Estrés por calor en ganado lechero con énfasis en la producción de leche y los hábitos de consumo de alimento y agua. Revisión

The negative impact of heat stress (HS) in dairy cattle results in considerable economic losses at world level, as it reduces the milk production, reproductive efficiency, and productive life in the cows. In addition, the continuous genetic improvement results in highly productive cows, which are, however, less tolerant to HS because they produce greater metabolic heat. This, together with global warming, will turn HS into a hard-to-control challenge for the daily industry. In response dependent on the degree of HS, the dairy cattle carry out a series of physiological, metabolic and behavioral adjustments as thermoregulatory mechanisms for removing excess body heat and reducing the endogenous production of body heat, in order to maintain the normothermia. However, fertility and milk secretion decrease as a direct effect of hyperthermia and an indirect effect of lower dietary nutrient intake. Food and water intake are closely associated to the reduction of the productivity of dairy cattle exposed to HS. Notably, the impact of HS on productivity of dairy cattle varies among breeds, among which Bos taurus, particularly the Holstein breed, are less tolerant to HS. The identification of genes associated to thermotolerance utilized in selection programs using genetic markers to breed high milk-producing cows in warm climates is currently being studied. Therefore, the purpose of this review is to carry out a comprehensive analysis of the effects of HS on milk production, activation of thermoregulatory mechanisms and feed intake behavior in dairy cattle.El impacto negativo del estrés por calor (EC) en la ganadería lechera repercute en cuantiosas pérdidas económicas a nivel mundial, dado que reduce la producción de leche, la eficiencia reproductiva y la vida productiva de las vacas. Adicionalmente, el mejoramiento genético continuo resulta en vacas muy productivas, pero menos tolerantes al EC debido a que producen mayor calor metabólico. Esto en conjunto con el calentamiento global convertirá al EC en un reto difícil de controlar para la industria lechera. Como respuesta dependiente del grado de EC, el ganado lechero realiza una serie de ajustes fisiológicos, metabólicos y conductuales como mecanismos de termorregulación para disipar el exceso de calor corporal y reducir la producción endógena del mismo, todo dirigido a mantener la normotermia. Sin embargo, la secreción láctea y la fertilidad se reducen por efecto directo de la hipertermia e indirectamente por la reducción en el consumo de nutrientes dietéticos. Los consumos de alimento y de agua están asociados estrechamente con la reducción de la productividad en ganado lechero expuesto a EC. Cabe mencionar que el impacto del EC en la productividad del ganado lechero varía entre razas, siendo las razas Bos taurus menos tolerantes al EC, particularmente la raza Holstein. Actualmente, se investiga en la identificación de genes asociados con la termotolerancia, los cuales son empleados en programas de selección por marcadores genéticos para producir vacas altas productoras de leche en climas cálidos. Por lo tanto, el objetivo de esta revisión es hacer un análisis comprensivo de los efectos del EC sobre la producción de leche, activación de mecanismos de termorregulación y conducta de ingesta en ganado lechero

Prevalence and risk factors for stillbirths in Holstein cows in a hot environment

Risk factors for stillbirth were studied in a dairy operation in northern Mexico (25°N). Data set consisted of 29406 full term calving records. Factors affecting stillbirths were analyzed using a step-wise multivariable logistic regression models. The predictive indicators of stillbirth risk were: temperature-humidity index (THI) during pregnancy and at calving, season of calving, calf birth weight, gestation length, semen characteristics (conventional or sexed), gender of calves, hour of calving and type of parturition (normal or dystocic). Throughout the study period, 7.3 (95%, confidence interval= 7.0–7.6) of every 100 calving events had a stillborn calf. Stillborns were higher with severe dystocia compared with non-assisted births (29.0% vs. 6.2%, p<0.0001) and calves with birth weights <35 kg compared with heavier calves at calving (19.3% vs. 2.3%, p<0.0001), and was lower in calves whose gestation length was >278 d compared with calves with shorter gestation periods (2.8% vs. 30.0%, p<0.0001). Cows in a severe state of heat stress prenatally and at birth (THI >83 units) had 1.3 higher risk of stillbirths than cows suffering reduced heat stress (p<0.0001). Evidence for a greater (p<0.001) stillbirth rates in cows with parturitions between 18:00 and 19:00 h compared with cows calving during other hours of the day was found (9.1% vs. 7.1%). Together, these results demonstrate that ameliorating heat stress during the peripartum period is an important management practice to reduce stillbirths in Holstein cows in this warm climate. Additionally, a greater attention of parturition around sunset can lower the current stillbirth rates

Usporedba djelovanja korionskog gonadotropina konja (eCG) i estradiol cipionata primijenjenih 24 sata nakon prestanka kontrolirane primjene progesterona kao dijela protokola za sinkronizaciju estrusa i umjetno osjemenjivanje meksičkog Criollo goveda.

Two experiments were conducted to evaluate the effect of administering equine chorionic gonadotropin (eCG) in substitution of estradiol, 24 h after the removal of a progesterone intravaginal device, on estrus and ovulatory response, and pregnancy rates of Rodeo Criollo cows (exp. 1, n = 21) and heifers (exp. 2, n = 39) subjected to a synchronization protocol (estradiol + CIDR + PGF2α) with estrus-detected artificial insemination. All females were inseminated 12 h after detected estrus. In cows, estrus and ovulation response, and maximum pre-ovulatory follicle diameter were similar (P>0.05) between equine chorionic gonadotropin and estradiol groups. However, the time to estrus was shorter (P0.05) in ovulation rate. Both treatments resulted in low pregnancy rates, with a significantly lower (P0,05) u skupinama krava kod kojih je bio primijenjen korionski gonadrotropin ili estradiol. Međutim, u skupini kod koje je bio primijenjen estradiol vrijeme do estrusa je bilo kraće (P0,05) u stopi ovulacije. Oba su postupka dovela do niže stope gravidnosti, pri čemu je smanjenje kod junica kojima je bio primijenjen korionski gonadotropin konja bilo signifikantno (P<0,05). Zaključno, primjena korionskog gonadotropina konja, kao zamjene za estradiol nakon uklanjanja sredstva za otpuštanje progesterona, dovela je u sklopu protokola za otkrivanje estrusa i umjetno osjemenjivanje do povećanog grupiranja estrusa i ovulacije te posljedično veće stope gravidnosti u krava, ali ne i u junica

Effect of climate and insemination technique on reproductive performance of gilts and sows in a subtropical zone of Mexico

The objective of this study was to analyse the reproductive performance of hybrid (Yorkshire x Landrace) gilts/sows in relation to temperature-humidity index (THI) at artificial insemination (AI), season of AI, occurrence of estrus &gt;8 d post-weaning, repeated estrus, insemination technique (cervical, CAI or post-cervical, PCAI) and parity. Data included 8851 reproductive records (1771 for gilts and 7080 for sows) from a pig farm in a sub-tropical zone (THI ranged from 72.9 in January to 81.8 in June). A decrease in pregnancy rate (PR, 89.8 vs 93.0%; P&lt;0.01) and a tendency to decline farrowing rate (FR, 87.9 vs 90.3%; P=0.07) following AI during high THI (&gt;82), compared to AI at &lt;74 THI were observed. The spring and summer season were associated with decreased (P&lt;0.01) PR compared with fall and winter (90.0% vs 93.0%). Likewise, FR decreased in spring and summer compared to fall and winter (88.5% vs. 90.9%). FR was higher (P&lt;0.01) in non-repeat breeders compared with that of repeat-breeders (90.3% vs 76.2%). Litter size increased (P&lt;0.01) from 10.8 ± 3.2 to 11.1 ± 3.1 pigs when the interval from weaning to estrus was &gt;8 d. The insemination technique did not affect PR and FR but the litter size decreased (P&lt;0.05) from 11.3 ± 3.0 to 11.1 ± 2.9 pigs when PCAI was used compared to CAI. This study reaffirms the negative effects of the hot season on reproductive performance of gilts/sows, although thermal stress at AI did not cause foetal losses. Also, there is no advantage in using the PCAI as compared to the CAI in gilts/sows with high numbers of sperm cells per AI

Vaccination programs, parity, and calving season as factors affecting the risk of fetal losses and mummified fetuses in Holstein cows

Aim of the study: To investigate vaccination programs, parity, and calving season as factors affecting the risk of abortion and mummified fetuses in Holstein cows.Area of study: Hot zone of Northeast Mexico.Material and methods: Multiple logistic regression models were used to examine the relationship between peripartum disorders, parity, previous occurrence of abortion, season of calving, vaccination program, incidence of abortion, and mummified fetuses in Holstein cows.Main results: For 7014 pregnancies (2886 cows), the percentage of cows aborting and having mummified fetuses was 17.7% and 1.1%, respectively. As the number of brucellosis vaccinations increased, the incidence of abortion increased (10.4% for a single vaccination and 38.0% for 6 accumulated vaccinations). Abortion for cows having 1-2 previous abortions (56%) and &gt;2 abortions (77%) was fivefold and sevenfold greater (p&lt;0.01), respectively, than that for cows without previous abortion. Other important risk factors for abortion were number of calvings (19.8% for nulliparous and primiparous vs. 13.8% for &gt;3 parturitions; OR=1.7, p&lt;0.01), leptospirosis vaccine application &lt;55 days postpartum (dpp; OR=1.3, p&lt;0.05), viral vaccine application &gt;37 dpp (OR=1.3, p&lt;0.01), brucellosis vaccine application &gt;20 dpp (OR=1.6, p&lt;0.01), and no application of clostridial vaccine (OR=3.7, p&lt;0.01). Significant risk factors for mummified fetuses were application of ≥3 brucellosis vaccinations (OR=3.3, p&lt;0.01), no application of 10-way clostridial vaccine (OR=2.3, p&lt;0.01), &gt;2 previous abortions (OR=18.4, p&lt;0.01), and calving in autumn (OR=0.4, compared to winter, p&lt;0.05).Research highlights: Risk of abortion and mummified fetuses in Holstein cows has been found to be related to vaccination programs

Efectividad del clorhidrato de zilpaterol en la finalización de corderos: Patente vs. Genérico

The objective of this study was to compare the effect of the patent vs. generic sources of zilpaterol hydrochloride (ZH) on the productive performance, carcass characteristics, primary cut yields, and meat quality of lambs finished in feedlot. Thirty (30) Dorper×Pelibuey male lambs were distributed into 10 blocks, each with three lambs of similar initial live weight which were randomly assigned to the following treatments: 1) without ZH (control), 2) with patent ZH (PZH), and 3) with generic ZH (GZH). Treatment means were compared through two orthogonal contrasts: control vs. ZH (PZH+GZH) and PZH vs. GZH. ZH did not affect (P≥0.15) the productive performance, carcass weight, backfat thickness, or fat percentages (kidney-pelvic-heart, mesenteric or omental), but increased (P≤0.05) Longissimus dorsi muscle area and yields of carcass, shoulder, leg, and plain loin. As for the meat quality, ZH did not affect (P≥0.24) pH and shear force, but reduced (P<0.05) redness, yellowness, and chroma color values at 24 h post mortem, as well as the redness value (P<0.01) at 14 days of aging. With exception of carcass yield which tended (P=0.07) to increase with PZH, all measured variables were similar (P³0.14) between PZH and GZH. It has been concluded that both types of ZH at a dose of 0.10 mg per kg of live weight promote muscular hypertrophy in finishing lambs; however, this dosage is not sufficient to result in a better productive performance or carcass weight.El objetivo del estudio fue comparar el efecto de la fuente del clorhidrato de zilpaterol (CZ;  patente vs genérico) sobre el comportamiento productivo, características de la canal, rendimientos de cortes primarios y calidad de la carne de corderos finalizados en corral. Se distribuyeron 30 corderos Dorper ×Pelibuey en 10 bloques donde cada bloque tenía tres corderos de similar peso vivo inicial, los cuales se asignaron aleatoriamente a los siguientes tratamientos: 1) sin CZ (testigo), 2) con CZ de patente (CZP), y 3) con CZ genérico (CZG). Las medias de tratamientos se compararon a través de dos contrastes ortogonales: testigo vs. CZ (CZP+CZG) y CZP vs. CZG. El CZ no afectó (P≥0.15) el comportamiento productivo, peso de la canal, espesor de grasa dorsal, ni los porcentajes de grasa (riñón-corazón-pelvis, mesentérica u omental), pero aumentó (P≤0.05) el área del músculo Longissimus dorsi y los rendimientos de canal, paleta, pierna y lomo plano. En calidad de la carne, el CZ no afectó (P≥0.24) el pH y esfuerzo al corte, pero redujo (P<0.05) los valores de color rojizo, amarillento y chroma a las 24 h post mortem, y también los valores de rojizo (P<0.01) a los 14 días de maduración. Con excepción del rendimiento en canal que tendió (P=0.07) a ser mayor con CZP, todas las variables medidas fueron similares (P³0.14) entre CZP y CZG. Se concluye que ambos tipos de CZ a una dosis de 0.10 mg/kg de peso vivo promueven hipertrofia muscular en corderos de finalización, pero no es suficiente para reflejarse en mejor comportamiento productivo y peso de la canal

Efecto de la adición de clorhidrato de zilpaterol genérico en el perfil bioquímico y hematológico de ovinos de pelo engordados en corral

This study aimed to evaluate zilpaterol hydrochloride (ZH, generic) supplementation on fattening hair sheep, using hematological and biochemical variables as health status indicators. A total of 32 hair lambs (Dorper x Pelibuey) were grouped by initial weight and randomly assigned into four treatments: T1= basal diet (control group), T2= basal diet supplemented with ZH at 0.10 mg·kg-1 of LW d-1 (Grofactor®, Virbac México, Guadalajara, Mexico), T3= basal diet supplemented with ZH at 0.20 mg·kg-1 of LW d-1, and T4= basal diet supplemented with ZH at 0.30 mg·kg-1 of LW d-1. Blood samples were collected on days 1, 15, and 30 of the study. The hematological profile was determined in fresh blood samples; metabolites, electrolytes, and hormones were determined in serum samples. The study followed a randomized complete block experimental design, using an orthogonal polynomial analysis to determine the trend of the responses at the different concentrations of ZH. Cholesterol and urea levels were higher (P<0.05) in T3 than in T2. Furthermore, the mean corpuscular hemoglobin concentration was higher (P<0.05) in T1 than in T3; the red blood cell distribution width was higher (P<0.05) in T2 and T3 than in T4. The Na levels and the number of platelets showed a linear trend (P <0.05) to decrease and increase, respectively, as ZH levels increased. A quadratic trend was observed (P<0.05) in mean corpuscular hemoglobin concentration and red blood cell distribution width with increasing dose of ZH (generic). The remaining variables did not show significant trends at ZH levels (generic). The values of the biochemical and hematological profiles were within the reference range, which suggests that the addition of ZH did not alter the health status of fattening lambs. El objetivo fue evaluar la adición de clorhidrato de zilpaterol (CZ, genérico) en la dieta de ovinos de pelo de engorda, sobre variables hematológicas y bioquímicas como indicadores del estado de salud. Treinta y dos (32) corderos de pelo cruzados (Dorper x Pelibuey) se bloquearon por peso inicial y cuatro tratamientos y se asignaron aleatoriamente dentro de cada bloque: T1= dieta basal (grupo testigo), T2= dieta basal más 0.10 mg·kg-1 de PV d-1 de CZ (Grofactor®, Virbac México, Guadalajara, México), T3= dieta basal más 0.20 mg·kg-1 de PV d-1 de CZ y T4= dieta basal más 0.30 mg·kg-1 de PV d-1 de CZ. Se tomaron muestras de sangre los días 1, 15 y 30 del estudio. El perfil hematológico se estimó en muestras de sangre fresca, mientras que metabolitos, electrolitos y hormonas en muestras de suero. El diseño experimental fue bloques completos al azar y se efectuó análisis de polinomios ortogonales para determinar la tendencia de las respuestas a los niveles de CZ. Los niveles de colesterol y urea fueron mayores (P<0.05) en T3 que en T2; asimismo, el nivel de concentración corpuscular medio de hemoglobina fue mayor (P<0.05) en T1 que en T3, mientras que el ancho de distribución de eritrocitos fue mayor (P<0.05) en T2 y T3 que en T4. Los niveles de Na y el número de plaquetas mostraron tendencia lineal (P<0.05) a disminuir y aumentar, respectivamente, conforme los niveles de CZ aumentaron. Se observó tendencia cuadrática (P<0.05) en la concentración corpuscular media de hemoglobina y ancho de distribución de eritrocitos al aumentar la dosis de CZ (genérico). Las variables restantes no mostraron tendencias significativas a los niveles de CZ (genérico). Los valores de los perfiles bioquímico y hematológico se encontraron dentro del rango de referencia, lo que sugiere que la adición de CZ no alteró el estado de salud de corderos en engorda

Actividad antihelmíntica in vivo de hojas de Acacia cochliacantha sobre Haemonchus contortus en cabritos Boer

This study aimed to evaluate the effect of supplementing the maintenance diet of Boer goat kids with Acacia cochliacantha leaves. The endpoints evaluated were Haemonchus contortus fecal egg count (FEC) and water and dry matter intake. Two experimental treatments were evaluated on ten recently weaned goat kids (16.850 ± 1.630 kg of initial live weight and three months of age) experimentally infested with H. contortus larvae (L3) (350 larvae per live weight kilogram). Treatment 1 (T1) served as the control and consisted of infested animals without diet supplementation with A. cochliacantha leaves. Treatment 2 (T2) consisted of infested animals fed diets supplemented with 5% of A. cochliacantha leaves. Animals were grouped from highest to lowest based on their FEC. The two animals groups with the highest values were randomly assigned to T1 or T2; this was repeated until completing five repetitions per treatment. The evaluated variables were: FEC (per gram of feces), water intake, and dry matter intake (DMI). The results show that goat kids fed diets with 5% of A. cochliacantha leaves have lower (P 0.05). Se concluye que la adición de hojas de A. cochliacantha en dietas para cabritos tienen actividad antihelmíntica, por lo que esta leguminosa arbórea podría representar una opción en el manejo integral de la nematodiasis de cabritos Boer en crecimiento

Impacto del estrés por calor en la producción de ovinos de pelo. Revisión

Frente al problema del calentamiento global y cambio climático, los pequeños rumiantes serán clave para mantener la producción de proteína de origen animal, ya que tienen superioridad en la tolerancia al calor en comparación con otros animales domésticos. Los ovinos de pelo han demostrado ampliamente su habilidad para crecer y reproducirse en escenarios naturales de altas temperaturas y baja disponibilidad de nutrientes. La adaptación que presentan estos ovinos al estrés calórico está dada por una compleja interacción entre los mecanismos de termorregulación y la presencia de factores genéticos, lo cual les confiere una plasticidad fisiológica para tolerar climas calientes sin afectar drásticamente la productividad. Bajo condiciones de México, los ovinos de pelo se encuentran distribuidos en los diferentes climas debido a que no presentan una estacionalidad reproductiva, y esta característica permite a la industria ovina mantener una producción de carne constante a través del año; sin embargo, poca atención se ha puesto sobre su habilidad para producir en condiciones de estrés calórico. En este sentido, la presente revisión tiene como objetivo hacer una descripción de los efectos del estrés calórico sobre el comportamiento reproductivo, el crecimiento de corderos y la termorregulación de ovinos de pelo.