ABSTRACT Nutritional management of high-producing dairy cows under heat stress conditions presents a significant challenge due to the increasing issue of global warming. The study aimed to explore the effects of Cr supplementation in the form of chromium propionate (CrP) on feed intake, lactation performance, and selected biochemical serum parameters in mid-lactation Simmental dairy cows under heat stress conditions. The experiment was conducted during July and August and lasted for 8 wk. The average temperature-humidity index (THI) was 76.45 ± 2.80 during the experimental period, indicating that the cows were under heat stress. The added CrP provided 0.34 mg Cr kg-1 DM of used ration. The supplementation of diet with CrP increased DM intake (4.11%, P < 0.01) and the yield of milk (4.48%, P < 0.01), 4% fat-corrected milk (4.08%, P < 0.01), milk fat (4.46%, P < 0.01), protein (4.21%, P < 0.01), lactose (3.79%, P < 0.01), and total solids (3.51%, P < 0.01). Additionally, CrP supplementation increased blood glucose concentrations (8.39%, P < 0.01), while reducing blood urea N (BUN) levels (14.85%, P < 0.05) and beta-hydroxybutyrate (BHB) levels (17.14%, P < 0.05). The use of CrP as additional dietary source of Cr significantly improved productive performances of dairy cows under heat stress conditions. It was indicated that supplemented Cr could have positive effect on glucose and N metabolism, as well as on energy metabolism of lactating cows at moderately high THI values.

ABSTRACT The use of Mexican sunflower (Tithonia diversifolia [Hemsl.] A. Gray) and high Andean oats (Avena sativa) as promising species in forage banks and silvopastoral systems may be an alternative to improve economic benefits through environmentally sustainable practices. This review work aimed to analyse the potential of a silvopastoral system of high Andean oats and Mexican sunflower and its use in mixed silages as permanent supplementation alternatives for dairy cows. In the high Colombian tropics, Mexican sunflower has been investigated and used as a forage species, both for forage banks and for silvopastoral browsing systems. Likewise, high Andean oats are seen as having potential with high productive yields and great nutritional quality, superior to other commercial varieties. The combination of the two plants offers significant potential for use as mixed silage in dairy cattle supplementation in the high tropics, which could improve production efficiency by enhancing forage availability and quality. This promising approach could help overcome competitiveness and profitability challenges in dairy farming in the high tropics and contribute to more sustainable and profitable production.

RESUMEN La utilización de botón de oro (Tithonia diversifolia [Hemsl.] A. Gray) y avena altoandina (Avena sativa) como especies prometedoras en bancos forrajeros y sistemas silvopastoriles puede ser una alternativa para mejorar el beneficio económico a través de prácticas ambientalmente sostenibles. Este trabajo de revisión tuvo como objetivo analizar el potencial de un sistema silvopastoril de avena altoandina y botón de oro y su uso en ensilajes mixtos como alternativas de suplementación permanente para vacas lecheras. En el trópico alto colombiano se viene investigando y utilizando el botón de oro como especie forrajera, tanto para bancos forrajeros como para sistemas silvopastoriles de ramoneo. Igualmente, se vislumbra como potencial la avena altoandina con rendimientos productivos altos y de gran calidad nutricional, superior a otras variedades comerciales. La combinación de las dos plantas ofrece un potencial significativo para su uso como ensilaje mixto en la suplementación de ganado lechero en el trópico alto, pues podría mejorar la eficiencia productiva al mejorar la disponibilidad y la calidad de los forrajes. Este enfoque prometedor podría ayudar a superar los desafíos de competitividad y rentabilidad en la ganadería de leche en el trópico alto y contribuir a una producción más sostenible y rentable.

Resumo: A genética é um fator que influencia o temperamento dos animais. O objetivo deste trabalho foi comparar vacas holandesas de linhagens neozelandesas (NZ) e norte-americanas (NA) quanto à reatividade avaliada por meio de três testes de temperamento. Foram avaliadas 120 vacas da Unidade Experimental do Instituto Nacional de Investigación Agropecuaria (INIA, Uruguai) de 4 grupos genéticos: NZ ou NA, mantidas sob duas estratégias alimentares: pastejo máximo ou pastejo fixo. A reatividade na ordenha (RO), a velocidade de fuga e a distância de fuga (DF) foram avaliadas em dois períodos (107,5 ± 30,3 e 173,8 ± 32,1 dias de lactação). A média das repetições por animal foi utilizada como variável dependente em modelos lineares gerais que incluíram a genética (NZ ou NA), ordem do parto (primíparas ou multíparas), estratégia alimentar (pastejo máximo ou pastejo fixo), e suas interações como efeitos fixos. Houve interação entre grupo genético e ordem do parto para RO. As diferenças entre vacas NZ e NA foram observadas apenas em multíparas, sendo que vacas NZ apresentaram valores maiores (2,93 ± 1,18) que as vacas NA (2,00 ± 0,90) (P=0,0004). As vacas NZ tiveram maior DF (4,2 ± 1,3 m) que as vacas NA (3,7 ± 1,1 m, P=0,03). A estratégia alimentar não teve efeito nas respostas dos testes. Conclui-se que a origem genética influenciou a reatividade nos testes de temperamento de RO e DF. As vacas NZ foram mais reativas ao homem e à ordenha do que as vacas NA, porém as diferenças na reatividade à ordenha foram observadas apenas em vacas multíparas.

Abstract: Genetics is a factor that influences the dairy cows’ temperament. The objective of the present study was to compare the responses to different temperament tests of New Zealand (NZ) and North American (NA) Holstein cows maintained in two different feeding strategies. A total of 120 cows from the Experimental dairy farm of the National Agricultural and Livestock Research Institute (in Spanish, INIA, Uruguay) were grouped into two Holstein strains: NZ or NA, and two feeding strategies: Grass Maximum or Grass Fixed. Milking reactivity (MR), Flight speed and Distance (FD) were assessed in two periods (107.5 ± 30.3 and 173.8 ± 32.1 days in milk). The averages of these repetitions were used in general linear models with Holstein strains (NZ vs. NA), parity (primiparous vs. multiparous), feeding system (Grass Maximum vs. Grass Fixed), and all two-factor interactions as fixed effects. For MR, there was an interaction between strains and parity. The difference between NZ and NA was observed only for multiparous cows, with higher MR in NZ (2.93 ± 1.18) than in NA (2.00 ± 0.90) (P=0.0004). The NZ cows had longer FD (4.2 ± 1.3 m) than NA cows (3.7 ± 1.1 m) (P=0.03). Feeding system did not affect the cow’s reactivity. In conclusion, dairy Holstein cows’ genetic strain was a factor related to MR and FD tests. In the milking parlor, multiparous NZ cows were more reactive than NA, which did not happen for the primiparous ones. The NZ cows were more reactive to humans than NA in the paddock, exhibiting longer flight distances.

Resumen: La genética es un factor que influye en el temperamento animal. El objetivo de este trabajo fue comparar la respuesta a tres pruebas de temperamento de vacas Holando neozelandesas (NZ) y norteamericanas (NA) bajo dos estrategias de alimentación. Ciento veinte vacas de la Unidad Experimental del Instituto Nacional de Investigación Agropecuaria (INIA, Uruguay) fueron agrupadas en una combinación de dos orígenes genéticos: NZ o NA, con dos estrategias de alimentación: Máximo pasto o Pasto fijo. La reactividad al ordeñe (RO), la velocidad de fuga y la distancia de fuga (DF) fueron evaluadas en dos períodos (107,5 ± 30,3 y 173,8 ± 32,1 días en leche), y el promedio de esas dos mediciones por animal fue utilizado en modelos lineales generales con la genética (NZ vs NA), la paridad (primíparas vs multíparas), la estrategia de alimentación (Máximo pasto vs. Pasto fijo) y sus interacciones como efectos fijos. Hubo una interacción entre origen genético y paridad para la RO. Las diferencias entre vacas NZ y NA fueron solo observadas en multíparas, presentando mayores valores las vacas NZ (2,93 ± 1,18) que las NA (2,00 ± 0,90) (P=0.0004). Las vacas NZ presentaron mayor DF (4,2 ± 1,3 m) que vacas NA (3,7 ± 1,1 m) (P=0,03). La estrategia de alimentación no afectó la respuesta a ninguna prueba. En conclusión, el origen genético de vacas lecheras Holstein influenció la reactividad a las pruebas de temperamento RO y DF. Las vacas NZ fueron más reactivas al humano y al ordeñe que las vacas NA, pero las diferencias en RO fueron solo observadas en vacas multíparas.

Heat stress has been identified as one of the major challenges for livestock production. Global temperatures are steadily increasing, with South African temperatures increasing at nearly twice the global rate. Of the livestock used for food production, dairy cows are the most sensitive to thermal changes, which have detrimental effects on their health, welfare, and overall productivity. Several abiotic factors that influence the heat load experienced by the cow are not commonly included in thermal indices used to measure heat stress; these include solar radiation, wind speed, and soil quality. Furthermore, the thermal comfort zone of cows has been altered by years of intense selection for increased milk yield, causing cows to become heat stressed at lower temperatures. Considering the abiotic and biotic factors affecting the cow's heat load, it can be argued that dairy cows in tropical and subtropical climates are experiencing constant heat stress. In this review, the abiotic and biotic factors influencing the heat load experienced by dairy cows are reviewed, along with the available thermal indices that can be utilised at farm level.

Abstract Objective: To quantify methane emissions from the source of enteric fermentation of cattle on a farm in the Camagüey province, Cuba. Materials and Methods: Emissions of enteric CH4 from 11 milking dairy cows of the Siboney de Cuba (⅝Holstein x ⅜Cebú) species, belonging to the La Liliana farm in Camagüey, were calculated as a local contribution to the updating of the national GHG inventory, for the Agriculture, Forestry and Other Land Uses (AFOLU) module. The 2006 guidelines recommended by the Intergovernmental Panel for Climate Change (IPCC) and the Tier 2 estimation method for the agriculture module were used. Results: Methane emissions from enteric fermentation of milking cows managed at the La Liliana farm in 2023 were 1 326,38 kg CH4/year (37 138,64 kg CO2-eq/year), which confirms it as a key subcategory within the National GHG Inventory for dairy cows. The main elements contributing to the high CH4 emissions were digestibility due to low diet quality, lactation and animal weight. Conclusions: The study on methane (CH4) emissions in Siboney de Cuba cows in the farm show that these emissions are significant and contribute substantially to the greenhouse gas inventory. This underlines the importance of considering dairy cows as a key subcategory in greenhouse gas mitigation.

Resumen Objetivo: Cuantificar las emisiones de metano proveniente de la fuente de fermentación entérica del ganado vacuno en una finca de la provincia de Camagüey, Cuba. Materiales y Métodos: Se calculó las emisiones de CH4 entérico proveniente de 11 vacas lecheras en ordeño de la especie Siboney de Cuba (⅝Holstein x ⅜Cebú), perteneciente a la finca La Liliana en Camagüey, como contribución local a la actualización del inventario nacional de GEI, para el módulo Agricultura, Forestales y otros usos de la Tierra (AFOLU, siglas en inglés). Para ello se utilizaron las guías 2006 recomendadas por el Panel Intergubernamental para el Cambio Climático (IPCC, por sus siglas en inglés) y el método de estimación de nivel 2 para el módulo agricultura. Resultados: La emisión de metano, producto de la fermentación entérica de las vacas en ordeño manejadas en la finca La Liliana en el 2023, fue de 1 326,38 kg CH4/año (37 138,64 kg CO2-eq/año), por lo que se ratifica como una subcategoría clave dentro del Inventario Nacional de GEI para vacas lecheras. Los principales elementos que contribuyeron a las elevadas emisiones de CH4 fueron la digestibilidad por la baja calidad de la dieta, lactancia y el peso del animal. Conclusiones: El estudio sobre las emisiones de metano (CH4) en vacas Siboney de Cuba en la finca muestran que estas emisiones son significativas y contribuyen sustancialmente al inventario de gases de efecto invernadero. Esto subraya la importancia de considerar a las vacas lecheras como una subcategoría clave en la mitigación de gases de efecto invernadero.

ABSTRACT: Bovine mastitis is the most impacting disease of dairy industry, and it is characterized by a complexity of causal agents, which have revealed a geographical variation among regions and countries. The mastitis-related pathogens have been traditionally classified as contagious or environmental, based on habits of the microorganisms and transmission routes. Besides, the severity of mammary infections has been associated with the virulence of the pathogens, and immune and nutritional status of the hosts. Considering this scenario, we investigated the etiological pattern, clinical severity scores, and days in milk (DIM) data in 4,273 clinical cases of bovine mastitis among ten large-dairy farms located in Brazil. Streptococcus dysgalactiae (283/4,273 = 6.6%), Escherichia coli (190/4,273 = 4.4%), Prototheca spp. (112/4,273 = 2.6%), and Streptococcus uberis (95/4,273 = 2.2%) were the predominant pathogens isolated. Among 4,273 clinical cases, clinical severity score was available in 43.8% (1,871/4,273) animals. From these, 69.8% (1,306/1,871), 27.3% (510/1,871), and 2.9% (55/1,871) were scored as mild, moderate, and severe, respectively. Pathogens were observed mainly in samples obtained during the first 100 days in milk, and clinical severity scored mainly as mild. Our results contributed to the etiological identification, clinical severity scoring, and milking aspects of mastitic cows in dairy farms with a history of clinical mammary infections.

RESUMO: A mastite bovina é a doença mais impactante na indústria de laticínios e é caracterizada por uma complexidade de agentes causais, os quais têm revelado uma variação geográfica entre regiões e países. Os patógenos relacionados à mastite têm sido tradicionalmente classificados como contagiosos ou ambientais, com base na fonte de infecção ou origem e nas vias de transmissão. Além disso, a gravidade das infecções mamárias tem sido associada à virulência dos patógenos, e ao estado imunológico e nutricional dos animais. Considerando esse cenário, investigamos os agentes etiológicos, os escores de gravidade clínica e os dados de dias em lactação (DEL) em 4.273 casos clínicos de mastite bovina em dez fazendas de grande porte, quatro localizadas no sudoeste do estado de São Paulo e seis no sul do Estado de Minas Gerais, Brasil. Streptococcus dysgalactiae (283/4.273 = 6,6%), Escherichia coli (190/4.273 = 4,4%), Prototheca spp. (112/4.273 = 2,6%) e Streptococcus uberis (95/4.273 = 2,2%) foram os patógenos predominantes isolados. Entre os 4.273 casos clínicos, a pontuação de gravidade clínica estava disponível em 43,8% (1.871/4.273) dos animais. Desses, 69,8% (1.306/1.871), 27,3% (510/1.871) e 2,9% (55/1.871) foram classificados como leves, moderados e graves, respectivamente. Os patógenos foram observados principalmente em amostras obtidas durante os primeiros 100 dias em lactação, e a gravidade clínica foi principalmente classificada como leve. Nossos resultados contribuem para a identificação etiológica, a pontuação de gravidade clínica e os aspectos de ordenha de vacas com mastite em fazendas leiteiras com histórico de infecções mamárias clínicas.

RESUMO: O monitoramento da ruminação pode ser usado para avaliar a saúde, a reprodução e o bem-estar das vacas leiteiras. O presente estudo teve como objetivo avaliar se o aumento da frequência de ordenha afeta a produção de leite de vacas leiteiras e o perfil de ruminação diária. O banco de dados foi obtido por vacas monitoradas por coleiras contendo sensores de ruminação, que eram ordenhados duas (n = 9 e 379 vacas) ou três (n = 14 e 704 vacas) vezes ao dia. O aumento da frequência de ordenha aumentou (P ≤ 0,05) a produção de leite de 36,0 para 41,6 kg/vaca/d. No entanto, a frequência de ordenha não afetou (P > 0,05) a ruminação diária ou a proporção de ruminação diurna. Em geral, a ruminação diurna (das 7 às 19h) representa 46,3% da ruminação diária. Vacas ordenhadas duas vezes ao dia apresentaram grande redução na taxa de ruminação, especialmente durante a segunda ordenha diária, em comparação com vacas ordenhadas três vezes ao dia. Assim, a frequência da ordenha afeta a produção de leite e a redução da ruminação durante a ordenha. No entanto, não afeta a ruminação diária e a proporção da ruminação diurna e pode ser utilizado como um indicador de risco de acidose, independentemente da frequência de ordenhas utilizada na propriedade.

ABSTRACT: Rumination monitoring assesses dairy cows’ health, reproduction, and welfare status. The present study evaluated whether increasing the milking frequency affects dairy cows’ milk yield and daily rumination profile. The database was obtained from cows monitored using collars equipped with a rumination sensor. Cows were milked two (n = 9 and 379 cows) or three (n = 14 and 704 cows) times daily. Increased milking frequency improved (P ≤ 0.05) milk yield from 36.0 to 41.6 kg/cow/d. However, the milking frequency did not affect (P > 0.05) daily rumination or the proportion of diurnal rumination. Diurnal rumination (from 7 to 19 h) generally represents 46.3% of daily rumination. Cows milked twice daily showed a significant decrease in rumination rate, especially during the second daily milking, compared to cows milked three times daily. Thus, milking frequency affects milk yield and reduces rumination during milking. However, it does not affect daily rumination and the proportion of diurnal rumination and can be used as an acidosis marker regardless of milk frequency.

Abstract This study aimed to characterize the reproductive parameters and economic indicators of dairy farms. Data were from technical assistance of the Programa de Desenvolvimento em Pecuária Leiteira (PDPL-UFV) including 26 farms, from September 2022 to August 2023, comprising an entire production cycle. The following economic indicators were selected as dependent variables: Unit Net Margin (UNM), Operating Profitability (OP) and Rate of Return on Capital (RRC). Reproductive parameters were used as explanatory variables in multiple linear regression analysis. A stepwise selection was performed and only variables significant at p < 0.10 were kept in the final model. Pregnancy rate of cows, number of inseminations per pregnant heifer, and replacement rate were the reproductive parameters with the greatest effect on the evaluated economic indices. The UNM and OP were positively affected by pregnancy rate of cows and number of inseminations per pregnant heifer, but replacement rate negatively affected both indices. Only the pregnancy rate of cows showed a significant and positive effect on RRC. Results suggest that the economic viability of a dairy farm is not only associated with cutting costs such as reducing the number of inseminations in heifers, or increasing revenue by selling animals, which increases the replacement rate.

ABSTRACT The objective of this study was to analyze dairy farm characteristics as a function of milk urea nitrogen (MUN) content in the north and west of the state Paraná, Brazil. Milk urea nitrogen serves as an indicator of protein utilization by cows. In view of the high costs of protein in animal diets, this study evaluated farm characteristics that could influence MUN content. For this, 32 dairy farms were randomly selected for application of a questionnaire assessing qualitative and quantitative variables. Interviews and samplings of bulk tank milk were carried out from October 2018 to October 2019. Three clusters of farms were identified: cluster 1, low MUN content (8.07 mg/dL); cluster 2, high MUN content (21.60 mg/dL); and cluster 3, intermediate MUN content (11.90 mg/dL). Clusters 1, 2, and 3 comprised 19, 4, and 9 farms, respectively. No association was found between MUN content and production system (conventional or agroecological). However, clusters differed significantly (P<0.05) in total number of cows and number of lactating cows. Differences (P<0.05) were also found for milk fat and total solids contents. As MUN is highly influenced by diet protein levels and the analyzed farms used feed based on the same ingredients (corn and soybean), it was not possible to identify which factors influenced MUN content for the studied farm groups.

ABSTRACT. Little information exists on effectiveness of the approach in the intervention programme delivered to smallholder dairy farmers. A comparative study was conducted to assess milk production and composition in two districts (Doyogena project area and Angacha as a control) and the associated dairy intervention. Data were collected through household survey and milk testing. The average daily milk yield of crossbred dairy cows was 6.91±1.14 litres, which was significantly (p < 0.05) different across districts. The overall mean fat, solids-not-fat, lactose, salts, protein, and total solids (TS) contents of crossbred cows’ milk were 4.71±0.83, 8.85±0.36, 4.87±0.19, 0.72±0.03, 3.23±0.13 and 13.55±0.19 percent, respectively. The milk composition was significantly (p < 0.05) different across the study areas. Milk fat content is higher than the Ethiopian standard (ES); protein is also comparable. The major constraints for dairy production in the study areas were, in descending order, feed shortage in the dry season, land scarcity, lack of improved breeds, market access, and disease prevalence. To make livestock programs more impactful, strong extension and an integrated approach that encompasses improved feeds, breeding, marketing, and better health management are crucial to alleviate the diverse constraints of smallholder dairying while enhancing productivity and the associated food and nutrition security and livelihoods.

RESUMO O presente estudo avaliou os efeitos de doenças do pós-parto e do escore de condição corporal (ECC) sobre a performance reprodutiva de rebanhos leiteiros. As vacas foram monitoradas durante o pós-parto para diagnosticar doenças e mudanças no ECC. Elas foram divididas entre aquelas sem doença e as com uma ou mais doenças. A incidência de doenças, a taxa de concepção (TC) no primeiro serviço pós-parto, a taxa de serviço, o percentual de vacas prenhas aos 150d e a perda gestacional foram analisados. Não foram observadas diferenças entre vacas saudáveis e doentes com relação à TC ou à taxa de serviço. Vacas com doença apresentaram maior perda gestacional, e a porcentagem de vacas prenhas aos 150 dias foi maior entre vacas saudáveis. Vacas com ECC ≥ 3,0 no pré-parto tiveram menor TC no primeiro serviço e menor taxa de serviço. Em conclusão, rebanhos leiteiros acometidos por doenças no pós-parto apresentam eficiência reprodutiva prejudicada.

ABSTRACT This study evaluated the effects of postpartum diseases and body condition score (BCS) on the reproductive performance of dairy herds. Cows were monitored during the postpartum to diagnose diseases and changes in BCS. The cows were divided into those with no disease and those with one or more diseases. The incidence of diseases, pregnancy rate (PR) at the first postpartum service, number of days open, percentage of pregnant cows at 150d, and gestational loss were analyzed. No difference was observed between healthy and diseased cows in the PR at the first service or for days open. Diseased cows showed greater gestational loss and the percentage of pregnant cows at 150d postpartum was higher among healthy cows. Cows with a BCS ≥ 3.0 at prepartum had a lower PR at the first service and shorter days open. In conclusion, dairy herds affected by diseases during postpartum show impaired reproductive efficiency

Resumo A indigestão vagal (IV) é uma síndrome caracterizada por alterações na motilidade dos pré-estômagos e do abomaso, resultante de disfunções no nervo vago. Embora diversas condições inflamatórias estejam associadas à lesão nervosa, a relação entre abscessos peri-hepáticos e IV ainda é pouco documentada. Diante disto, realizou-se um estudo retrospectivo dos achados clínicos, laboratoriais, ultrassonográficos e anatomopatológicos de 15 bovinos diagnosticados com IV em decorrência de abscesso peri-hepático. Amostras oriundas dos abscessos hepáticos de três bovinos foram encaminhadas para a análise bacteriológica. Todos os animais tinham idade acima de 24 meses, eram fêmeas de aptidão leiteira em fase produtiva (86,67%, 13/15) e criados em sistema semi-intensivo (73,34%, 11/15). Os principais achados clínicos observados foram desidratação, timpania ruminal, hipermotilidade ruminal e fezes escassas. Os exames laboratoriais revelaram leucocitose por neutrofilia com desvio à esquerda regenerativo, além de elevação do teor de cloretos do fluido ruminal. No exame ultrassonográfico, constataram-se hipermotilidade reticular, distensão ruminal e grandes abscessos adjacentes ao lobo hepático esquerdo, confirmados na avaliação anatomopatológica. Na análise bacteriológica, foram identificados Staphylococcus aureus, Enterococcus faecalis e Providencia stuartii. Conclui-se que, dentre as causas da síndrome da IV, a presença de abscessos peri-hepáticos deve ser considerada no estabelecimento do diagnóstico da enfermidade.

Abstract Vagal indigestion (VI) is a syndrome characterized by changes in the motility of the forestomach and abomasum, which occurs in the event of dysfunctions in the vagus nerve. Several inflammatory conditions are associated with nerve injury, however, the relationship between perihepatic abscesses and this syndrome is poorly documented. Therefore, a retrospective study of the clinical, laboratory, ultrasound and anatomopathological findings of 15 cattle presented with VI due to perihepatic abscess was carried out. Samples from the liver abscesses of three cattle were sent for bacteriological analysis. All were over 24 months old, were dairy cows in the productive phase (86.67%, 13/15) and raised in a semi-intensive system (73.34%, 15/11). The main clinical findings were dehydration, ruminal tympania, ruminal hypermotility and scanty feces. Laboratory tests revealed leukocytosis due to neutrophilia, with a regenerative shift to the left and elevated chloride content in the ruminal fluid. Ultrasonography revealed reticular hypermotility, ruminal distension and large abscesses adjacent to the left hepatic lobe, which were confirmed by pathological examination. Bacteriological evaluation identified Staphylococcus aureus, Enterococcus faecalis and Providencia stuartii. It is concluded that among the causes of IV syndrome, the presence of perihepatic abscesses should be considered when establishing the diagnosis of the disease.

Abstract Repeat breeder (RB) syndrome plays a detrimental role on fertility and economic performance of dairy farms. Regarding its multifactorial origin, it has been stated that an immunological response in the female genital tract may impair sperm viability. Therefore, the aim of this study was to evaluate the concentration of immunoglobulins in cervical mucus of RB cows and its influence on sperm motility. Fifteen fertile cows and 32 RB cows were included in the study. Cervical mucus samples were collected at the time of artificial insemination (AI). The concentration of IgG and IgA was determined by radial immunodiffusion. Sperm motility in cervical mucus was evaluated by CASA system. Our results showed no significant differences between cows with or without RB syndrome regarding the concentration of immunoglobulins in cervical mucus and sperm motility. The only factor affecting sperm motility was time. Consequently, it may be probable that a local immune response against spermatozoa is not one common cause of RB syndrome.

RESUMO Objetivou-se com este trabalho determinar o efeito do tamanho de partículas e da inoculação em silagem milheto comparada à silagem de milho em dietas de vacas mestiças 3/4 Holandês × 1/4 Gir, sob o consumo e digestibilidade das dietas, bem como, a produção e composição do leite. Foram utilizadas cinco vacas, com 100 ± 26 dias em lactação e peso corporal (PC) médio de 509 ± 53 kg, em delineamento experimental em quadrado latino 5 × 5. Foram avaliadas nas dietas, silagem de milheto com 5 ou 20 mm de tamanho de partículas, inoculadas ou não com Propionibacterium acidipropionici e Lacticplantibacillus plantarum, e comparadas com silagem de milho. Vacas alimentadas com silagem de milho apresentaram maiores consumo de matéria seca (MS), matéria orgânica (MO), carboidratos totais (CT) e fibra em detergente neutro (FDN) do que vacas alimentadas com dietas contendo silagem de milheto. A digestibilidade da MS da dieta contendo silagem de milho foi maior do que das dietas contendo silagem de milheto. Vacas alimentadas com dieta contendo silagem de milho produziram mais leite do que as vacas alimentadas com dietas contendo silagem de milheto. Vacas alimentadas com dietas contendo silagem de milheto com 20 mm de tamanho de partículas comparadas as de 5 mm apresentaram melhor eficiência produtiva, 1,05 e 0,94 kg de leite kg-1 de MS consumida, respectivamente. Vacas alimentadas com dietas contendo silagem de milho produziram mais leite do que vacas alimentadas com dietas contendo silagem de milheto.

ABSTRACT The objective of this study was to determine the effect of particle size and inoculation in millet silage compared to corn silage in diets of crossbred 3/4 Holstein × 1/4 Gir cows on diet intake and digestibility, as well as milk production and composition. Five cows were used, with 100 ± 26 d in lactation and a mean body weight (BW) of 509 ± 53 kg, in a 5 × 5 Latin square experimental design. Millet silage with 5 or 20 mm particle size, inoculated or not with Propionibacterium acidipropionici and Lactiplantibacillus plantarum, was evaluated in the diets, and compared with corn silage. Cows fed with corn silage showed a higher intake of dry matter (DM), organic matter (OM), total carbohydrates (TC), and neutral detergent fiber (NDF) than cows fed diets containing millet silage. The DM digestibility of the corn silage diet was higher than that of the diets containing millet silage. Cows fed a diet containing corn silage produced more milk than cows fed diets containing millet silage. Cows fed diets containing millet silage with 20 mm particle size compared to 5 mm showed better productive efficiency, 1.05 and 0.94 kg of milk/kg of DM intake, respectively. Cows fed diets containing corn silage produced more milk than cows fed diets containing millet silage.

ABSTRACT This study aimed to use the daily maximum temperature and humidity index (THImax) to calculate the ratio between average milk composition in the three hottest (stress) and three mildest months (comfort) of the year in an important milk-producing region in Brazil, with potential practical application in other tropical regions. The study was conducted in the municipalities of Araxá, Sacramento, and Uberaba in Minas Gerais State, from 2017 to 2020. THImax was calculated using daily maximum temperature and minimum relative humidity data. The three months with the largest number of days with THImax ≥ 76 were classified as the stress period, and the three months with THImax < 76 as the comfort period. Average fat, protein, and lactose content, total solids, and non-fat solids were calculated for both periods using 10,063 milk composition analyses, and the stress-to-comfort (S:C) ratio of the milk components was determined. Fat content declined during the stress period, with an S:C ratio below 1.0. Most ratios were also below 1.0 for protein and total solids, while values for lactose and non-fat solids showed minimal deviation from 1.0. THImax values ≥76 significantly alter the milk composition of crossbred dairy cows in tropical regions, largely by decreasing the fat content, resulting in an S:C ratio below 1. Determining the milk composition ratio between the hottest and mildest months enables the identification of thermal discomfort in crossbred cows in tropical regions and provides a practical tool for dairy producers to monitor heat stress.

RESUMO Objetivou-se calcular a razão da composição média do leite entre os três meses mais quentes (Estresse) e os três meses mais amenos (Conforto) baseado no THImax diário em uma importante região produtora de leite, Minas Gerais, Brazil, o que pode servir para aplicação prática em outras regiões tropicais. Este estudo foi realizado nas regiões de Araxá, Sacramento e Uberaba, Minas Gerais, Brasil de 2017 a 2020. Calculou-se o ITUmax com dados diários de temperatura máxima e umidade relativa mínima. Os três meses com maior número de dias com ITUmax ≥76 foi considerado estresse e os três com ITU <76 como conforto. Depois, calculou-se as médias de gordura, proteína, lactose, sólidos totais e sólidos não gordurosos de leite nos períodos estresse e conforto utilizando 10.063 análises. Depois, calculou-se a razão Estresse/Conforto dos componentes do leite. Houve redução no teor de gordura durante o estresse, com razão Estresse/Conforto abaixo de 1,0, enquanto a maioria das razões para proteína e sólidos totais também ficou abaixo de 1,0. Para lactose e sólidos não gordurosos os valores diferiram pouco de 1,0. Valores de ITUmax ≥ 76 provocam alterações na composição do leite de vacas mestiças leiteiras em regiões tropicais, principalmente com redução no teor de gordura, gerando uma relação Estresse/Conforto menor que 1. A determinação da relação entre a composição média do leite nos três meses mais quentes e nos mais amenos permite identificar o desconforto térmico de vacas mestiças em regiões tropicais e pode ser utilizado pelos produtores de leite para monitorar o estresse térmico.