Temperature-humidity index and reproductive performance of dairy cattle farms in Lima, Peru.

Background: Heat stress results in a mild reduction in milk production, while long-term heat stress exposure can severely affect the productive and reproductive performance in dairy cattle. Aim: To quantify the relationship between reproductive performance and temperature-humidity index in dairy cattle farms in Lima, Peru. Methods: Monthly service, conception, and pregnancy rates were measured from four dairy farms in four different Lima localities as reproductive performance indicators, along with an index of heat stress and maximum daily temperature-humidity index (max THI), during a 3-year period. In order to establish the relationship between the max THI and the reproductive performance indicators, a multiple regression analysis was carried out, which considered farm and year as explicative variables. Results: The regression model showed an adjusted R2 of 33.5% with an estimated standard error of 5.75% and was highly significant (p < 0.001). The regression coefficients for max THI for the variables pregnancy rate and conception rate were significant (p < 0.0001). With every increasing unit of max THI, a 0.84% drop in the pregnancy rate and a 1.74% drop in the conception rate were estimated by the model. The regression coefficient of max THI for the service rate variable was not significant. Conclusion: It was concluded that the increase in max THI significantly affected the reproductive performance of intensive dairy cattle farms in Lima.

Effect of probiotics administration at different levels on the productive parameters of guinea pigs for fattening (Cavia porcellus).

Background: For more than 50 years, antibiotics have been used to maintain animal welfare and improve efficiency. Recently, antibiotics were found in the muscle, liver, and kidney of guinea pig carcasses put up for sale and human consumption, which is a public health issue. Probiotics are supplements of live microorganisms that, when administered in adequate doses, could replace growth-promoting antibiotics. Aim: This study analyzed the effect of the administration of an oral probiotic mixture on the guinea pigs productive performance (Cavia porcellus). Methods: Fifty male guinea pigs, weaned at 14 days of age, were distributed in a completely randomized design of five treatments with ten repetitions for each group. The treatments were CONTROL group without probiotic; PROB 1 given 1 ml of probiotic; PROB 2 with 2 ml of probiotic; PROB 3 with 3 ml of probiotic; and antibiotic growth promoter (AGP) was given 300 ppm zinc bacitracin. The microorganisms used in the probiotic were Enterococcus hirae, Lactobacillus reuteri, Lactobacillus frumenti, Lactobacillus johnsoni, Streptococcus thoraltensis, and Bacillus pumilus. Productive parameters were evaluated from weaning to 70 days of age. Results: No statistically significant difference was found between the treatments on forage dry matter intake (DMI), concentrateconcentrate DMI, or total concentrate DMI (p > 0.05). Similarly, no statistical difference was found between the treatments in terms of final weight or weight gain (p > 0.05). Regarding the feed conversion ratio (FCR), there was a significant difference between treatments (p = 0.045); the CONTROL group had the highest FCR, followed by the AGP group, with the best FCR observed in the PROB 3 group (p < 0.05). In addition, significant statistical differences were found between CONTROL and PROB 2 (p < 0.05). Likewise, a significant linear effect of increasing doses of the probiotic was found (p = 0.01), which indicated that the feed conversion was better with a higher dose. Conclusion: The treatments evaluated in this study significantly impacted the FCR in guinea pigs for fattening. Increasing doses of probiotics had a linear effect on FCR.

Efficacy of physical and chemical treatments on the inactivation of bovine leukosis virus present in milk.

PURPOSE: The objective of the present study was to evaluate the efficacy of pasteurization, freezing, the addition of formaldehyde and peroxymonosulfate on the inactivation of the bovine leukemia virus (BLV) present in milk. MATERIALS AND METHODS: A sheep bioassay was carried out in 40 sheep, which were intraperitoneally inoculated with leukocytes from milk infected by the BLV previously treated with one of the virus inactivation methods. Five study groups were evaluated: (1) control group: milk without previous treatment, (2) pasteurization group: milk treated by pasteurization, (3) freezing group: milk treated by freezing for 36 hours, (4) formaldehyde group: 0.1% formaldehyde, and (5) peroxymonosulfate group: 0.05% peroxymonosulfate. The inoculated animals were followed for 10 weeks. RESULTS: At week 10 post-inoculation, all the animals (8/8) of the control group and the peroxymonosulfate group were seropositive to BLV, while no animals were seropositive (0/8) to BLV in the remaining three groups. Statistically significant differences were found between the pasteurization, freezing and formaldehyde groups with respect to the control (p<0.001) and peroxymonosulfate groups (p<0.001). CONCLUSION: The results indicate that pasteurization, freezing and formaldehyde processes are efficient in inactivating the BLV and can be used in milk to prevent the transmission of the virus.

Inclusion of different levels of inulin on productive parameters and intestinal morphology in fattening guinea pigs (Cavia porcellus) / Efeito da inclusão de diferentes níveis de inulina nos parâmetros produtivos e na morfologia intestinal em cobaias de engorda (Cavia porcellus)

ABSTRACT: This study evaluated the effect of the three inulin levels (0.1%, 0.2%, 0.4%) supplemented as a substitute for an antibiotic growth promoter (AGP, zinc bacitracin) and control in guinea pigs raised for human consumption. Fifty 14-day-old male guinea pigs were used. Productive parameters (weight gain, total dry matter intake, and feed conversion ratio (FCR)) and intestinal morphology of the duodenum, jejunum, and ileum at slaughter (70 days of age) were evaluated. An inverse relationship was observed between inulin levels and FCR (linear effect; P = 0.006). There was no statistically significant effect of the treatments on total dry matter intake and weight gain (P > 0.05). A linear effect of the inulin level on the villi's length (VL), villi's width (VW), and length/depth ratio (VL/DC) in the duodenum; VW in the jejunum; and VL in the ileum (P <0 .05) was reported. In conclusion, a linear effect of the increasing doses of inulin was found on the FCR and the morphological parameters of the duodenum's integrity, and no differences in the effects of the inulin added to the diet and the treatment with AGP were found.

RESUMO: O objetivo do estudo foi avaliar o efeito da suplementação na dieta de cobaias com inulina, em níveis crescentes (0,1%, 0,2%, 0,4%) como substituto para um antibiótico promotor de crescimento (AGP, bacitracina de zinco) além do grupo controle (dieta padrão). Foram utilizados 50 porquinhos-da-índia machos com 14 dias de idade. Os parâmetros produtivos foram avaliados do desmame aos 70 dias de idade e os parâmetros morfológicos intestinais foram avaliados no duodeno, jejuno e íleo no momento do abate. Foi encontrado um efeito linear do nível de inulina sobre na taxa de conversão alimentar (FCR; P = 0,006), indicando que em níveis mais elevados de inulina o FCR diminui. Não houve diferença significativa entre os grupos quando avaliado o efeito dos diferentes tratamentos sobre o consumo de ração e ganho de peso corporal (P > 0,05). Um efeito linear do nível de inulina foi encontrado no comprimento das vilosidades (VL), na largura das vilosidades (VW) e na relação comprimento / profundidade (VL/DC) no duodeno, sobre a VW no jejuno; e no VL no íleo (P < 0,05). Em conclusão, um efeito linear do aumento do nível de inulina foi encontrado na taxa de conversão alimentar e nos parâmetros morfológicos da integridade do duodeno, além disso, não houve diferença entre a adição de inulina na dieta e o tratamento com um antibiótico promotor de crescimento.

Efecto de dilutores en base a Tris, Tes y leche descremada en la criopreservación de espermatozoides obtenidos del epidídimo de alpaca / Effect of extenders based on tris, tes and skim milk on cryopreservation of epididymal alpaca sperm

El estudio tuvo por objetivo evaluar el efecto de tres dilutores (Tris, Tes y leche descremada) en la criopreservación de espermatozoides obtenidos del epidídimo de alpaca. Previamente se determinó el efecto del tiempo entre el beneficio/castración y la recuperación de los espermatozoides del epidídimo. Se utilizaron 24 testículos de alpacas para la obtención de los espermatozoides directamente del epidídimo en una solución fisiológica buferada (PBS). La recuperación de espermatozoides se realizó a las 0, 35, 48 y 72 horas (6 testículos por grupo) y se evaluó la motilidad, concentración espermática e integridad funcional de membrana. Los espermatozoides recuperados a partir de 35 horas post beneficio/castración no fueron aptos para ser congelados. Las muestras recuperadas a las 0 horas fueron diluidas con Tris, Tes y leche descremada, enfriadas desde 35 a 5°C en 90 minutos, envasadas en pajillas de 0.25 ml y congeladas en nitrógeno líquido. Se evaluó la motilidad, integridad funcional de membrana y vitalidad/integridad acrosomal en las muestras descongeladas. La motilidad fue de 14.0, 8.6 y 17.0% en los grupos Tris, Tes y leche descremada, respectivamente, donde el grupo leche descremada fue significativamente mejor que el grupo Tes (p<0.05). Los porcentajes de integridad funcional de membrana y vitalidad/integridad acrosomal fueron similares entre los tres grupos. Se concluye que los tres dilutores brindan efectos similares para la criopreservación de espermatozoides epididimarios de alpaca.

The objective of this study was to evaluate the effect of three semen extenders (skim milk, Tris, and Tes) on cryopreservation of epididymal alpaca sperm. Previously, the effect of timespan since slaughtering or castration to the recovery of epididymal sperm was evaluated. Twenty-four alpaca testicles were used to obtain sperm from the epididymis in a buffered saline solution (PBS). The recovery of spermatozoa was performed at 0, 35, 48, and 72 hours (6 testes per group) after slaughtering or castration. Sperm motility, concentration, and sperm membrane functional integrity were analyzed. Sperm recovered after 35 hours was not usable for cryopreservation. Sperm samples recovered at 0 hours were subjected to the process of freezing. Samples were diluted with skim milk, Tris, and Tes, cooled from 35 to 5 °C in 90 minutes, packed into 0.25 ml straws and frozen in liquid nitrogen. After thawing, straws were evaluated by motility, sperm membrane functional integrity and vitality/acrosome integrity. Motility was 17.0, 14.0, and 8.6% on skim milk, Tris and Tes groups respectively, where the skim milk group was significantly better than the Tes (p<0.05). Percentages of sperm membrane functional integrity and vitality/acrosomal integrity were similar among the three extenders. It was concluded that all three extenders provided similar effects for the cryopreservation of epididymal alpaca spermatozoa.

Criopreservación de semen ovino empleando tres dilutores y cuatro combinaciones de agentes crioprotectores permeantes y no permeantes / Ovine semen cryopreservation using three extenders and four combinations of permeant and non permeant agents

El objetivo del estudio fue evaluar el efecto de tres dilutores y cuatro combinaciones de dos agentes crioprotectores permeantes más dos no permeantes sobre la calidad del semen ovino post-descongelamiento. Para esto, en una primera fase se evaluaron entre tres dilutores (A, B y C) y el más adecuado se usó en una segunda fase, donde se evaluaron las siguientes combinaciones de agentes crioprotectores permeantes y no permeantes: 1) Glicerol - Trehalosa, 2) Glicerol - Sacarosa, 3) Etilenglicol - Trehalosa y 4) Etilenglicol - Sacarosa. En el experimento 1, se encontró que el Dilutor A mantenía mejor la motilidad progresiva, viabilidad e integridad acrosomal post-descongelamiento en comparación con los dilutores B y C, por lo que el Dilutor A se empleó en el experimento 2. En este ensayo se encontró que la motilidad progresiva, la viabilidad e integridad acrosomal, la termoresistencia y la integridad de membrana plasmática post-descongelamiento fue mejor en los grupos con glicerol-sacarosa y glicerol-trehalosa en comparación con los grupos con etilenglicol-sacarosa y etilenglicol-trehalosa. Esto demuestra que el glicerol es un mejor crioprotector permeante en comparacion con el etilenglicol; sin embargo, no hubo diferencia en el uso de sacarosa o trehalosa. Se concluye que un dilutor con las características del dilutor A, utilizando glicerol más trehalosa o sacarosa, constituye una buena alternativa para la criopreservación de semen ovino.

The objective of the study was to evaluate the effect of three extenders and four combinations of two permeant and two non permeant cryoprotectant agents on the quality of post thaw ram semen. In Experiment 1, three extender were evaluated (A, B, and C) in order to select the best for the next step. In Experiment 2, different combinations of cryoprotectant agents were evaluated as follow: 1) Glycerol–Trehalose, 2) Glycerol–Sucrose, 3) Ethylene glycol-Trehalose, and 4) Ethylene glycol–Sucrose. In experiment 1, motility, viability and acrosomal integrity in extender A were higher than in extender B and extender C, and therefore, extender A was used for experiment 2. In this assay, motility, viability and acrosomal integrity, thermoresistance, and plasmatic membrane integrity were higher in groups Glycerol-sucrose and Glycerol-trehalose in comparison with groups Ethilene glycol-sucrose and Ethilene glycol-trehalose. However, there were not significative differences between sucrose or trehalose. In conclusion, an extender with characteristics of extender A using glycerol plus trehalose or sucrose constitute a good alternative for cryopreservation of ram semen.

Efecto de dos antioxidantes (tempo y tempol) en la criopreservación de semen ovino empleando un dilutor en base a tris / Effect of two antioxidants (tempo and tempol) on ram semen cryopreservation using the tris extender

Se emplearon 32 muestras de semen procedentes de cuatro ovinos a fin de ser criopreservadas con la adición dos antioxidantes: Tempo (2,2,6,6 tetrametil-1-piperidiniloxil) y Tempol (4-hidroxi 2,2,6,6 tetrametil-1-piperidiniloxil), en concentraciones de 0.5, 1.0 y 2.5 mM, para evaluar el efecto postdescongelamiento que pudieran tener sobre la motilidad progresiva, la viabilidad e integridad acrosomal y la capacitación espermática prematura. En cada concentración de los dos antioxidantes y del grupo control se utilizó un dilutor en base a Tris, realizándose ocho repeticiones, cada una con cuatro muestras de semen. Los resultados obtenidos demuestran que la adición de Tempo a una concentración de 0.5 mM mejora significativamente la calidad del semen criopreservado en comparación con el grupo control (p<0.05), incrementado los porcentajes de motilidad progresiva (79 vs. 67 por ciento), viabilidad e integridad acrosomal (70 vs. 58 por ciento) y reduciendo la capacitación espermática prematura (9 vs.15 por ciento). Por otro lado, la adición de Tempol disminuyó la calidad seminal postdescongelamiento en comparación con el control. En conclusión, la adición de Tempo 0.5 mM en un dilutor en base a Tris, al finalizar la fase de enfriamiento, podría constituir una estrategia para mejorar la calidad de semen ovino criopreservado.

Thirty-two semen samples from four rams were frozed using two antioxidants, Tempo (2,2,6,6 tetramethyl-1-piperidinyloxyl) and Tempol (4-hidroxi 2,2,6,6 tetramethyl-1-piperidinyloxyl), each one in concentrations of 0.5, 1.0, and 2.5 mM, to evaluate the effects on post-thawing motility, viability, acrosomal integrity, and earlier sperm capacitation. Eight replications for each antioxidant concentration and control group, were done using four semen samples per replication. Semen samples were diluted on a Tris extender. Results showed that Tempo 0.5 mM improved frozen semen quality in comparison with control group (p<0.05), by increasing progresive motility (79 vs. 67 por ciento), viability and acrosomal integrity (70 vs. 58 por ciento), and decreasing earlier sperm capacitation (9 vs. 15 por ciento). On the other hand, Tempol decreased frozen semen quality. In conclusion, the use of Tempo 0.5 mM on a Tris extender, at the end of the cooling process, could be an alternative for improving the quality of frozed ram semen.