Enfriamiento al inicio de verano para mitigar el estrés por calor en vacas Holstein del noroeste de México

Abstract

RESUMENEl objetivo de este estudio fue determinar la respuesta fisiológica, endócrina y productiva en vacas lactantes sometidas a varias series de enfriamiento artificial al inicio de verano (junio a julio de 2011). Se asignaron 14 vacas Holstein multíparas a uno de dos tratamientos: enfriamiento (E) antes de la ordeña (0700 y 1700 h) y enfriamiento adicional (EA) cada 2 h de 0700 a 1700 h en el corral de espera a la ordeña. Se midió la producción de leche (PL), niveles de prolactina (PRL) e IGF1, mientras que la temperatura rectal y frecuencia respiratoria fueron registradas y consideradas como indicadores fisiológicos de estrés por calor. La temperatura ambiental y humedad relativa también fueron registradas y utilizadas para calcular el índice de temperatura-humedad (ITH). Los indicadores de estrés calórico mostraron una interacción significativa (P<0.001) entre tratamiento y tiempo/semana, los cuales fueron menores con EA (-3.8 respiraciones por minuto y -0.2 °C) sólo durante las semanas 6 y 7. Los niveles séricos de PRL fueron mayores bajo enfriamiento adicional (EA: 35.1 vs E: 29.4 ng/ml; P=0.004), mientras que los de IGF1 solo variaron a través de las semanas de muestreo (P=0.014). La PL se incrementó (P<0.05) en EA durante las semanas 6 (+3.1 kg/día) y 7 (+3.1 kg/día). Se concluye que la mayor frecuencia de baños mitigó la condición de estrés calórico al inicio de verano, permitiéndole a la vaca expresar un mejor desempeño productivo al final del estudio, ya que dicho efecto dependió de la variable tiempo/semana. PALABRAS CLAVE: Enfriamiento, IGF1, Producción, Prolactina. ABSTRACTThe objective of this study was to determine the physiological, endocrine and productive response in lactating dairy cows under several series of artificial cooling at the beginning of the summer (June to July, 2011). Fourteen multiparous Holstein cows were assigned in one of two treatments: Cooling (C) before milking (0700 and 1700 h) and additional cooling (AC) each 2 h (from 0700 to 1700h) in the holding pen of the milking parlor. Milk yield (MY), and serum levels of prolactin (PRL) and IGF1 were measured. Rectal temperature and respiratory rate were registered and included as physiological markers of heat stress. Ambient temperature and relative humidity were also collected and used to calculate temperature-humidity index (THI). Both markers of heat stress showed a significant interaction (P<0.001) between treatment and time/week, which were lower in AC treatment (-3.8 breaths per minute and -0.2 °C) during wk 6 and 7. Serum levels of PRL were higher under additional cooling (AC: 35.1 vs C: 29.4 ng/ml; P=0.004), while IGF1 serum levels showed variation only through the sampling weeks (P=0.014). The MY increased (P<0.05) in AC only during wk 6 (+3.1 kg/d) and 7 (+3.1 kg/d). It was concluded that additional cooling at the beginning of the summer reduced heat stress in dairy cows allowing a better productive performance at the end of the study because such effect relied on the variable time/week. 416José Clemente Leyva-Corona...

The Anti-Müllerian Hormone as Endocrine and Molecular Marker Associated with Reproductive Performance in Holstein Dairy Cows Exposed to Heat Stress

“…Therefore, only these four SNPs were further tested for validation as molecular markers via a genotype-to-phenotype association study. 1 SNP reference of the NCBI; 2 Gene symbol name; 3 F. Allele = allele with the favorable effect on phenotype; 4 Frequency of both alleles within cow population; 5 Hardy-Weinberg equilibrium "χ 2 " test value; 6 "χ 2 " test p-value with 1 degree of freedom and α = 0.05.…”

“…Several strategies have been reported to study the effects of HS on lactating cow fertility. The immediate strategy to reduce declines in fertility is to properly assess HS and provide a cooling program to dairy cows on the farm, regardless of their physiological stage [4]. Other short-and long-term management solutions to mitigate fertility declines during HS include the use of embryo transfer technology and timed artificial inseminations (TAI) from germplasm identified as thermo-tolerant with genome-assisted breeding values, lowering the rates of disease and mastitis, and feeding care.…”

“…SNP reference of the NCBI; 2 SNP chromosome variant;3 Bos taurus autosomal chromosome number;4 SNP position within the chromosome; 5 candidate gene symbol (LONRF1 = LON peptidase N-terminal domain and ring finger 1; AMH = Anti-mullerian hormone; IGFBP1 = insulin-like growth factor binding protein 1; TLR4 = Tolllike receptor 4; LGR5 = Leucine-rich repeat containing G protein-coupled receptor 5; SGO2 = Shugoshin 2; DISC1 = DISC1 scaffold protein; SLC39A10 = Solute carrier family 39 member 10; RSPH14 = Radial spoke head 14 homolog; CADM2 = Cell adhesion molecule 2) 6. alleles from the SNP; 7 percentage of trait variance explained by the SNP; 8 SNP statistical significance.…”

Disinfection of adult pecan leaflets Carya illinoinensis (Wangenh.) K. Koch. (Juglandaceae), and in vitro callogenesis induction

“…En la presente investigación, los foliolos desinfectados en agosto, fueron los más afectados por la presencia de contaminación fúngica. (Leyva Corona et al, 2015).…”