A single administration of carbetocin before electroejaculation increases the insemination doses produced from each ejaculate in rams

The aim of the study was to determine the effect of carbetocin administration (a long-acting analog of oxytocin) 20 or 10 min before electroejaculation (EE) on the duration of semen collection procedure, quantitative and qualitative characteristics of the ejaculate, and stress biomarkers in rams. Semen was collected from 12 Corriedale rams (age, 2.5-5.5 years old) with EE, in a Latin-square design, administrating carbetocin (0.2 mg/100 kg of body weight i.v.) 20 or 10 min before EE, or without carbetocin administration (CB-20, CB-10, and CON treatments, respectively). Each treatment was applied to different rams every 3-4 days, allowing all the rams to receive all three treatments. Carbetocin administered 20 or 10 min before EE increased the number of sperm ejaculated (P = 0.01), the semen concentration (P = 0.02), the number of insemination doses collected in a single collection (P = 0.01), and the number of insemination doses collected/electrical pulses administered (P = 0.05) compared to control rams. Carbetocin administered 20 or 10 min before semen collection prolonged the time required for EE and the number of pulses administered during EE compared to CON rams (P < 0.03 for both). The CB-10 rams required the administration of more electrical pulses during ejaculation than CON rams (P = 0.001), and CB-20 treatment tended to require more electrical pulses than CON rams (P = 0.06). The volume of the ejaculate was greater in CB-10 than in CON rams (P = 0.01), and that of CB-20 treatment tended to be greater than CON rams (P = 0.08). The percentage of sperm with intact membrane was greater in CB-20 than in CON rams (P = 0.01). Total protein, albumin, and globulin concentrations were lower immediately after carbetocin administration 20 or 10 min before EE. The treatments did not affect cortisol concentration, glycemia, rectal and surface temperatures, heart rate, and facial expressions. Carbetocin administration before EE of rams improved the quantitative and qualitative characteristics of the ejaculate, duplicating the number of insemination doses collected. It can be a promising treatment to obtain a greater quantity of doses to inseminate with a lower frequency of semen collections, reducing the negative impacts of EE on animal welfare.

Daily variation of the cortisol and insulin concentration, glycemia, surface temperature, and behavior patterns due the administration of equine Chorionic Gonadotropin in rams

Sex steroids can modulate the circadian rhythmicity of some physiological and behavioral functions of sheep. During the non-breeding season, Corriedale rams have a low testosterone concentration, but the administration of equine Chorionic Gonadotropin (eCG) stimulates its secretion. Therefore, the daily variation of cortisol and insulin concentrations, glycemia, behavioral pattern (eating, ruminating, standing, lying, and sleeping), and rostral and eye surface temperatures were compared in rams treated or not treated with eCG during the non-breeding season [between August (late winter) and September (early spring)]. Twenty Corriedale adult rams (BW 63.4 ± 7.3 kg; BCS: 3.5 ± 0.5; mean ± SD; age: 2-3 years old) were randomly assigned to 1 of 2 treatments: a) Treated: administration of 1000 IU of eCG intramuscularly and b) Control: control, without application of eCG. All the rams were managed under the same feeding and environmental conditions (individual pens outdoors). All variables were measured each hour for 26 h, except testosterone and insulin that were measured at 09:00, 10:00, 12:00, 15:00, 18:00, 21:00, 22:00, 24:00, 03:00, 06:00, 09:00 and 11:00 h. Testosterone and cortisol concentration were greater in Treated than Control rams (testosterone: 32.7 ± 0.7 nmol/L vs 5.8 ± 0.7 nmol/L; P <0.0001; cortisol: 11.3 ± 0.6 nmol/L vs 9.9 ± 0.6 nmol/L; P =0.02). The eye surface temperature was 0.9°C lower in the Treated than in the Control rams (P =0.004). The characteristics of the daily variation pattern of cortisol, glycemia, glycemia:insulin ratio, and surface temperature were not affected by the treatment, the acrophases being at ∼06:00 h, ∼18:00 h, ∼08:00 h, and ∼11:00 h, respectively. The acrophase of insulin concentration was observed earlier in Treated than in Control rams (13:02 ± 0:56 vs 15:47 ± 0:53; P =0.04). Additionally, the acrophase of the time spent eating was advanced in Treated rams (09:48 ± 00:16 vs 10:20 ± 00:16; P =0.04) and sleeping (21:39 ± 00:57 vs 02:02 ± 01:06; P <0.0001). Treated rams slept less time than Control rams (P =0.04). In conclusion, the administration of eCG modulated the daily variation pattern of insulin concentration and the behavioral pattern (period in which rams were observed eating and sleeping). Nevertheless, although there was a greater cortisol concentration and reduced eye surface temperature, the administration of eCG did not modify their daily variation pattern, suggesting that this is robust, limiting the effect of testosterone on their basal pattern.

Heat stress response in slick vs normal-haired Criollo Limonero heifers in a tropical environment

To assess the effect of hair type on the heat stress response, 20 Criollo Limonero heifers with slick (n = 11) or normal hair (n = 9) were studied. Under a high temperature-humidity index (THI) environment, heat stress response was assessed through physiological variables that included respiration rate (RR), heart rate (HR), ruminal frequency (RMF), rectal temperature (RT), saliva pH (SPH), and lymphocyte count (LC) in the morning (5:00 AM, 27.4 °C, 64% relative humidity, THI = 77) and afternoon (1:00 PM, 34.5 °C, 70% relative humidity, THI = 88). A case-control study using a split plot design was used. Data were analyzed using ANOVA (PROC MIXED SAS 2010) and a statistical model comprising the fixed effects of hair length, sampling hour, interaction of hair length by sampling hour, and the random effect of animal nested within hair type on physiological variables associated with heat stress response. Sampling hour influenced (P < 0.0001) RR, RT, and (P < 0.003) SPH. Hair length influenced RR (P < 0.01) and RT (P < 0.04) and tended to influence LC (P < 0.07). The interaction of sampling hour by hair influenced RR (P < 0.04), RT (P < 0.0002), and both SPH and LC (P < 0.05). During afternoon hours, slick-haired heifers had lower values for RR (81 ± 4.2 vs 102 ± 4.7 bpm; P < 0.01), RT (39.5 ± 0.1 vs 40.3 ± 0.1 C°; P < 0.002), and LC (60 ± 3.2 vs 72.3 ± 3.6; P < 0.09) than normal-haired heifers. In normal-haired heifers, SPH increased during afternoon compared to morning-hours (8.66 ± 0.1 vs 9.11 ± 0.1; P < 0.04). It was concluded that slick-coated heifers exhibited an enhanced capability to cope with heat stress compared to normal-haired heifers likely due to an enhanced capacity for heat dissipation.

Ambiente físico y respuestas fisiológicas de ovinos bajo sombra en horas de máxima radiación

Con el objeto de describir la relación entre las variables climáticas y las respuestas fisiológicas, 20 ovejas fueron asignadas a: Con Sombra (CS): sombra artificial (12:00 - 14:00 h) en corral con techo de malla sombra (70%); Sin Sombra (SS): sin ofrecimiento de sombra. Se determinó radiación solar (RS; W/m2), temperatura ambiental (°C), humedad relativa (%), temperatura de globo negro (TGN; °C) e índice de temperatura-humedad (ITH; unidades), temperatura superficial (TS; °C; termómetro infrarrojo), temperatura corporal (TC; °C; termómetro digital), frecuencia respiratoria (FR; mov/min; observación directa) y coeficiente de tolerancia al calor (CTC; unidades) (PROC MIXED; SAS).Adicionalmente, los datos fueron analizados por componentes principales (InfoStat/E, 2008).CS presenta una menor TS (35,9) en comparación con SS (38,9; P ≤ 0,01); igual ocurre en TC (P ≤ 0,01). La FR en CS (112,3) fue superior a SS (139,6; P ≤ 0,01). El CTC fue mayor en SS (7,8) vs. CS (5,8; P ≤ 0,01), indicando mejor bienestar térmico en CS. La TS en lomo, cadera y/o costado presenta alta relación con TC. TGN > 42,8 y de RS > 529,1 podrían indicar reducciones del bienestar térmico. Basado en la TC y FR, el punto de quiebre del ITH en ovinos es > 80.

Confort térmico y crecimiento de corderas West African pastoreando con y sin acceso a sombra artificial

Con la finalidad de evaluar el efecto de la presencia o no de sombra durante el pastoreo sobre el crecimiento y confort térmico de corderas mestizas West African, se realizó un estudio utilizando 24 hembras ovinas de 13,08 ± 3,0 kg de peso vivo, las cuales fueron distribuidas al azar en dos tratamientos: SOMBRA: pastoreo en potrero de pasto estrella (Cynodon nlemfluensis) con acceso voluntario a sombra artificial o techo de lona de 36 m2 (3 m2 por animal) y SOL: pastoreo en potrero de pasto estrella sin disponibilidad de sombra natural o artificial. La experiencia se realizó en el Laboratorio-Sección Ovinos de la Facultad de Agronomía - Universidad Central de Venezuela. Los animales se encontraban pastoreando en dos potreros de pasto estrella durante 6 semanas. Las mediciones realizadas fueron: mediciones climáticas tomadas con dos estaciones meteorológicas portátiles (una para cada potrero y la de sombra colocada debajo del techo) que registraban temperatura ambiente (TA, °C), humedad relativa (HR, %) y radiación solar (RS, w/m2), con estas mediciones se estimó el índice de temperatura y humedad o ITH. Temperatura corporal (°C) y frecuencia respiratoria, para estimar el coeficiente de tolerancia al calor (CTC). El crecimiento de las corderas fue evaluado a través de las mediciones: peso vivo (PV), ganancia diaria de peso (GDP), largo corporal (LC), perímetro torácico (PT), altura a la cruz (AC), con las cuales se estimaron los índices de masa corporal 1 (IMC1) e índice de masa corporal 2 (IMC2). En cuanto a las variables climáticas, la TAmax y HR promedio resultaron mayores para SOMBRA que para SOL, en 1,3 °C y 8,1 %, respectivamente (p