F. D. Álvarez-Valenzuela

Effects of zilpaterol hydrochloride on growth performance, carcass characteristics, and wholesale cut yield of hair-breed ewe lambs consuming feedlot diets under moderate environmental conditions.

Twenty-four Dorper × Pelibuey ewe lambs initially weighing 25.1 ± 0.6 kg were used in a 34-d feeding experiment and after slaughter to evaluate the effect of zilpaterol hydrochloride (ZH) on feedlot performance, carcass characteristics, and wholesale cut yield. Ewe lambs were individually housed in pens, blocked by initial BW, and assigned randomly within BW blocks to 1 of 2 treatments: 1) control (no ZH) and 2) supplemented with ZH (10 mg/ewe lamb daily) during 32-d and a 2-d withdrawal preslaughter period. Feeding ZH increased (P < 0.01) final BW, ADG, and G:F of ewe lambs, whereas feed intake was unaffected (P = 0.80). Hot and cold carcass weights, dressing percentage, and conformation score were improved (P < 0.001) when ZH was fed. Likewise, LM area was 3.7 ± 0.41 cm(2) larger (P < 0.001) for ZH than control ewe lambs. Feeding ZH did not affect (P ≥ 0.29) cooling loss, carcass length, fat thickness, or KPH. With exception of peritoneum (P < 0.001), head (P = 0.021), and neck (P < 0.001), ZH did not increase (P ≥ 0.12) noncarcass components or wholesale cut yield percentage. A trend to increase (P = 0.060) loin percentage from HCW was observed in lambs supplemented with ZH. In conclusion, feeding ZH to Dorper × Pelibuey ewe lambs improved feedlot performance and also some carcass traits (HCW, cool carcass weight, dressing percentage, and LM area) of economic importance; however, fat deposition was not affected by ZH.

Crecimiento y características de canal en corderos Pelibuey puros y cruzados F1 con razas Dorper y Katahdin en confinamiento.

The aim of this study was to evaluate feedlot performance and carcass characteristics of 36 male and female lambs from the genotypes pure Pelibuey, Dorper x ...

Pelibuey Ewe Productivity and Subsequent Pre-weaning Lamb Performance Using Hair-sheep Breeds Under a Confinement System

Abstract Macías-Cruz, U., Álvarez-Valenzuela, F.D., Correa-Calderón, A., Molina-Ramírez, L., González-Reyna, A., Soto-Navarro, S. and Avendaño-Reyes, L. 2009. Pelibuey ewe productivity and subsequent pre-weaning lamb performance using hair-sheep breeds under a confinement system. J. Appl. Anim. Res., 36: 255–260. The purpose of this study was to evaluate the effect of hair sheep sires on reproductive performance of Pelibuey ewes and to compare pre-weaning growth traits of their offspring. Forty-three Pelibuey ewes were randomly distributed in 3 groups to be mated by 3 breed sires (Dorper, Dr; Katahdin, Ka and Pelibuey, Pb). Fertility, fecundity and prolificacy were similar (P>0.05) among the three breed sires. In ewes mated to Dr, gestation length was 1.8 and 3.3 d shorter (P<0.01) than those mated to Ka or Pb sires, respectively. Birth weight, weaning weight and average daily gain up to weaning were higher among single born Ka lambs. Weaning litter weight per ewe lambing was greater (P<0.04) in ewes mated to Dr and Ka sires. In conclusion, Pelibuey ewes under a confinement system crossed with Dr or Ka sires improved their reproductive efficiency; moreover, pre-weaning traits of their lambs were also improved.

Thermoregulation of nutrient-restricted hair ewes subjected to heat stress during late pregnancy.

In summers with severe hot environmental temperatures, thermoregulation is expected to be critical during the last third of gestation of hair ewes, and this effect can be overstated by suboptimal feeding conditions. Twenty-four multiparous hair sheep ewes with approximately 100d of pregnancy were randomly assigned to two treatments to evaluate the effects of nutritional restriction (NR) during late gestation on some serum metabolites, physiological variables, and thyroid hormone concentrations under intense heat load (maximum temperature 42-45°C). Treatments were as follows: (1) control, ewes fed free choice wheat straw plus a concentrate at a rate of 500g/d, and (2) nutritionally-restricted (NR) ewes, which were offered wheat straw only ad libitum. Body weight of NR ewes dropped 5.1kg (P<0.05), while control ewes gained 4.7kg during the study period. Rectal temperature was not affected (P>0.05) by feeding regime either in the morning or afternoon hours. Respiration rate was greater (P<0.05) in control ewes (20 and 40breaths/min higher in the day and night, respectively) on d 130 and 145 of pregnancy compared to NR ewes. Skin temperatures during the morning and afternoon were affected (P<0.05) by feeding regime at d 130 and 145 of pregnancy. In the morning, NR ewes presented greater (P<0.05) head and rump temperature at day 145 of gestation, and lower (P<0.05) udder temperatures at d 130 and 145 than control ewes. In the afternoon, skin temperatures of NR ewes were higher (P<0.05) in head and right flank on d 130 and 145 of pregnancy, and in udder at day 145 compared to control ewes. Serum glucose was higher (P<0.05) in NR ewes than control animals at day 145 of pregnancy. Serum cholesterol, triglyceride and thyroid hormones were not affected by nutritional restriction. Overall, it was found that nutritionally restricted ewes were less affected by intense heat loads than well-fed ewes, apparently due to the lower metabolic heat produced by this underfed animals. Also, it was apparent that the lower respiration rate of NR ewes was compensated by a greater body surface temperature.

Ovejas Pelibuey sincronizadas con progestágenos y apareadas con machos de razas Dorper y Katahdin bajo condiciones estabuladas: producción de la oveja y crecimiento de los corderos durante el período predestete

Resumen es: El objetivo de este estudio fue evaluar la productividad de 253 ovejas Pelibuey (Pb) paridas entre el 2005 y 2008, las cuales fueron apareadas con ma...

Effect of zilpaterol hydrochloride on feedlot performance, nutrient intake, and digestibility in hair-breed sheep.

Twelve Dorper × Pelibuey wether lambs (26.8 ± 1.6 kg initial BW, 5 mo of age) were used to evaluate effects of zilpaterol hydrochloride (ZH) on feedlot performance, and effects of ZH and ZH supplementation period (15 and 30 d) on nutrient intake and digestibility. Lambs were blocked by initial BW, and assigned randomly within BW blocks to 1 of 2 treatments: i) control (no ZH), and ii) supplemented with ZH (10 mg ZH/wether lamb daily). Measurements of intake and digestibility were performed on d 9 to 15 and 24 to 30. Feedlot performance data were analyzed as a randomized complete block design, and nutrient intake and digestibility data were analyzed as a randomized complete block design with a 2 × 2 factorial arrangement of treatments. Final BW, ADG, total BW gain, and G:F were greater (P ≤ 0.04) for ZH than for control lambs. No treatment × feeding duration interaction for nutrient intake and apparent total tract digestibility were observed (P > 0.05). Intake of DM, OM, CP, and GE were less (P ≤ 0.03) for ZH than for control. Lambs fed for 30 d had greater (P ≤ 0.04) NDF and GE intake compared with those fed for 15 d. Total tract digestibility of DM, OM, CP, EE, and ADF (P ≤ 0.03) was less for ZH than control. Furthermore, calculated DE, ME, and TDN intake decreased (P < 0.01) with ZH supplementation. Also, DM, CP, and ether extract(EE) digestibility were greater (P < 0.01) for 30 d than for 15 d. Additionally, greater (P ≤ 0.01) DE, ME, and TDN intake was observed for 30 d compared with 15 d. In conclusion, ZH supplementation of wether lambs consuming feedlot diets resulted in improved feedlot performance and reduced the intake and digestibility of some nutrients.

Buffel grass (Cenchrus ciliaria L.) substitution for orange pulp on intake, digestibility, and performance of hairsheep lambs

Twenty Dorper x Pelibuey male lambs were used to evaluate the effect of substitution of forage with fresh orange pulp (FOP) in diets for fattening lambs on productive behavior, nutrient intake, apparent digestibility coefficient, and feeding costs. Lambs were divided into five groups (n = 4) and then housed in individual pens during 70 d. Treatments consisted of five levels of FOP (0, 25, 50, 75 and 100%) which substituted buffel grass hay on the base diet (40:60%, forage:concentrate). Additionally, changes in chemical composition of FOP stored in stack during 8 d were evaluated (from the day 1 until day 8). Daily feed intake expressed as kg/day and % live weight, lamb growth rate, feeding cost of each lamb per day and per fattening period, hemicellulose intake, and DM, OM, CP, NDF and hemicellulose digestibility showed a quadratic effect (P < 0.05), while DM, OM and CP intake presented a cubic effect (P < 0.05) with the increasing level of FOP. The maximum estimated value for those variables was observed at 75% of hay replacement with FOP. With respect to changes in chemical composition of pulp stored, DM content increased (P = 0.0011) from 210 to 310 g/kg FOP and OM, fiber fraction, and ash content were constant (P > 0.05) among storage days. Therefore, replacing around 75% of buffel grass hay with FOP in diets for fattening lambs resulted in the best growth rate and more efficient diet utilization. Fresh orange pulp stored in a stack did not change its chemical composition, and did not affect its utilization as a sheep feedstuff.

Evaluation of the efficacy of Grofactor, a beta-adrenergic agonist based on zilpaterol hydrochloride, using feedlot finishing bulls.

Beta-adrenergic agonists (β-AA) have been shown to positively impact finishing performance and some carcass traits of feedlot cattle. Our objective was to evaluate the efficacy of a β-AA on the basis of zilpaterol hydrochloride (Grofactor, Laboratorios Virbac México, Guadalajara, Mexico) on growth and DMI, carcass characteristics, and meat quality of finishing bulls. Forty-five bulls (75% 25% ) initially weighing 448.7 ± 2.58 kg were blocked by BW and randomly assigned to 1 of 3 diets, using pens of 3 animals, in a randomized complete block design: 1) daily feeding without β-AA in the basal diet (Control), 2) daily feeding with 0.15 mg/kg BW of Grofactor added to the basal diet (ZHG), or 3) daily feeding with 0.15 mg/kg BW of Zilmax (MSD Salud Animal México, Mexico City, Mexico) added to the basal diet (ZHZ). The duration of the feeding period was 30 d with a subsequent 4-d withdrawal period. Compared with Control bulls, the group fed ZHG had a 12% better ( < 0.025) G:F ratio, and their final BW ( 0.094) and ADG ( 0.084) tended to be enhanced. Feedlot performance of ZHG and ZHZ bulls was similar, although the DMI was ∼4% lower ( 0.05) in ZHG bulls vs. the ZHZ and Control groups. The HCW ( 0.001) and dressing percentage ( 0.015) were higher by 20 kg and 3%, respectively, in ZHG bulls vs. Control bulls. The KPH fat was lower ( 0.007) in bulls fed ZHG than in nonsupplemented bulls, but other carcass characteristics were not different in the ZHG and ZHZ bulls, and noncarcass components were not affected by ZHG or ZHZ supplementation. At 48 h postmortem, ZHG bulls had lower ( 0.007) water holding capacity and trended toward ( 0.06) increased chroma and reduced pH ( 0.09) compared to Control bulls. However, compared to ZHZ bulls, ZHG bulls had higher ( 0.02) chroma and a trend ( 0.08) toward increased hue angle. At 14 d postmortem, meat quality variables did not differ between the 3 groups of bulls. Supplementation of ZH Grofactor improved feedlot performance and some carcass characteristics of finishing bulls without affecting meat quality. The effects of Grofactor on feedlot performance, carcass traits, and meat quality were similar to those of Zilmax.

Efecto de época del año (verano vs. invierno) en variables fisiológicas, producción de leche y capacidad antioxidante de vacas Holstein en una zona árida del noroeste de México

El estres por calor (EC) induce la produccion de radicales libres derivados del oxigeno que se asocian con efectos negativos en la fisiologia, patologia y productividad de vacas lecheras. Con el proposito de medir y comparar variables fisiologicas y productivas de vacas Holstein en verano e invierno en una zona arida, se seleccionaron aleatoriamente 40 vacas lactantes (100 a 150 d en leche) en un mes representativo de cada epoca del ano (n = 20/ epoca). Los datos fueron analizados en un ANOVA bajo un diseno experimental completamente al azar, con epoca del ano como factor de interes (verano vs. invierno), y un nivel de significacion del 5%. Las temperaturas de la piel en costado derecho, nalga, ubre y cabeza, asi como de la leche, fueron 10 oC mas altas (P < 0,05) en verano. La tasa respiratoria fue dos veces mayor (106,87 ± 0,05 vs. 47,74 ± 0,06; P < 0,05) en verano, mientras que la temperatura rectal alcanzo 1,6 oC mas (P < 0,05) en verano. Las concentraciones de colesterol y TAS fueron menores (P < 0,05) en verano, mientras que la glucosa, TOS and IEO fueron mayores (P < 0,05) en la misma epoca. La produccion de leche se redujo en mas del 50% (P < 0,05) en verano, observandose reducciones de 42,6% en la produccion de energia en leche y de 48,4% en la produccion de leche ajustada a 3,5% de grasa. Se concluye que el efecto del EC es evidente y tiene un efecto perjudicial en la fisiologia y productividad de vacas Holstein en produccion, lo que hace necesario utilizar innovaciones ambientales para reducir este impacto negativo de las altas temperaturas

Effect of short-term cooling on physiological and productive responses of primiparous Holstein cows exposed to elevated ambient temperatures

Abstract To evaluate effects of short periods of cooling on physiological and productive parameters during summer, 27 first parity cows were grouped into control, 1 h cooling (C); 2 h cooling (AM); and 4 h cooling (AM+PM). The cooling system consisted of misting and forced ventilation. Skin temperatures were lower (P<0.05) in the AM+PM group during the morning but higher (P<0.01) in the afternoon, compared to C and AM groups. The respiratory rate was lower (P<0.01) in the AM+PM group than in C and AM groups. Rectal temperature, milk production, milk protein, and milk energy output were similar among the groups. Conversely, milk fat was higher (P<0.05) in AM+PM cows. Because use of a 4 h cooling period enhanced some physiological parameters and milk fat in primiparous Holstein cows, we recommend increasing the cooling period in arid regions to achieve higher performance and comfort of dairy cows.