ABSTRACT The objective of this study was to evaluate the effects of four levels of fish oil on lamb performance, carcass yield, ruminal fermentation, and leptin gene expression in perirenal fat. Thirty-two lambs (24.10±2.15 kg, Katahdin × Pelibuey) were used in a completely randomized experimental design. The lambs were assigned to one of four dietary treatments (n = 8 lambs/treatment), expressed as g/kg DM basis: 0 fish oil and 300 corn; 10 fish oil and 250 corn; 20 fish oil and 205 corn; and 30 fish oil and 170 corn. The lambs were weighed on consecutive days at the beginning (days 0 and 1) and at the end (days 55 and 56) of the trial. Ruminal fluid samples were collected on day 56 to evaluate the ruminal fermentation pattern. The lambs were slaughtered on day 56; perirenal adipose tissue samples were collected and the carcass yields were recorded. Volatile fatty acids, ammonia N, and leptin mRNA expression were not affected by the dietary treatments. However, the dry matter intake, average daily gain, final body weight, and the hot carcass yield showed either increased linear or quadratic responses as the proportion of fish oil increased in the ration; the estimated optimal level obtained of fish oil levels for average daily gain was 11.2±0.21 g/kg and 12.8±4.67 g/kg for feed conversion. Additionally, feed efficiency and backfat thickness had an increment, showing quadratic response as the proportion of fish oil increased in the diet. Increasing the fish oil concentration in the diet does not affect leptin messenger ribonucleic acid expression. The lamb performance can be improved with 12 g/kg fish oil in diets of finishing lambs.

Para obtener los parámetros reproductivos de la iguana verde (Iguana iguana) criada en condiciones de cautiverio, se utilizaron 71 hembras (669,1 g) y 17 machos ( 652,2 g), con edad de 1,5 a 7,5 años, las cuales se alojaron en jaulas de 5 x 6 m, donde se observó y registró la actividad reproductiva durante tres años, considerando como variable independiente la edad de los reproductores. Se utilizó estadística descriptiva. El peso de las hembras fue diferente (P<0,01) de acuerdo con la edad. La proporción hembras machos fue mayor (P<0,01) en las hembras de mayor edad. El periodo de celo, gravidez y mortalidad de las hembras fueron similares (P>0,05) a cualquier edad. El peso de nidada, número total de huevos, peso y ancho de huevo fueron diferentes (P<0,01), mientras que la longitud de los huevos fue similar (P>0,05) en todas las posturas estudiadas. El éxito de eclosión de los huevos y porcentaje de supervivencia fueron semejantes (P>0,05); no obstante, la masa relativa de nidada fue diferente (P<0,05). Se concluye que en las hembras de la Iguana iguana mantenidas en cautiverio, es posible escoger como posibles reproductores, a aquellas que presentan un rango de 4,5 a 7,5 años de edad, ya que presentan los mejores parámetros reproductivos.

The objective of this study was to obtain the reproductive parameters of the green iguana (Iguana iguana) in captivity. Seventy one females (669.1 g) and 17 males (652.2 g) were used. The ages of the iguanas were from 1.5 to 7.5 years old which were kept captivity in a 5 x 6 m cages, where the reproductive activities were observed and recorded over three years. Age was considered as an independent variable within the reproductive parameters. Descriptive statistic was determined. The weight of the females was different (P<0.01) according to age. The proportion of female:male intromission was greater (P<0.01) in older females. The periods of estrus, pregnancy and mortality of the females were similar (P>0.05) at all ages. The clutch weight, number of eggs, weight and width of eggs were different (P<0.01) for each female, whereas the length of eggs was similar (P>0.05) in all ovipositions. The successful hatching of the eggs and the enlivening the hatchlings were similar (P>0.05) for each female; however, the relative mass of each clutch was different (P<0.05). It was concluded that in female Iguana iguana raised in captivity, it is possible to select as potential reproductive individuals to those who have a range of 4.5 to 7.5 years of age, since they have the best reproductive parameters.

Se estudió la cinética de producción de gas in vitro para conocer el potencial nutricional de hojas de arbóreas y vainas que crecen en una zona tropical seca de México usando heces bovinas como inóculo, comparadas con el pasto guinea como referencia (Panicum maximum). Se colectaron hojas y vainas de: Prosopis laevigata, Pithecellobium dulce y Pithecellobium acatlense; y sólo hojas de: Amelanchier denticulata, Verbesiana crocata, Haemotoxylum brasiletto, Acacia bilimekii, Acacia pennatula, Acacia constricta y Lantana velutina. El inóculo se preparó con heces bovinas recién depuestas disueltas en agua en proporción 1:3. Se estimaron los parámetros de la velocidad máxima de producción de gas (v), la tasa de producción (s) y la fase lag (l). Tres especies mostraron bajos valores de gas (8,34-11,4 ml), mientras que la mayoría fueron cercanos a los del pasto guinea (29 ml) con una tasa de producción similar (0,03 h-1). Con excepción de la vaina de Pithecellobium acatlense, el resto tuvo mayor producción de gas (33,8-46,3 ml) que el pasto guinea (25,6 ml) con una tasa de producción igual o mayor (0,03 a 0,06 h-1). Los resultados indican que las vainas de Prosopis laevigata y Pithecellobium dulce tienen un valor nutricional superior al del pasto guinea mientras que las hojas de Haemotoxylum brasiletto y Prosopis laevigata presentaron un valor similar. La técnica de producción de gas in vitro permite estimar el valor potencial de recursos forrajeros no convencionales

The kinetics of in vitro gas production to achnowledge the nutritional potential of tree leaves and pods that grow in a dry tropical area of Mexico using bovine faeces as inoculum, compared with guinea grass (Panicum maximum) as reference was studied. Leaves and pods were collected from: Prosopis laevigata, Pithecellobium dulce and Pithecellobium acatlense; and only leaves from: Amelanchier denticulata, Verbesiana crocata, Haemotoxylum brasiletto, Acacia bilimekii, Acacia pennatula, Acacia constricta and Lantana velutina. The inoculums were prepared with fresh bovine faeces dissolved in water in 1:3 ratio. Parameters estimated were the maximum gas production (v), the production rate (s) and the lag phase (l). Three species showed low gas values (8,34-11,4 ml) while most were close to those of guinea grass (29 ml) with a similar production rate (0,03 h-1). In the pods, with exception of Pithecellobium acatlense, the others presented a higher gas production (33,8-46,3 ml) than guinea grass (25,6 ml) with a rate of production similar o greater (0,03 a 0,06 h-1). The results indicate that the pods of Prosopis laevigata and Pithecellobium dulce have nutritional value superior to that of guinea grass while leaves from Haemotoxylum brasiletto and Prosopis laevigata have a similar value. The gas production technique in vitro allows the estimation of the potential value of non-conventional feed resources