1 have no effect on the physical or chemical composition, yield, as well as acceptance of Minas fresh cheese. However, it can influence the fatty acid profile in the cheese fat.

RESUMO. Este trabalho foi realizado para avaliar o comportamento ingestivo de vacas F1 Holandesas x Zebu alimentadas com crescentes níveis de casca de banana. As dietas foram constituídas de 0, 15, 30, 45 e 60% de substituição da silagem de sorgo pela casca. O delineamento experimental foi dois quadrados latinos 5 x 5. As vacas foram submetidas à observação visual após período de adaptação de cada período experimental. Os tempos despendidos com alimentação (4,13 a 5,58 horas dia-1) e ócio (10 a 12,53 horas dia-1) apresentaram efeito quadrático. O tempo gasto com ruminação, número e duração dos períodos de ruminação, mastigações por bolo e bolos ruminados por dia não foram influenciados pelos níveis de casca. O tempo total de mastigação apresentou efeito quadrático, com ponto máximo no nível de 18,58%. Os níveis de casca de banana não influenciaram consumo, ruminação nem mastigação da fibra em detergente neutro. Consumo, ruminação e mastigação da matéria seca apresentaram efeito linear decrescente. A substituição da silagem de sorgo em até 60% por casca de banana na dieta de vacas em lactação reduz o tempo de alimentação e melhora as eficiências de alimentação e ruminação da matéria seca, mantendo a produção de leite das vacas.

ABSTRACT. This study evaluated the feeding behavior of F1 Holstein x Zebu cows fed increasing levels of banana peel. Diets contained 0, 15, 30, 45 and 60% replacement of sorghum silage with banana peel. The experimental design was two 5x5 Latin squares. Cows were subjected to visual observation after adaptation of each trial period. The times spent in feeding (4.13 to 5.58 hours day-1) and in idle (10 to 12.53 hours day-1) presented quadratic effect. The time spent ruminating, number and duration of rumination periods, chews per cud, and numbers of cuds per day were not affected by treatments. The total chewing time showed a quadratic effect, with peak at 18.58% replacement. The banana peel levels did not affect consumption, rumination and chewing neutral detergent fiber. Intake, rumination and chewing of dry matter showed a decreasing linear effect. The replacement of sorghum silage with banana peel up to 60% in the diet for lactating cows reduces the time spent in feeding and improves feeding and rumination efficiencies of dry matter, keeping the milk production of cows.

RESUMO Analisou-se, por meio de simulação, o efeito do uso de quatro diferentes alternativas de volumosos durante o período da seca na rentabilidade de sistema de produção de leite com vacas F1 Holandês x Gir: 1) uso da cana-de-açúcar in natura (Saccharum officinarum L.) por três meses e silagem de milho (Zea mays L.) por três meses; 2) uso da silagem de milho durante seis meses; 3) uso da silagem de sorgo durante seis meses; e 4) uso da cana-de-açúcar in natura enriquecida com ureia e sulfato de amônio, durante seis meses. A referência zootécnica foi do rebanho composto por vacas F1 Holandês x Gir da Fazenda Experimental de Felixlândia (FEFX) da Empresa de Pesquisa Agropecuária de Minas Gerais (EPAMIG), localizada no município de Felixlândia-MG, região central do estado. O inventário com despesas, receitas e demais dados foram cadastrados no software CUSTO BOVINO LEITE 1.0, visando gerar os resultados para a análise de rentabilidade. A cana-de-açúcar in natura foi a alternativa volumosa com a melhor rentabilidade em sistema de produção de leite com vacas F1 Holandês x Gir, mesmo com um menor volume de leite produzido.

ABSTRACT It was analyzed, by means of simulation, the effect of using four different rougahge alternatives during the dry period on the yield of milk production system using F1 Holstein x Gir cows. The rougahge alternatives were, as follows: 1) use of fresh sugar cane (Saccharum officinarum L.) for three months and corn silage (Zea mays L.) for three months, 2) use of corn silage for six months, 3) use of sorghum silage for six months, and 4) use of fresh sugar cane enriched with urea and ammonium sulfate for six months. The F1 Holstein x Gir herd of the Experimental Farm Felixlândia (FEFX) of the Agricultural Research Corporation of Minas Gerais (EPAMIG), located in the municipality of Felixlândia, state of Minas Gerais, central region of the state was used as reference. The inventory expenses, revenue and other data were registered in CUSTO BOVINO LEITE 1.0 software, aiming to generate the results for the profitability analysis. Fresh sugar cane was the rougahge alternative with the best profitability in milk production system with F1 Holstein x Gir cows, even with a smaller volume of milk produced.

Resumo: Avaliou-se o comportamento ingestivo de vacas F1 Holandês x Zebu com 80 ± 12 dias de lactação e produção média de 20 ± 0,42 kg de leite/dia, alimentadas com diferentes fontes de compostos nitrogenados: farelos de soja, de girassol, de mamona desintoxicados e ureia. Utilizaram-se dois quadrados latinos 4 x 4, compostos de quatro animais e quatro dietas, com quatro períodos experimentais. O comportamento ingestivo foi obtido por avaliação visual para definir o tempo despendido em alimentação, ruminação, ócio e para avaliar mastigações merícicas e tempo de mastigação por bolo ruminal. Não houve diferença no tempo em alimentação (P = 0,1384), ruminação (P = 0,5964), ócio (P = 0,6314), número de períodos de alimentação (P = 0,5995), de ruminação (P = 0,4575) e de ócio (P = 0,4151), duração dos períodos de alimentação (P = 0,2711), ruminação (P = 0,8699) e ócio (P = 0,4025), em função da dieta utilizada. Não houve diferença na produção de leite (P = 0.2755) das vacas entre as dietas experimentais. A adição do farelo de girassol à dieta, em relação à utilização de ureia, resulta em menor consumo de FDN em minutos/kg (P = 0,0399) e consequentemente menor eficiência de alimentação da matéria seca (P = 0,0069), comparado ao tratamento com ureia. Assim, algumas características do comportamento ingestivo de vacas F1 Holandês x Zebu em lactação podem ser alteradas pelo uso de diferentes fontes nitrogenadas; entretanto, sem prejudicar a produção média de 20 kg de leite corrigida para 3,5% de gordura/dia.

Abstract: We evaluated the feeding behavior of F1 Holstein x Zebu lactating cows at 80 ± 12 days of lactation and average production of 20 ± 0.42 kg of milk / day, fed different sources of nitrogen compounds: soybean meal, sunflower meal, detoxified castor meal, and urea. We used two 4 x 4 Latin squares, consisting of four animals, four diets, and four experimental periods. The feeding behavior was obtained by visual evaluation to set the time spent eating, ruminating, idling and to assess ruminating chews and chewing time for ruminal boluses. There was no difference regarding the times spent in feeding (P = 0.1384), rumination (0.5964), idleness (P = 0.6314), number of periods in feeding (P = 0.5995), rumination (P = 0.4575), and idleness (P = 0.4251), duration of periods in feeding (P = 0.2711), rumination (P = 0.8699) and idling (P = 0.4025), depending on the used diet. There was no difference in milk production (P = 0.2755) of the cows among the experimental diets. The addition of sunflower meal to the diet, regarding the use of urea, results in lower consumption of NDF in minutes / kg (P = 0.0399) and, thus, a lesser feed efficiency of dry matter (P = 0.0069). Therefore, some feeding behavior characteristics of F1 Holstein x Zebu lactating cows can be changed by using different nitrogen sources; however, without harming the average production of 20 kg of milk corrected to 3.5% fat / day.