No abstract

Para determinar la influencia de la edad al corte en la composición química del ensilado de maíz blanco, se sembraron 36 parcelas (cuatro surcos; 8 m) con el híbrido de maíz blanco Asgrow-7573. En un diseño en bloques completos (DBCA) al azar con cuatro repeticiones, fueron asignadas a nueve fechas de corte: 103, 107, 111, 115, 119, 123, 127, 131 y 135 días a partir de la siembra. La planta se cortó 12 cm del suelo y fue picada a 3 cm; se prepararon mini-silos (5 kg) en bolsa de plástico y se les extrajo el aire. Los silos se abrieron después de 45 días y se les determinó materia seca, cenizas, proteína cruda, FDN, FDA y pH. A los resultados se les aplicó ANDEVA para un DBCA y análisis por polinomios. La materia seca del forraje verde y del ensilado, así como el pH aumentaron de manera lineal (P < 0.00001) a como se incrementó la edad al corte. La proteína cruda fue mayor (P < 0.05) en las primeras fechas. FDN y FDA mostraron un comportamiento cuadrático (P < 0.00001). Se concluye que el corte entre los días 123 y 127 favorece la composición química del ensilado de maíz blanco.

Heat stress induces failures in the physiological mechanisms that regulate the body temperature of farm animals and causes a loss in their productive and reproductive potential. Thus, we performed a scoping review to systematically map, describe, and classify primary research that assessed the effect of heat stress on the reproductive, physiological, and productive parameters of livestock. Electronic databases were searched to retrieve full-text, peer-reviewed experimental or cohort studies published from 1980 to August 2018. We included in vivo and in vitro studies exposing animals or cells to heat stress conditions and used a control group. Studies were evaluated based on title and abstract and then selected for final inclusion based on full text. We performed data charting to describe and visualize the evidence. In total, we included 466 studies, among which bovines and porcines were the most frequent species studied. Reproductive and physiological parameters were the main groups of outcomes assessed, and studies using adult females predominated. Seventy percent of the studies were experimental, and almost half of the studies used natural environmental conditions to assess the effect of heat stress in animals. Most of the studies were performed in the Americas and Asia, and three journals provided one-third of the publications. The systematic evidence synthesis presented herein outlines the trends of research performed to assess the effect of heat stress on livestock and allowed us to define future secondary studies to extend our knowledge about the negative impact of heat stress on the productivity of farm animals.

RESUMENPara determinar el efecto del nivel suplementario de extracto de taninos (ET) en la respuesta productiva de corderos en engorda, se realizó un experimento con un diseño de bloques completos al azar, en el que se usaron 48 corderos de pelo (3/4 Katahdin x 1/4 Pelibuey) con una edad promedio de 70 ± (desviación estándar) 5 d de edad DE y peso de 21.3 ± 3.23 kg DE durante un periodo de 70 días. Los tratamientos fueron: 1) Dieta formulada con grano de maíz, harina de soya y paja de maíz, con aporte nutrimental de acuerdo a la etapa fisiológica, sin adición de ET (testigo; n = 12); 2) dieta testigo más 0.15 % de ET (ET 15; n = 12); 3) dieta testigo más 0.30 % de ET (ET 30; n = 12) y 4) dieta testigo más 0.45 % de ET (ET 45; n = 12). Los resultados fueron analizados por ANDEVA (P ≤ 0.05), y la influencia del nivel de ET en la respuesta productiva se exploró mediante polinomios ortogonales. La ganancia diaria de peso (GDP) y la conversión alimenticia (CA) mejoraron (P ≤ 0.05) con la inclusión de 0.15 y 0.30 % de ET en la dieta, y el peso final fue mayor (P = 0.05) en los corderos que consumieron la dieta con 0.15 % de ET. Se observó una respuesta cuadrática (P ≤ 0.05) al nivel de adición de ET; el análisis de regresión sugiere que la mejor respuesta productiva puede obtenerse con niveles de 0.2 % de ET en la dieta (R 2 = 0.75; P < 0.01). Se concluye, que el consumo de dietas suplementadas con ET mejora la GDP y la CA, y la mejor respuesta se obtiene con 0.2 % de ET en la dieta. Palabras clave: Desempeño productivo, cordero, taninos. ABSTRACTTo determine the effect of supplementation tannin extract level (TE) on feedlot performance finishing hair lamb, was realized one experiment with a randomized complete block design, in that were used 48 hair lamb (3/4 Katahdin x 1/4 Pelibuey) with average 70 ± (standard deviation) 5 d old SD and an body weight of 21.3 ± 3.23 kg SD during a period of 70 day. The treatments were: 1) diet formulated with corn grain, soybean meal and corn straw, with nutritional support according physiology requirement, without addition of TE (Control; n = 12); 2) control diet plus supplementation with 0.15 % of TE (TE 15; n = 12); 3) control diet plus 0.3% of TE (TE 30; n = 12); and 4) control diet plus 0.45 % of TE (TE 45; n = 12). Results were analyzed by ANOVA (P ≤ 0.05), and the influence of TE level on productive response was explored using polynomial contrasts. Average daily gain (ADG) and feed conversion (feed/gain ratio) was improved (P ≤ 0.05) with the diet supplemented with 0.15 and 0.30% of TE, and body weight last was higher (P = 0.05) in the lamb feeding with supplemented diets 0.15% TE. Quadratic response was observed (P ≤ 0.05) to the TE supplementation level; the regression analyses suggest that better productive response may be found with TE 0.2% supplementation level (R 2 = 0.75; P < 0.01). It is concluded, that intake of supplemented diets

The porcine reproductive and respiratory syndrome (PRRS) is a viral disease that decreases the reproductive performance in breeding sows and leads to economic losses to the swine industry. The objective of the present study was to identify single nucleotide polymorphisms (SNP) associated to the number of live-born piglets in the first (LBP1) and second birth (LBP2) in breeding sows exposed to PRRS virus. The study included 100 pregnant females of the Landrace(¾)/ Yorkshire(¼) line, 75 of which were infected with the PRRS virus and 25 were free of PRRS. Individual blood samples (6-8 drops) were obtained and spotted onto FTA cards and subsequently processed for DNA extraction, which was genotyped using a 10,000 SNP chip for genomic profile. Resulting genotypes were analyzed using a multi-locus mixed model that detected three SNP associated to LBP1 and five SNP associated to LBP2 (P<0.001). These eight SNP were validated using an associative mixed effects model which included the terms genotype and age of dam as fixed effects, and sire as random effect. Allele substitution effects were estimated using the same model including the term genotype as covariate. The SNP rs81276080, rs81334603 and rs80947173 were associated to LBP1 (P<0.001), whereas the SNP rs81364943, rs80859829, rs80895640, rs80893794 and rs81245908 were associated to LBP2 (P<0.001). Only two SNP were in functional chromosomal regions and the remainder SNP were within an intergenic position. In conclusion, these results suggest the existence of gene variants associated with the reproductive performance of sows infected with the PRRS virus.