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Tres protocolos reproductivos fueron evaluados: 1) PG: inyección de PGF2α en el día 50 posparto e inseminación (IA) en base a detección del estro. 2) OVS (Ovsynch: día 0, GnRH; día 7, PGF2α; día 9, GnRH; día 10, IA); y 3) ROV (GnRH + Ovsynch: día- 7, GnRH; día 0, GnRH; día 7, PGF2α; día 9, GnRH; día 10, IA). Además, el efecto de la somatotropina (bST) a la IA, sobre la fertilidad al primer servicio posparto (FERT), y la tasa de preñez a 99 días posparto (PP). FERT fue similar en ROV y OVS (36.2 vs 36.6 %) (P>0.05); y mayor a PG (27.3 %) (P0.05). PG y sin bST (22.5 %) fue menor que OVS con (38.5 %), y sin bST (33.7 %); y que ROV con bST (37.0 %) y sin bST (36.1 %); y PG con bST (32.9 %) (P

Se estimó la tasa de pérdida de colonias de abejas melíferas (Apis mellifera) y los factores asociados en los inviernos 2016 al 2019 en la región centro-occidente de México. Se encuestaron 389 apicultores y 50,392 colonias fueron incluidas en el análisis. La tasa de pérdida de colonias fue del 23.61% para el invierno 2016-2017 (IC 95% 19.97-27.24%), de 15.43% para el invierno de 2017-2018 (IC 95% 13.35-17.51%) y de 25.33% en el invierno de 2018-2019 (IC 95% 23.0-27.65%). La tasa de pérdida de colonias en el invierno de 2017-2018 fue significativamente menor que la tasa de pérdida en los inviernos 2016-2017 y 2018-2019 (P

The aim of this study was to evaluate the effects of short-term supplementation of the beta-adrenergic agonist (β-AA) zilpaterol hydrochloride (ZH) along with progestin estrus synchronization on weight gain, estrous behavior, ovarian structures and reproductive performance of Rambouillet ewes. Thirty-one Rambouillet ewes (12–14 months old and 3.2 ± 0.2 body condition score in a scale of 1–5) were primed with intravaginal sponges (20 mg chronolone) for 14 days and injected with a single i.m. dose of 400 IU of eCG at sponge removal. Treatments consisted of 1) β-AA group (n = 15, ZH supplementation in diet at a dose of 0.15 mg/kg/d, from day 6 to day 2 before sponge removal), and 2) Control group (n = 16, general management without ZH supplementation). Weight gain, estrus behavior, reproductive performance and ovarian structures by transrectal ultrasonography were recorded. The number of matings per ewe and duration of standing estrus were greater (P

El objetivo del estudio fue determinar el efecto del sexo, tipo de parto, raza, condicion de crecimiento retardado y mes de nacimiento sobre peso al nacimiento (PN), crecimiento pre- y post-destete de crias ovinas de pelo nacidas en invierno (n=416). Los corderos mostraron mejor (P

The objective of this work was to determine the amitraz treatment effect against Varroa destructor on the population and food reserves of honeybee colonies, during the four seasons of the year in Mexico's central high plateau. 48 colonies with similar sister queens, homogeneous populations, food reserves, and Varroa infestation levels were used.12 colonies received acaricidal treatment in the summer, 12 in winter, 12 in summer and winter, and 12 were untreated. The Varroa infestation levels were determined in adult bees, worker brood, and by mites on the hives' floor for one year. The adult bee population, capped brood area, honey, pollen, and colony weight were also evaluated. There were statistical differences (P

The aim of this study was to determine the effects of landscape and collection period on yield and nutritive value of leaf litter from Quercus rugosa, and its potential use as sheep feed. Leaf litter collections were made at four periods during the defoliation season March and April 2013, in three different landscapes (canyon, hillocks or plateau). Biomass production, nutritive value and in vitro digestibility were estimated. In addition, the cafeteria technique was used to estimate the preference of Quercus rugosa leafs at inclusion levels of 10, 20, 30, 40, 50, 60 and 70% (Dry Matter basis) by sheep fed maintenance diets. The leaf litter biomass production was greater (P 0.05) among collection periods, but condensed tannins (CT) increased in (P

EnglishOne hundred eighty-nine Catalan crossbreed donkeys (Equus africanus asinus) were used to evaluate the effect of gender (gelding, n=106; or female, n=83) and live weight at slaughter (LW) (kg, n=37) on carcass characteristics, non-carcass components and meat and fat color. Geldings had greater (P151kg). Meanwhile, the LW did not affect the color (L*, a* and b* values) of subcutaneous fat (P>0.05). These results suggested that both gender and live weight should be considered when producing meat from donkeys. It is advisable to use geldings weighing more than 126kg at slaughter to obtain the greatest weight and carcass yield. Key words: carcass characteristics; donkey; gender; weight; meat portuguesO objetivo deste estudo foi avaliar o efeito do genero e peso vivo (PV) nas caracteristicas da carcaca, componentes nao-carcaca e cor da carne e gordura dos burros (Equus africanus asinus). Foram utilizados 189 animais de sexo castrado ou feminino. Os castrados tiveram peso de carcaca maior (P 151kg). Enquanto isso, o PV nao afetou a cor (valores de L *, a * e b *) de gordura subcutânea (P> 0,05). O peso maior da carcaca e o curativo com efeitos limitados em componentes nao carcaca, cor de carne e gordura foram observados em castrados com peso vivo superior a 126kg. Palavras-chave: caracteristicas da carcaca; burro; genero; peso; carne

This study evaluated whether the administration of 50 and 100mg bovine somatotropin (bST) at the start of synchronization and at the time of natural mating in ewes improves the ovulation rate, embryonic development and pregnancy rate of transferred embryos. Forty-eight donors were assigned to three treatments: the bST-100 treatment (n=15) received 100mg bST at the start of synchronization and at natural mating, the bST-50 treatment (n=15) received 50mg bST on the same schedule as the previous group, and the control (n=18) did not receive any bST. Two embryos were transferred to each recipient (n=121): 35 received embryos from bST-100; 50 received embryos from bST-50, and 36 received embryos from the control. The superovulatory rate, percentage of recovered structures, cleavage rate, percentage of transferable embryos, embryo quality and development and pregnancy rate were analyzed using the GENMOD procedure of SAS. The number of corpora lutea and the cell number were analyzed using the GLM procedure of SAS. The insulin and IGF-1 concentrations were analyzed with ANOVA for repeated measures. The bST application did not affect the superovulatory rate, number of corpora lutea and recovered structures (P>0.05). The numbers of transferable embryos and embryos reaching the blastocyst were higher (P≤0.01) in the bST-50 (96.4±3.6% and 69.0±7.8%) than the bST-100 (93.0±4.5% and 27.2±38.9%) and control (87.7±5.4% and 50.4±6.4%) groups. The insulin and IGF-1 concentrations were higher (P

The objectives of this study were to determine the chemical composition and dry matter digestibility of Quercus resinosa leaves harvested at different seasons of the year and to assess the intake and palatability of lamb diets containing foliage of Q. resinosa. There were three sites of collection, two located in the state of Jalisco and one in the state of Zacatecas, México. The young leaves harvested in spring, had greatest (P >0.05) nutritional value than leaves harvested in other seasons. The in vitro digestibility of organic matter (IVOMD), rapidly degradable fraction (a) and the degradation rate (c) were greater (P >0.05) in leaves harvested in spring and winter. The slowly degradable fraction (b) was greater (P >0.05) in spring, summer and autumn, and lesser in winter. The potential degradation fraction (a + b) and the effective degradability of dry matter were maximized (P >0.05) in spring than in the other seasons. The consumption was similar (P >0.05) among diets with different inclusion levels of leaves, but sheep consumed greater (P >0.05) amounts of diet containing leaves collected in spring. In conclusion, the Q. resinosa foliage contains the nutritional value and the digestibility and palatability that makes it suitable to replace completely the forage in the fattening diets of sheep, being preferable to use leaves harvested in spring and winter.

Zilpaterol hydrochloride (ZH) supplementation was evaluated on performance of growing goats for the last 42 days before slaughter. Forty-eight Anglo-Nubian × Criollo animals (12 per treatment) were randomly assigned to one of four treatments (ZH at daily doses of 0.0, 0.1, 0.2 or 0.3 mg/kg of BW in diet) in a complete block design. Basal diet contained 16.3% CP and 2.5 Mcal/kg ME. The ZH supplementation at doses of 0.1, 0.2 and 0.3 mg/kg of BW increased ADG by 22.1, 54.0 and 56.6%, and gain/feed ratio by 20.0, 40.0 and 60.0%, respectively. The DMI (g/kg of BW0.75) increased quadratically (P = 0.037). Carcass weight and dressing percentage (DP) augmented linearly (P ≤ 0.031) as level of ZH increased in diet. The ZH supplementation increased (P ≤ 0.023) longissimus muscle area (LM) and leg perimeter (LP) with a linear improvement (P 0.05) or trends (P > 0.10) were detected on purge loss (PL) or cooking loss (CKL). Growth differences between wether goats fed ZH doses of 0.2 or 0.3 mg/kg of BW were small, and therefore lower dose of 0.2 mg/kg of BW seems enough to enhance growth. Moreover, the carcass characteristics showed minor differences between levels of ZH supplementation, and therefore could be considered that the lower dose of 0.1 mg/kg of BW of ZH was sufficient to improve these traits. It is concluded that addition of ZH to diets of wether goats increased growth performance and carcass characteristics in a similar manner to that reported for cattle and sheep.

The aim of the study was to determine the effects of 3 feeding dose programs of the β-adrenergic agonists (β-AA) ractopamine hydrochloride (RH) or zilpaterol hydrochloride (ZH) for the final 30 d before slaughter on growth performance and carcass and meat characteristics of feedlot ram lambs. Eighty-four Dorper × Katahdin ram lambs (30.0 ± 1.6 kg) were blocked by BW and randomly assigned to pens (4 lambs per pen and 3 pens per treatment). Pens within a block were assigned randomly to 1 of 7 dietary treatments: 1) control (CTL) = diet without β-AA; 2) RH constant (RHC) = 20.0 mg/kg of RH, d 1 to 30; 3) RH increasing (RHI) = 10.0 mg/kg, d 1 to 10; 20.0 mg/kg, d 11 to 20; and 30.0 mg/kg, d 21 to 30; 4) RH decreasing (RHD) = 30.0 mg/kg, d 1 to 10; 20.0 mg/kg, d 11 to 20; and 10.0 mg/kg, d 21 to 30; 5) ZH constant (ZHC) = 6.0 mg/kg of ZH, d 1 to 30; 6) ZH increasing (ZHI) = 3.0 mg/kg, d 1 to 10; 6.0 mg/kg, d 11 to 20; and 9.0 mg/kg d 21 to 30; and 7) ZH decreasing (ZHD) = 9.0 mg/kg, d 1 to 10; 6.0 mg/kg, d 11 to 20; and 3.0 mg/kg, d 21 to 30. Overall, β-AA supplementation reduced DMI (P 0.05), with the exception of fat content that was reduced (P < 0.001) in lambs fed β-AA, and diameter of muscle fibers that was increased (P < 0.05) by ZHI treatment. Constant and increasing doses of ZH reduced (P < 0.05) the a* value of LM and semitendinosus muscles, with no effects on L* or b* values. The mass of liver was reduced (P < 0.05) in ZHI-treated lambs compared with CTL lambs, and plasma urea concentration was reduced (P < 0.05) by RH or ZH administration regardless of feeding program, although there were no other differences in organ mass weight (P ≥ 0.35) or blood metabolites (P ≥ 0.16). Increasing doses of RH or ZH augmented the growth performance response without negative effects on organ mass weight or blood metabolites. Although a ZHI program improved carcass characteristics, the increased LM fiber diameter of lambs fed ZHI program could be unfavorable because of the potential negative effect on tenderness.

Resumen es: Se evaluo la influencia de un macho cabrio sexualmente activo sobre el inicio de la actividad reproductiva (actividad hipotalamica y ovarica) y la sucesi...

Present study evaluated the presence of a sexually active male buck upon the influence of an estradiol implant in ovariectomised (OVX) goats exposed to a 6-month-long controlled photoperiod in a range of 13.4–10.6 light-hours per day. Mexican-native (Criollo) goats (n=20) were randomly assigned into 2 groups: (1) goats exposed to a sexually active male buck (n=10); (2) goats not exposed to a male buck (n=10). Each experimental group of goats included ovariectomised goats (OVX, n=5), and ovariectomised and estradiol-implanted goats (OVX + E2, n=5). Blood samples were taken from OVX and OVX + E2 goats, every four weeks, during 6 h at 15 min intervals (i.e., 24 samples/day). Frequency, amplitude, and concentration of luteinising hormone (LH) were determined. While the OVX + E2 goats depicted an increased LH pulse frequency (2.0±0.5 vs. 0.7±0.1), the presence of a sexually active male increased frequency, amplitude and concentration of LH in OVX goats compared to goats not exposed to males (frequency: 3.2±0.4...

Present study evaluated the presence of a sexually active male buck upon the onset of reproductive activity and estrous cycle progression in Criollo goats exposed to a 6-month long controlled photoperiod in a range of 13.4–10.6 light-hours per day. Mexican-native (Criollo) goats (n=10) were randomly assigned into 2 groups: (1) goats exposed to a male buck (n=5); (2) goats not exposed to a male buck (n=5). Blood samples were taken weekly to quantify serum-progesterone levels through radioimmunoanalysis. Male exposure increased luteal activity and estrous cycle progression reflected as a higher number of days in luteal activity (44±9.05 vs. 32.3±20.6); a reduced number of days in anestrous (4.0±4.8 vs. 51.9±28) and a greater number of luteal phases (15.7±4.4 vs. 11.3±8.7) without compromising serum progesterone levels (6.8±0.8 vs. 7.3±0.5). In conclusion, presence of a sexually active male induced a greater ovarian activity in Criollo goats, shortening seasonal anestrous irrespective of the controlled photo...

One hundred and twelve Dorper × Katahdin lambs (initial BW = 28.9 ± 0.9 kg) were used in a randomized complete block design, with the objective of evaluating the effects of feed supplementation with the β-adrenergic agonists (β-AA) ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) for the last 14, 28, or 42 d of feeding period, on growth performance and carcass characteristics of finishing lambs. Treatments consisted of the supplementation of 20.0 mg RH/kg of dietary DM or 6.0 mg ZH/kg of dietary DM for the last 14, 28, or 42 d of the feeding period, and a control group (without β-AA). Compared with controls, lambs fed β-AA, had greater ( P P = 0.04) linearly, but this tendency was vanishing ( P = 0.30) when DMI was expressed on BW or metabolic weight basis. Lambs fed β-AA had greater ( P ≤ 0.009) HCW, dressing percent, LM area, and reduced fat thickness when compared to lambs fed the control diet. Lambs fed ZH had greater HCW (3.9%, P = 0.001), dressing percentage (3.8%, P P = 0.006) than RH group. As the duration of ZH feeding increased, HCW and dressing percentage decreased ( P = 0.001), and fat thickness increased linearly ( P = 0.064); however, the lambs fed RH showed a linear increase ( P P ≥ 0.142) carcass traits. The proportion of leaner carcasses were increased ( P 2 , but these proportions were reduced linearly ( P ≤ 0.002) as the feeding duration became longer. β-AA supplementation increased growth performance in lambs as results of greater muscle accretion and body fat reduction. The β2-AA compound has a greater response in feedlot lambs than the β1-AA compound. Carcasses showed a more desirable combination of carcass characteristics if lambs were fed ZH during 42 d, and if lambs were fed RH between 28 and 42 d. Results of this study contribute to a better use of β-adrenergic agonists in feedlot lambs.

The effects of the β-adrenergic agonists ractopamine hydrochloride (RH; 0.35, 0.70 and 1.05 mg kg − 1 of BW d − 1 ) and zilpaterol hydrochloride (ZH; 0.10, 0.20 and 0.30 mg kg − 1 of BW d − 1 ) on growth performance and carcass characteristics were determined in 84 Dorper × Katahdin lambs (12 lambs per treatment), that were randomly assigned to a complete block design during a 42-day feeding trial. Lambs were fed a corn grain-based diet (18.71% CP and 12.9 MJ/kg ME). Nutrient digestibility of diets and blood serum metabolites were also determined. There were no significant ( P > 0.05) differences in growth characteristics by effect of ZH or RH administration. However, lambs final weight, total weight gain and ADG increased linearly ( P P longissimus muscle area, carcass conformation and quality grade, and improved quadratically ( P P > 0.01) fat thickness and improved ( P > 0.05) USDA yield grade and carcass quality grade. Both β-adrenergic agonists improved carcass characteristics; although greater improvements were obtained with ZH than RH for most carcass characteristics.

The study was conducted to evaluate and compare the effects of feed additives on ruminal fermentation, nutrient digestibility and performance of lambs fed diets containing 60% wet brewers grains (WBG). In Experiment 1, two simultaneous trials were conducted. Fifty intact (20.2±0.8 kg BW) lambs were used in a feedlot trial and 10 (rumen cannulated; 32±1 kg BW) in a digestion trial. The pH, volatile fatty acids (VFA) and ammonia-N in lambs were also estimated. Lambs were randomly assigned to one of five diets: i) without additives (Con), ii) with 1% bicarbonate (Bic), iii) with 1% bentonite (Ben), iv) with 33 mg/kg monensin (Mon) and v) with 200 mg/kg fibrolityc enzymes (Enz). In Experiment 2, 120 Rambouillet×Pelibuey intact male lambs (19.5±1.5 kg BW) were used in a feedlot trial and randomly assigned to four diets: i) without additives (control), ii) with 1% Bic, iii) with 33 mg/kg Mon and iv) with 1% Bic and 33 mg/kg Mon. In Experiment 1, lambs fed diets containing Bic or Mon had significantly higher final weight, DMI, ADG than other lambs. However, apparent DM, OM, CP, NDF and ADF digestibilities and ruminal individual VFA content were similar (p>0.05) among treatments. Conversely, treatment×collection period interaction was significant for ruminal pH and NH3. In Experiment 2, lambs fed diets containing a Bic and Mon combination had significantly higher final weight, DMI and ADG. It is concluded lambs fed

Aguilera-Soto, J.I., Ramirez, R.G., Arechiga, C.F., Mendez-Llorente, F., Lopez-Carlos, M.A., Silva-Ramos, J.M., Rincon-Delgado, R.M. and Duran-Roldan, F.M. 2008. Zilpaterol hydrochloride on performance and sperm quality of lambs fed wet brewers grain. J. Appl. Anim. Res., 34: 17–21. Forty Rambouillet × elibuey male lambs were grouped as light-weight (LW; n =20; 28±1.2 kg BW) and heavy-weight (HW; n = 20; 40.5±1.6 kg BW) to be fed a finishing diet containing 60% wet brewers grain with or without 6 mg kg1 DM ofβ-adrenergic agonist zilpaterol hydrochloride (ZH). On d 60 of the feeding trial, ZH was removed and semen collection was measured by electroejaculation. Further, on d 63 animals were slaughtered for carcass and meat quality evaluation. On d 15 of the feeding trial, lambs fed ZH gained significantly (about 25%) more weight. However, at the end of feeding trial (60 d period), ADG, DMI and feed efficiency were unaffected by ZH consumption. Sperm motility was significantly reduced by ZH only in ...

This study evaluated whether the administration of 50 and 100 mg bovine somatotropin (bST) at the start of estrous synchronization and at the time of artificial insemination improves lambing rate and prolificacy in hair sheep. Four hundred eighty adult hair ewes (Pelibuey, Blackbelly, Dorper, Katahdin, and their crosses) were synchronized with intravaginal sponge containing 40 mg of fluorogestone acetate. On the day of sponge insertion, ewes were assigned to three treatments: the bST-100 treatment (n = 156) received 100 mg bST at the start of synchronization (d 0) and at the time of insemination (d 14), the bST-50 treatment (n = 159) received 50 mg bST in the same schedule as the previous group, and the control (n = 165) did not receive any bST. Lambing rate and percentage of multiple births were analyzed using the GENMOD procedure of SAS. Prolificacy data were analyzed using the MIXED procedure of SAS. The IGF-1 and insulin concentrations were analyzed with ANOVA for repeated measures. The bST application did not affect the lambing rate (P = 0.06). The proportion of ewes with multiple births (P = 0.01) and prolificacy (P = 0.04) were higher in the bST-50 (54.3% and 1.57 ± 0.1) than the bST-100 (18.2% and 1.25 ± 0.1) and control (33.3% and 1.28 ± 0.1) groups. The IGF-1 and insulin concentrations were higher (P < 0.05) in the bST-treated groups, but the insulin concentration was higher (P = 0.001) in the bST-100 group than in the bST-50 group. The administration of 50 or 100 mg bST at the start of synchronization and at the time of artificial insemination does not increase lambing rate. However, the dose of 50 mg increased the proportion of multiple births and prolificacy.

Honey bee (Apis mellifera) colonies of African and European descent were compared for levels of Varroa destructor infestation in 3 different ecological regions in Mexico. The 300 colonies that were studied were located in subtropical, temperate sub-humid, and temperate dry climates. The morphotype and mitotype of adult bees as well as their rates of infestation by varroa mites were determined. Additionally, the number of combs with brood and covered with bees was recorded for each colony. The highest frequency of colonies that were classified as African-derived was found in the subtropical environment, whereas the lowest occurred in the temperate dry region. Overall, the colonies of African genotype had significantly lower mite infestation rates (3.5±0.34%) than the colonies of European genotype (4.7±0.49%) regardless of the region sampled. Significant effects of genotype and region on Varroa infestation rates were evident, and there were no differences in bee population or capped brood between genotypes. Mite infestation levels were significantly lower in the colonies of the temperate dry region than in the colonies of the other 2 regions. These results are discussed within the context of results from studies that were previously conducted in Brazil. This is the first study that demonstrates the effects of Africanization and ecological environment on V. destructor infestation rates in honey bee colonies in North America.

This study was conducted with the aim to evaluated biogas production from swine manure of fattening pig fed 0, 5, 10 or 15% of Opuntia robusta (dry matter basis). Sun dried swine manure was stored in 20-L containers during 45 d. Biogas production was measured for 4 days in 1-L digesters at 32 °C, 48 digesters were used (12 by treatment), every day the material of the collector bags was extracted and was consider biogas if that was flammable. Volume of flammable gas, flame time and burning temperature were recorded daily. During the experimental periods gas production was different (P

Aguilera-Soto J.I., Ramirez, R.G., Arechiga, C.F., Mendez-Llorente, F., Lopez-Carlos, M.A., Pina-Flores J.A., Medina-Flores C.A., Rodriguez-Frausto, H., Rodriguez-Tenorio, D. and Gutierrez-Banuelos, H. 2009. Effect of feed additives on digestibility and performance of Holstein cows fed wet brewers grains. J. Appl. Anim. Res. 36: 227–230. To evaluate different feed additives in cows fed wet brewer's grain, 5 ruminal-cannulated Holstein cows (470±45 kg; 18±3 kg d−1 milk), were allotted to a 5x5 Latin-square design. A total-mixed diet containing 33% wet brewers grains (WBG) was provided including: 1) no additives (Control), 2) 1% sodium bicarbonate, 3) 1% sodium bentonite, 4) 33 mg kg−1 sodium monensin and 5) 200 mg kgfibrolityc enzymes. Cows fed bicarbonate or enzymes had significantly higher dry matter intake (DMI). However, apparent digestibility of different nutrients did not differ (P>0.05) among dietary treatments. Similarly except acetate propionate ratio (A:P) none of the ruminal parameters ...

Aguilera-Soto, J.I., Ramirez, R.G., Arechiga, C.F., Gutierrez-Banuelos, H, Mendez-Llorente, F., Lopez-Carlos, M.A., Pina-Flores, J.A., Rodriguez-Frausto, H. and Rodriguez-Tenorio, D. 2009. Effect of fermentable liquid diets based on wet brewers grains on performance and carcass characteristics by growing pigs. J. Appl. Anim. Res., 36: 271–274. To evaluate growth and carcass characteristics of pigs fed graded levels of fermentable liquid diets (FLD) based on wet brewers grains (WBG), 32 Landrace × York male pigs (32±4 d; 9.7±1.2 kg) were allotted to one of the four treatment diets containing 0, 15, 30 and 45% WBG (dry matter basis). Animals were weighed every 20 d and dry matter intake (DMI) by pen was recorded daily. At 95 kg pigs were slaughtered and carcass characteristics were measured. Average daily gain of pigs was significantly different among treatments being higher for 0% WBG (660 g day−1) followed by 15% (553), 30% (537) and 45% (507), similar trend was observed for DMI (1895 g day−1, 18...