A variable growth rate modification of von Bertalanffy's equation for aquaculture

In aquaculture experiments of only a few months'duration, fish can approach their asymptotic size and growth rates may change greatly. One objective of aquaculture is to obtain a maximum economic return, and a growth model is needed to relate rate of growth to food consumption and other costs to find the optimum duration of growth cycles. Von Bertalanffy's equation is an asymptotic growth model which can be used for this purpose. A variable growth rate model was developed to describe fish growth oscillations observed in aquaculture experiments. This growth model provides improved estimates of von Bertalanffy's equation in aquaculture and can be used for an efficient evaluation of fish production during production cycles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73180/1/j.1365-2109.1994.tb00689.x.pd

Typology of rainfall fields to improve rainfall estimation in the Sahel by the area threshold method

The stratification of rainfall fields to improve specific rainfall models is a subject that has received relatively little attention in the literature. It is shown here that objective classification techniques, based on the intensities and spatial distribution of the rainfall fields, can produce meaningful results in terms of the area threshold method (ATM) model and climatology. Four approaches for rainfall classification, using rain gauge data, are proposed in order to improve the average areal rainfall estimation in the Sahel by the ATM model. Two of them are based on the structural behavior of the rainy area (area where it rains above a given threshold) function against a threshold. Based on this function, a new parameter, called the under profile area (UPA), has been proposed for the classification of rainfall fields. The groups obtained from the method based on this parameter are characterized by different average spatial structures. A significant improvement on the ATM model is observed by considering classification based on the UPA parameter. An average reduction of 34 % of the root-mean-square error is observed in a validation term. This improvement is a direct consequence of the fact that the optimal thresholds are different from one group to another, which is an important point when considering the impact of classification on the ATM model. (Résumé d'auteur

Chemical composition, palatability and physical characteristics of venison from farmed deer

The quality of venison from farmed deer were evaluated based on chemical composition, palatability scores, W-B shear force, ultimate pH, and color. The samples of venison were derived from javan rusa (Cervus timorensis russa), moluccan rusa (Cervus timorensis moluccensis), sambar (Cervus unicolor brookei), fallow (Dama dama) and imported red deer (Cervus elaphus). Moluccan rusa and red deer were fed grass. Javan rusa, sambar and fallow deer were fed concentrate. The venison obtained from grazing deer (grass-fed) gave higher moisture content (75.3%) than concentrate-fed or confinement-raised deer (74.4%) and imported venison (70.62%). Fat content in venison shows some differences between muscles and species. The concentrate-fed animals had a higher (P 0.05) palatability scores than grass-fed venison. Feeding regimens (grass-fed vs. concentrate-fed) significantly (P < 0.05) influenced fat composition in the venison of farmed deer in this study

Evolution of the peripheral blood lymphocyte populations in multiparous rabbit does with two reproductive management rhythms

The emergence of epizootic rabbit enteropathy is leading to changes in weaning protocols in commercial rabbitries. Traditional weaning protocols are being replaced with late weaning, beyond 35 days postpartum (dpp). The main objectives of this study were to compare the peripheral blood lymphocyte populations of multiparous rabbit does under two reproductive rhythms (insemination at 11 dpp and weaning at 28 dpp, insemination at 25 dpp and weaning at 42 dpp), and to assess the influence on those of kits. Samples of peripheral blood were taken in 22 adult females and 44 of their kits at different critical times, and several lymphocytic populations were evaluated by flow cytometry. Additionally, the perirenal fat thickness of does was also measured at partum and weaning to observe if body condition correlates with lymphocyte populations. During whole lactation, counts of total, CD5 +, CD4 + and CD8 + lymphocytes of females were generally lower with weaning at 42 dpp compared to 28 dpp. Moreover, counts of total, B and CD5 + lymphocytes in rabbit does weaned at 42 dpp correlated to their body condition (+0.60 to 0.82; P<0.05), contrary to that observed in rabbit does weaned at 28 dpp. Some correlations between lymphocyte counts in both groups of does and weaning rabbits were observed. At weaning, those young rabbits weaned at 42 dpp had a significantly lower number of CD4 + lymphocytes than those weaned at 28 dpp (P<0.01). In conclusion, the 42 ddp rabbit does presented a lower number of total lymphocytes and lymphocytic subpopulations during lactation and at weaning, as well as lesser capacity of adjustment during the gestation-lactation cycle. © 2010 Elsevier B.V.This study has been supported by grants from the CEU-Cardenal Herrera University (Banco Santander/CEU-UCH: Copernicus Program (PRCEU-UCH/COOP 01/08), Generalitat Valenciana (ACOMP/2009/207 and ACOMP/2010/062) and the Comision Interministerial de Ciencia y Tecnologia (AGL2008-00273/GAN). Grants for Selena Ferrian and Irene Guerrero from Generalitat Valenciana (the Santiago Grisolia programme) and from the CEU-Cardenal Herrera University, respectively, are gratefully acknowledged.Guerrero, I.; Ferrian, S.; Blas Ferrer, E.; Pascual Amorós, JJ.; Cano, JL.; Corpa, JM. (2011). Evolution of the peripheral blood lymphocyte populations in multiparous rabbit does with two reproductive management rhythms. Veterinary Immunology and Immunopathology. 140(1-2):75-81. https://doi.org/10.1016/j.vetimm.2010.11.017S75811401-

How selection for reproduction or foundation for longevity could have affected blood lymphocyte populations of rabbit does under conventional and heat stress conditions

[EN] The present work characterises how selection for reproduction (by comparing two generations - 16th and 36th - of the V line selected for litter size at weaning) or foundation for reproductive longevity (the LP line) can affect the blood lymphocytes populations of reproductive rabbit does under normal [conventional housing, average daily minimum and maximum temperatures of 14 degrees C and 20 degrees C, respectively] and heat stress conditions [climatic chamber, 25 degrees C and 36 degrees C] from the first to the second parturition. Housing under heat stress conditions significantly reduced the B lymphocytes counts in female rabbits (-34 x 10(6)/L; P < 0.05). The highest lymphocytes population value in blood (total, T CD5(+), CD4(+) and CD8(+)) was noted at the first parturition, while the B lymphocytes count was significantly lower at the second parturition (-61 x 10(6)/L; P < 0.05). Selection for litter size at weaning (V females) reduced the average counts of total and B lymphocytes in blood (-502 and -60 x 10(6)/L, respectively; P < 0.01), mainly because these populations in V36 females continuously lowered from the first to the second parturition under normal housing conditions. Thus, more selected females (V36) at the second parturition showed significantly lower counts in blood for total, T CD5(+) and CD25(+) lymphocytes (-1303, -446 and -33 x 10(6)/L, respectively; P < 0.05). The main differences in blood counts between V36 and V16 females disappeared when housed under heat stress conditions, except for T CD5(+) and CD25(+), which significantly increased (T CD5(+): +428 x 10(6)/L; CD25(+): +41 x 10(6)/L; P < 0.01) in the V16 vs. V36 females on day 10 post-partum. Under normal conditions, no differences between LP and V36 females were found for most lymphocyte populations; only higher counts were noted in CD25(+) (+20 x 10(6)/L; P < 0.05) for LP females. However, the lymphocytes counts [especially total (+1327 x 10(6)/L; P < 0.01) and T CD5(+) (+376 x 10(6)/L; P < 0.10)] of LP females increased under heat vs. normal conditions when lymphocytes populations presented the lowest values (second parturition), while V36 females' counts remained invariable. Positive correlations were found between feed intake (r = +0.51; P < 0.001) and females' perirenal fat thickness (r = +0.40; P < 0.001) with B lymphocytes counts in the blood of primiparous rabbit females in the week 2 of lactation. These results indicate that selection for litter size at weaning might diminish their immune system's response and adaptation capacity, while the foundation for reproductive longevity criteria leads to more robust rabbit females as they present greater modulation under heat stress conditions when the immune system is affected. (c) 2012 Elsevier B.V. All rights reserved.This study has been supported by grants from the CEU-Cardenal Herrera University (Banco Santander/CEU-UCH: Copernicus Program), Generalitat Valenciana (ACOMP/2009/207 and ACOMP/2010/062) and the Comision Interministerial de Ciencia y Tecnologia (AGL2008-00273/GAN, AGL2008-03274/GAN and AGL2011-30170-CO2-02). Grants for Selena Ferrian and Irene Guerrero from Generalitat Valenciana (the Santiago Grisolia programme) and from the Universidad CEU-Cardenal Herrera, respectively, are also gratefully acknowledged.Ferrian, S.; Guerrero, I.; Blas Ferrer, E.; García Diego, FJ.; Viana, D.; Pascual Amorós, JJ.; Corpa, JM. (2012). How selection for reproduction or foundation for longevity could have affected blood lymphocyte populations of rabbit does under conventional and heat stress conditions. Veterinary Immunology and Immunopathology. 150(1-2):53-60. doi:10.1016/j.vetimm.2012.08.007S53601501-

A semi-quantitative RT-PCR method to measure the in vivo effect of dietary conjugated linoleic acid on porcine muscle PPAR gene expression

Conjugated linoleic acid (CLA) can activate (in vitro) the nuclear transcription factors known as the peroxisome proliferators activated receptors (PPAR). CLA was fed at 11 g CLA/kg of feed for 45d to castrated male pigs (barrows) to better understand long term effects of PPAR activation in vivo. The barrows fed CLA had lean muscle increased by 3.5% and overall fat reduced by 9.2% but intramuscular fat (IMF %) was increased by 14% (P < 0.05). To measure the effect of long term feeding of CLA on porcine muscle gene expression, a semi-quantitative RT-PCR method was developed using cDNA normalized against the housekeeping genes cyclophilin and β-actin. This method does not require radioactivity or expensive PCR instruments with real-time fluorescent detection. PPARγ and the PPAR responsive gene AFABP but not PPARα were significantly increased (P < 0.05) in the CLA fed pig’s muscle. PPARα and PPARγ were also quantitatively tested for large differences in gene expression by western blot analysis but no significant difference was detected at this level. Although large differences in gene expression of the PPAR transcriptional factors could not be confirmed by western blotting techniques. The increased expression of AFABP gene, which is responsive to PPAR transcriptional factors, confirmed that dietary CLA can induce a detectable increase in basal PPAR transcriptional activity in the live animal

Phosphorus characterization in feces from broiler chicks fed low-phytate barley diets

The inclusion of low phytate grains in poultry diets can reduce the phosphorus (P) content of poultry feces, but their influence on fecal P composition is not well established. To assess this, 100 male broiler chicks (21 days old) were fed dietary treatments based on either a wild-type barley or one of three low phytate mutant barleys with 59, 62 and 99% reductions in phytate P, compared with the normal barley diet. The birds were housed in raised-floor battery cages with mesh grate floors above fecal collection trays with five birds per pen and five pens per treatment. The birds were fed for 9 days and feces were collected twice a day during the last 2 days of the experiment. Total P concentrations were 14-24% lower in feces from birds fed low phytate barley diets compared with those fed the normal barley diet. Phosphorus digestibility increased (P < 0.05) as phytate in the barley diet decreased. Phosphate was the major P fraction in the feces (69-75% extracted P) regardless of the type of barley fed. Phytate constituted only 3-12% of the P in the feces, indicating its hydrolysis in the bird. Overall, these results suggest that feeding low-phytate barley diets can reduce P concentrations in poultry feces without causing significant changes in P composition