Thermal comfort and growth of West African lambs grazing with and without access to artificial shade [Confort térmico y crecimiento de corderas West African pastoreando con y sin acceso a sombra artificial]
Lopez R.,Central University of Venezuela |
Pinto-Santini L.,Central University of Venezuela |
Perozo D.,Central University of Venezuela |
Pineda J.,Central University of Venezuela |
And 4 more authors.
Archivos de Zootecnia | Year: 2015
In order to evaluate the effect of the presence or absence of shade during grazing on thermal comfort and growth of West African crossbred lambs, a study was carried out using 24 lambs 13.08 ± 3.0 kg live weight, randomly assigned to two treatments: SHADE: grazing star grass (Cynodon nlemfluensis) with voluntary access to artificial shade or shelter of 36 m2 (3 m2 per animal) and SUN: grazing star grass without availability of natural or artificial shade. The experiment was performed in the Sheep Unit of the Agronomy School – Universidad Central de Venezuela. The animals were grazing on two paddocks of star grass during 6 weeks. Climate measurements were take using two portable weather stations (one for each paddock and for SHADE was placed under the shelter), recording temperature (TA, °C) , relative humidity (HR, %) and solar radiation (RS, w/m2), also some indexes were estimated: index of temperature and humidity or ITH and the coefficient of heat tolerance or CTC. The growth of lambs was assessed through weekly measurements of body weight (BW), for the estimation of daily weight gain (GDP), body length (LC), chest circumference (PT) , wither height (AC) , through which the body mass index 1 (IMC1) and body mass index 2 (IMC2) were estimated. As results for climatic variables, TA and HR were higher for SHADE thanfor SUN, 1.3 °C and 8.1 %, respectively (p<0.01), perhaps due to the material used as a roof or shelter forming a microclimate under it that increased these variables. However, the shelter decreased approximately 90 % incidence of RS in shaded areas during daylight hours. As the ITH was superior to SHADE (73.5) than SUN (74.5), both values are associated with stress start. However, CTC values for animals grazing with SHADE were lower (p<0.01); 3.21 vs 3.51. Results also showed that the use of SHADE in the paddock did not affect the growth of the animals, since there was no effect of treatment on BW, GDP, LC, AC and IMC1 and IMC2. For PV the mean values were 14.59 and 15.10 kg; while for GDP were 80.8 and 82.6 g/d for SUN and SHADE, respectively. In conclusion, the presence of artificial shade with canvas roofs during the rainy season causes increased HR, generating stress conditions even in SHADE conditions. Also, the presence of SHADE in the paddock did not result in better growth of lambs, perhaps due to the short duration of the trial. © 2015, Universidad de Cordoba. All rights reserved.
Shadow effect at grazing on some physiological variables of West African lambs under emergency conditions of mild heat [Índices fisiológicos en corderas tipo West African con acceso voluntario a sombra artificial bajo condiciones de emergencia de calor leve]
Pinto-Santini L.,Central University of Venezuela |
Rios De Alvarez L.,Central University of Venezuela |
Oliveros I.,Campo universitario |
Pigliacampo A.,Central University of Venezuela |
Chacon T.,Central University of Venezuela
Livestock Research for Rural Development | Year: 2014
To evaluate the effect of the presence of artificial shade in pastures on some physiological indices in West African female lambs in emergency situations of mild heat (EMH), 24 animals (13.1 ± 3.0 kg and 3-3.5 months old) were randomly assigned to the following treatments: a) SHADOW (n = 12): voluntary access to artificial shade during the hours of grazing, and b) SUN (n = 12): without access to natural or artificial shade. Weather conditions were characterized by environment temperature (°C), relative humidity (%) and solar radiation (RS; W/m2). Additionally, were defined the experimental conditions with environmental conditions of severe heat emergency, EMH and no heat emergency. Every two week was evaluated breathing frequency (BF) (movements/min), cardiac frequency (CF) (heartbeat/min) and corporal temperature (CT) (°C).These variables were averages twice daily (AM: between 07:30 and 09:00 hours and PM: between 15:00 and 17:00 hours). In both treatments there were weather conditions considered EMH. There was a reduction of 92.6% in the RS in SHADOW. The most elevated RS in SUN occurred between 12:00 and 14:00 hours (13:00 hours = 608.5 W/m2). The BF was higher in SUN vs SHADOW (P <0.01) and an increase was observed in AM vs. PM (P <0.01). There was an increase of 0.2 °C in CT in SUN vs SHADOW during AM (P <0.05) and an increase of 0.5-0.7°C in PM vs AM. No effects attributable to treatment or time of measurement for CF were presented. Under conditions of ECL, the presence of artificial shade for voluntary access for grazing apparently mitigates climate effects in West African lambs in the tropics. © 2014, Fundacion CIPAV. All rights reserved.
Socio-economic aspects, administrative, technical and legal the blue crab fishery (Callinectes sapidus) en puerto concha, South lake Maracaibo [Aspectos socioeconómicos, administrativos, técnicos y legales de la pesquería del cangrejo azul (Callinectes sapidus) en puerto concha, Sur del lago de Maracaibo]
Molina M.,Campo universitario |
Mejias D.,Campo universitario |
Torres L.,Campo universitario |
Arvelo F.,Campo universitario |
Yarumare C.,Campo universitario
Agroalimentaria | Year: 2013
The aim of this study is to analyze the socio-economic, administrative, technical and legal aspects of the blue crab fishery at Puerto Concha (Zulia State, Venezuela). It was carried out with the fishermen of the Chamita Cooperative between 2010 and 2011. Data were collected by using a questionnaire and reviewing the record books. The fishermen are all experienced, with little formal education, high number of children, poor quality housing, and facing serious flaws in their basic services. The management of the fishery is limited to weigh the capture, to sell it wholesale, and to pay the staff. The audit of fisheries by the state is poor. Each fisherman collects Bs. 1,727.00 monthly, an income undoubtedly low, with no other economic benefits. It seems unlikely that crab fishing will become profitable in the coming years. The increased volume of fishing for the species forces the fishermen of Puerto Concha to move northward to make their catches, which implies increasing their efforts in man hours and cost of fishing. This makes the system increasingly unsustainable, with little impactr on improving their quality of life. In order to improve the profitability of the crab fishery it is suggested to change the frequency of catches becouse if fishing continues to be on a daily basis,fishermen will incur in higher costs, thereby reducing their net income margin.