The comparisons of non-linear models to describe the growth performance of Lori-Bakhtiari sheep.

BACKGROUND: The study of growth traits is of interest to many animal scientists, regardless of specialization, due to the economic importance of growth rate, mature weight and other related traits. OBJECTIVE: This study aimed to compare six non-linear models for describing the growth of Lori-Bakhtiari sheep. METHODS: In order to collect weight data, 85 lambs (41 males and 44 females) were reared from birth to 140 days of age, and their growth patterns were recorded by measuring their body weight at 10-day intervals. Various mathematical functions, including the negative exponential, Brody, Gompertz, Logistic, Morgan-Mercer-Flodin (MMF) and Weibull, were used to model the relationship between body weight records and age. RESULTS: The results showed that the MMF and Gompertz models provided the best fit to the body weight data, whereas the negative exponential model exhibited the worst fit. In all models, the asymptotic weight of male lambs was higher than females. The research also revealed differences in growth patterns between male and female lambs. Overall, females had a lower absolute growth rate than males, but they reached their peak growth at an earlier period, and their growth rate declined faster. CONCLUSIONS: The differences in growth patterns between males and females indicate the importance of analysing male and female data separately when describing growth. As a result, Gompertz model can be recommended to Lori-Bakhtiari female and male lamb breeders to determine more accurate growth traits. In addition, it should be considered that feeding male and female lambs separately according to absolute growth rate values may increase growth performance.

The ND1 and CYTB genes polymorphisms associated with in vitro early embryo development of Sanjabi sheep.

This study aimed to investigate the association between polymorphisms of ND1 and CYTB genes and in vitro early embryo development of Sanjabi sheep. Blood and ovarian samples were collected from a local slaughterhouse. The cumulus-oocyte complexes with a diameter greater than 3 mm were aspirated from follicles, and in vitro maturation (IVM) and in vitro culture (IVC) rates of them were recorded. A respective 1200 bp and 980 bp fragments of ND1 and CYTB genes were genotyped using a modified single strand conformation polymorphism (SSCP) method. The results of this study revealed that four different patterns, named as A, B, C, and D were observed for both ND1 and CYTB genes. The ND1 gene polymorphisms had significant effects on the IVM and IVC rate (p < 0.05). The pattern C of the ND1 gene significantly increased the IVM rate compared to the patterns A, B and D. For the IVC, the highest and lowest means were related to the C and B patterns, respectively. The CYTB gene polymorphisms also had significant effects on IVC (p < 0.01), but the IVM did not affected (p = 0.07). Here, the pattern D had the highest and the pattern C had the lowest means for both IVM and IVC rates.

Chromium Supplementation on the Growth Performance, Carcass Traits, Blood Constituents, and Immune Competence of Broiler Chickens Under Heat Stress: a Systematic Review and Dose-Response Meta-analysis.

Several studies have been conducted to assess the effects of supplemental dietary chromium (Cr) on broiler chickens under heat stress (HS) conditions, but the shape and strength of the associations between Cr supplementation and broiler chickens' responses to HS remain unclear. Therefore, the current systematic review and meta-analysis investigated the effectiveness and dose-response relationship of Cr. The results indicated non-linear dose-response associations between Cr supplementation and body mass gain (BMG), feed intake (FI), feed conversion ratio (FCR), carcass, breast, leg, and abdominal fat relative weight (Pnon-linearity < 0.05). The maximum BMG, FI, and the relative weight of carcass, breast, and leg would be achieved with 1200, 1100, 900, 800, and 800 ppb of Cr, respectively, while the lowest FCR and abdominal fat relative weight might be obtained with the supplementation of 1100 and 1000 ppb of Cr, compared with no Cr supplementation. Referring to BMG, supplementation with 1200-1700 ppb inorganic Cr or 2700 ppb or less organic Cr had a significant beneficial effect on the BMG, while NanoCr supplementation did not influence this outcome variable. A non-linear association was observed for blood total cholesterol concentration (TC, Pnon-linearity < 0.05), with the maximum reduction of TC concentration observed at approximately 900 ppb of Cr. The cholesterol-lowering effect of Cr (≤ 2400 ppb) was only found in severe HS conditions. Moreover, supplemental Cr caused a significant linear reduction in the blood triglycerides and glucose concentrations (P < 0.05). The blood concentrations of triiodothyronine, thyroxine, and insulin increased linearly, and the corticosterone concentration reduced, with increasing supplemental Cr (P < 0.05). There was a non-linear inverse association between Cr supplementation and cortisol level (Pnon-linearity < 0.05), and the lowest concentration of cortisol was observed with the supplementation of 1000 ppb of Cr. Meanwhile, significant positive linear associations between Cr supplementation and bursa percentage, thymus percentage, infectious bronchitis vaccine titer, avian influenza vaccine titer, Newcastle disease vaccine titer, cutaneous basophil hypersensitivity response, and serum immunoglobulin G level were found (P < 0.05). However, Cr supplementation caused a linear reduction in the heterophil/lymphocyte ratio (P < 0.05). Based on the obtained results, the recommended optimum amount of supplemental Cr is 1100 ppb.

The relationship between mitochondrial ND5 gene polymorphisms and in vitro embryo production in Sanjabi sheep.

The aim of this study was to investigate mitochondrial ND5 gene polymorphisms and their relationship with in vitro maturation (IVM) and in vitro culture (IVC) of Sanjabi sheep. Blood and ovarian samples of adult ewes were obtained from a local slaughterhouse. For each ovarian sample, cumulus-oocyte complexes larger than 3 mm in diameter were aspirated from follicles, and their IVM and IVC rates were recorded. A 666-bp fragment of the ND5 gene was amplified using the polymerase chain reaction. The samples were genotyped using a modified single-stranded conformation polymorphism (SSCP) method, and an association study was conducted with IVM and IVC rates. Six different SSCP patterns, designated A, B, C, D, E and F with respective frequencies of 8, 47, 4, 4, 32 and 5%, respectively, were observed. According to the results of association analysis, there was no significant association between the ND1 gene polymorphisms and the IVM and IVC rates (P > 0.05).

Effects of different concentrations of Chir98014 as an activator of Wnt/beta-catenin signaling pathway on oocyte in-vitro maturation and subsequent embryonic development in Sanjabi ewes.

The present study was conducted to investigate the effects of the activator factor of the WNT pathway, chir98014, leading to the in vitro sheep oocyte maturation medium, on the cumulus cell development, different nuclear maturation stages and the following process of embryonic development. Experiments included (a) addition of different concentrations (0, 0.1, 0.5, 1 µm) of chir98014 to the maturation medium and evaluation of the cumulus cell expansion, (b) addition of different concentrations of chir98014 to the maturation medium and investigation of different nuclear maturation stages, (c) addition of different concentrations of chir98014 to the maturation medium and examination of the subsequent embryonic maturation process and (d) addition of different concentrations of chir98014 to the embryonic development culture medium (the first 48 hr) and investigation of the subsequent embryonic development process. The extracted data were analysed using the SPSS software, considering the significance level of p < .05 and making the mean comparisons. The results showed that the addition of the 0.1 µM concentration of chir98014 to the maturation medium had no significant effects on the oocyte maturation and embryo development post-fertilization but it enhanced the Cumulus-oocyte complexes (COCs) expansion. In the fourth experiment, the low concentration of chir98014 in the embryo culture media improved the embryo development process, whereas the high one had a detrimental effect on it, as compared to the control group. Thus, the presence of the lower concentrations of this compound in the embryonic culture medium had favourable effects on the development of embryos.

Effect of Chromium Supplementation on Performance, Carcass Characteristics, Blood Biochemistry, and Immune Response of Unstressed Broiler Chickens: a Dose-Response Meta-Analysis.

Studies investigating the effects of Chromium (Cr) supplementation on unstressed broiler chickens have reported an inconsistent association between Cr supplementation and broiler chickens' responses. We conducted a dose-response meta-analysis of previous studies to assess the dose-response associations between Cr supplementation and performance parameters, carcass traits, blood metabolites, and immune indices of non-stressed broiler chickens. The results showed that Cr supplementation was not associated with feed intake, body mass gain, and feed conversion ratio. There was a J-shaped relationship between Cr supplementation and carcass relative weight, and Cr supplementation at about 1145 µg/kg diet produced the highest response. However, supplemental Cr had no effects on the other carcass traits, including breast, leg, abdominal fat, and liver relative weights. There was a strong evidence of nonlinear associations between Cr supplementation and the blood concentration of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol (P < 0.05). The maximum reduction in blood LDL concentration was observed when Cr was supplemented at about 540 µg/kg diet, and Cr at the dose of 588 µg/kg of diet caused the greatest enhancement in the blood HDL concentration. However, supplementation with Cr did not change the blood total cholesterol and triglycerides concentrations. Additionally, a strong inverse association was found between Cr supplementation and blood glucose concentration. Furthermore, positive linear associations between Cr supplementation and the relative weight of bursa and thymus and the antibody titer to Newcastle disease vaccine were detected. However, supplemental Cr had no effect on the spleen relative weight and titer against avian influenza vaccine. Findings from this meta-analysis demonstrate that Cr supplementation is positively associated with carcass relative weight, blood HDL concentration, and immune response and inversely associated with blood glucose and LDL concentrations in non-stressed broiler chickens.

Retraction : Resveratrol treatment during in vitro maturation enhances cumulus expansion and developmental competence of Sanjabi sheep oocytes.

This article released online on January 18, 2019 as advance publication was withdrawn from consideration for publication in The Journal of Reproduction and Development at author's request.

Retraction: Resveratrol treatment during in vitro maturation enhances cumulus expansion and developmental competence of Sanjabi sheep oocytes.

This article released online on January 18, 2019 as advance publication was withdrawn from consideration for publication in The Journal of Reproduction and Development at author's request.