Growth of rumen papillae in weaned calves is associated with lower expression of insulin‐like growth factor‐binding proteins 2, 3, and 6

This study aimed to characterize the relationship between the growth of rumen papillae in calves and the mRNA expression of insulin‐like growth factor‐binding proteins (IGFBPs) in the rumen papillae. The length of rumen papillae, the mRNA expression of IGFBPs in rumen papillae by quantitative real‐time PCR, and the presence of insulin‐like growth factors I and II (IGF‐I and II) by immunohistochemistry (IHC) were analyzed in nine Holstein calves divided into three groups: suckling (2 weeks, n = 3), milk‐continued (8 weeks, n = 3), and weaned (8 weeks, n = 3). The length of rumen papillae was greater (p < 0.01) in weaned calves than in suckling and milk‐continued calves, whereas the expressions of IGFBP2, IGFBP3, and IGFBP6 genes were lower (p < 0.05) in the rumen papillae of weaned calves than in milk‐continued calves. Thus, rumen papillae length and IGFBP2, 3, and 6 expressions were negatively correlated. The IHC analysis showed that IGF‐I and IGF‐II were present in the rumen epithelium of calves. These results suggested that the growth of rumen papillae after weaning is associated with the induction of IGFs by the low levels of IGFBP2, IGFBP3, and IGFBP6.     

The preliminary study on the effects of growth hormone and insulin‐like growth factor‐I on κ‐casein synthesis in bovine mammary epithelial cells in vitro

The effects of growth hormone (GH) and insulin‐like growth factor‐I (IGF‐I) on protein synthesis and gene expression of κ‐casein in bovine mammary epithelial cell in vitro were studied. The treatments were designed as follows: the growth medium without serum was set as the control group, while the treatments were medium supplemented with GH (100 ng/ml), IGF‐I (100 ng/ml), and GH (100 ng/ml) + IGF‐I (100 ng/ml). The quantity of κ‐casein protein was measured by ELISA, and the κ‐casein gene (CSN3) expression was examined by real‐time quantitative PCR (RT‐qPCR). Compared with the control group, all the experimental groups had greater (p < 0.05) expression of CSN3. The concentration of κ‐casein followed a similar response as CSN3, but the difference between the treatments and the control was not statistically significant (p > 0.05). Furthermore, no synergistic effect of GH and IGF‐I was observed for both the κ‐casein concentration and CSN3 expression. It is therefore concluded that GH or IGF‐I can independently promote the expression of CSN3 in bovine mammary epithelial cells in vitro.     

Aspartame supplementation in starter accelerates small intestinal epithelial cell cycle and stimulates secretion of glucagon‐like peptide‐2 in pre‐weaned lambs

The objective of this study was to test the hypothesis that aspartame supplementation in starter diet accelerates small intestinal cell cycle by stimulating secretion and expression of glucagon‐like peptide ?2 (GLP‐2) in pre‐weaned lambs using animal and cell culture experiments. In vivo, twelve 14‐day‐old lambs were selected and allocated randomly to two groups; one was treated with plain starter diet (Con, n = 6) and the other was treated with starter supplemented with 200 mg of aspartame/kg starter (APM, n = 6). Results showed that the lambs received APM treatment for 35 d had higher (p < .05) GLP‐2 concentration in the plasma and greater jejunum weight/live body weight (BW) and jejunal crypt depth. Furthermore, APM treatment significantly upregulated (p < .05) the mRNA expression of cyclin D1 in duodenum; and cyclin A2, cyclin D1, cyclin‐dependent kinases 6 (CDK6) in jejunum; and cyclin A2, cyclin D1, CDK4 in ileum. Moreover, APM treatment increased (p < .05) the mRNA expression of glucagon (GCG), insulin‐like growth factor 1 (IGF‐1) in the jejunum and ileum and mRNA expression of GLP‐2 receptor (GLP‐2R) in the jejunum. In vitro, when jejunal cells were treated with GLP‐2 for 2 hr, the 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide (MTT) OD, IGF‐1 concentration, and the mRNA expression of IGF‐1, cyclin D1 and CDK6 were increased (p < .05). Furthermore, IGF‐1 receptor (IGF‐1R) inhibitor decreased (p < .05) the mRNA expression of IGF‐1, cyclin A2, cyclin D1 and CDK6 in GLP‐2 treatment jejunal cells. These results suggest that aspartame supplementation in starter accelerates small intestinal cell cycle that may, in part, be related to stimulate secretion and expression of GLP‐2 in pre‐weaning lambs. Furthermore, GLP‐2 can indirectly promote the proliferation of jejunal cells mainly through the IGF‐1 pathway. These findings provide new insights into nutritional interventions that promote the development of small intestines in young ruminants.     

Effect of genistein on IGF‐1 and IGFBP‐1 in young and aged female rat ovary

The objective of this study was to assess the effects of genistein (GEN) on expression of insulin‐like growth factor 1 (IGF‐1) and insulin‐like growth factor binding protein 1 (IGFBP‐1) in young and aged rat ovary. Forty young female Sprague Dawley (SD) rats (200 ± 20 g) and forty aged female SD rats (490 ± 20 g) were selected and according to weight, they were divided into the following five groups with eight animals in each: negative control group (NC), low‐dose group (L), middle‐dose group (M), high‐dose group (H) and positive control group (PC). GEN group received GEN of 15, 30, 60 mg/kg respectively. It lasted 30 days. Concentrations of serum hormones, IGF‐1 and IGFBP‐1 were determined by enzyme‐linked immunosorbent assay (ELISA). Gene and protein expressions of IGF‐1 and IGFBP‐1 were determined by real‐time PCR and Western blot respectively. Compared with NC, GEN significantly increased oestradiol‐17β(E₂) level in aged rat, reduced luteinizing hormone (LH) level in young and aged rat. Serum levels of IGFBP‐1 in young rats were significantly higher in GEN groups (p < 0.05). mRNA and protein expression levels of IGF‐1 and IGFBP‐1 were positively correlated with GEN dose. GEN could significantly reduce the ratio of IGF‐1/IGFBP‐1 of aged rats. Multivariate Cox regression analysis result showed IGF‐1 and IGFBP‐1 levels significantly correlated with GEN dose. We speculate that there is an association between the addition of GEN and expression of IGF‐1 and IGFBP‐1, and the relationship between them is different in young and aged rat.     

Short-chain fatty acids inhibit bovine rumen epithelial cells proliferation via upregulation of cyclin-dependent kinase inhibitors 1A,but not mediated by G protein-coupled receptor 41

Short-chain fatty acids (SCFAs) play a critical role in regulation of rumen epithelial growth. The mechanisms underlying the regulatory effects of SCFAs on the proliferation of bovine rumen epithelial cells (BRECs) remain unknown; however, SCFAs can bind to G protein-coupled receptor 41 (GPR41); hence, the regulatory effects of SCFAs on BRECs proliferation may be mediated by GPR41. Here, we investigated the molecular mechanisms underlying the effects of SCFAs and GPR41 on BRECs proliferation. We demonstrated that SCFAs activate the expression of GPR41 and inhibit (p < .05) BRECs proliferation, while the GPR41 knockdown (GPR41KD) BRECs exhibited (p < .05) slow proliferation compared with controls. The treatment of BRECs with 10 mM SCFAs significantly enhanced (p < .05) expression of cyclin-dependent kinase inhibitors 1A (CDKN1A), 2A (CDKN2A) and 2B (CDKN2B) and inhibited (p < .05) their transition from G1 to S phase of the cell cycle, compared with controls. Remarkably, the GPR41KD BRECs treated with SCFAs restored high level of CDKN1A, relative to GPR41KD BRECs, but did not affect (p > .05) the expression of CDKN2A and CDKN2B. The GPR41KD BRECs had significantly reduced (p < .05) cyclin-dependent kinase 4 (CDK4) and cyclin D2 mRNA abundance compared with controls. The GPR41KD BRECs treated with SCFAs significantly decreased (p < .05) CDK4, cyclin D2, CDKN2A and CDKN2B mRNA abundance compared with BRECs treated with SCFAs. Overall, our results demonstrated that downregulation of CDK4 and cyclin D2 likely mediates the inhibitory effects of GPR41KD on BRECs proliferation. Additionally, CDKN1A plays a vital role in mediating the inhibitory effect of SCFAs on the BRECs proliferation, and that these changes are not mediated by GPR41.     

Elevated cyclin D1 expression is governed by plasma IGF‐1 through Ras/Raf/MEK/ERK pathway in rumen epithelium of goats supplying a high metabolizable energy diet

The objective of this study was to explore the underlying mechanism of insulin‐like growth factor 1 (IGF‐1)–caused cell proliferation of rumen epithelium in goats fed a high metabolizable energy (ME) diet. In this study, young goats were fed either a low ME [LL, n = 9, ME: 0.57 MJ/kg^0.75/day] or high ME [HL, n = 9, ME: 1.00 MJ/(kg^0.75/day)] diet for 42 day. The time duration of G₁‐phase was shortened as a result of enhanced expression of cyclin D1 mRNA in the HL group (p < 0.05). It was suggested that a high ME diet promoted cell transition from G₀/G₁ to S‐phase via cyclin D1. The level of phosphorylation of ERK was higher in HL than LL group (p < 0.05). In cell culture, the ERK was phosphorylated by IGF‐1 treatment. The proliferative effects of insulin‐like growth factor 1 (IGF‐1, 25 ng/ml) on [³H] thymidine (TdR) incorporation into DNA and on cyclin D1 protein expression of rumen epithelial cells were inhibited by PPP (the inhibitor of type 1 IGF receptor) (p < 0.05) and ERK inhibitor (p < 0.05) in vitro. Thus, IGF‐1 up‐regulated cyclin D1 expression and accelerated G₁‐phase progression in the cell cycle through Ras/Raf/MEK/ERK pathway in rumen epithelium of goats.     

Deoxynivalenol induces oxidative stress,inflammatory response and apoptosis in bovine mammary epithelial cells

Deoxynivalenol (DON) is a toxic secondary metabolite produced by Fusarium graminearum. It is one of the most common feed contaminants that poses a serious threat to the health and performance of dairy cows. This study investigated the in vitro cytotoxicity of DON on bovine mammary epithelial cells (MAC‐T). DON at different concentrations (0.25, 0.3, 0.5, 0.8, 1 or 2 μg/ml) inhibited the growth of MAC‐T cells after 24 hr of exposure (p < .001). DON at 0.25 μg/ml increased lactate dehydrogenase (LDH) leakage (p < .05); decreased glutathione (GSH) levels (p < .001), total superoxide dismutase (T‐SOD) activity and total antioxidant capacity (T‐AOC; p < .01); and increased malondialdehyde (MDA) concentration (p < .01) in MAC‐T cells after 24 hr of exposure. We also observed that DON increased reactive oxygen species (ROS) levels in cells incubated for 9, 15 and 24 hr (p < .001). DON at 0.25 μg/ml triggered oxidative damage in MAC‐T cells. Furthermore, it induced an inflammatory response in the cells incubated for 9, 15 and 24 hr (p < .05) by increasing the mRNA expression levels of nuclear factor kappa B, myeloid differentiation factor 88 (MyD88), tumour necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), IL‐6, cyclooxygenase‐2 and IL‐8. We further examined the effect of DON on apoptosis. DON prevented normal proliferation of MAC‐T cells by blocked cell cycle progression in 24 hr (p < .001). In addition, the apoptosis rate measured using annexin V‐FITC significantly increased (p < .05) with increase in the mRNA expression level of Bax (p < .01) and increase in the Bax/Bcl‐2 ratio (p < .01) in cells incubated for 24 hr. In summary, DON exerts toxic effects in MAC‐T cells by causing oxidative stress, inducing an inflammatory response, affecting cell cycle and leading to apoptosis.     

Effect of L‐theanine on meat quality,muscle amino acid profiles,and antioxidant status of broilers

This study investigated the effect of L ‐theanine on carcass traits, meat quality, muscle antioxidant capacity, and amino acid (AA) profiles of broilers. Three hundred 1‐day‐old Ross 308 male broilers were randomly allotted to five groups with six replicates. Birds were fed the basal diet or basal diet with 300, 600, 900, or 1,500 mg/kg L ‐theanine for 42 consecutive days. The results showed that L ‐theanine quadratically increased dressing percentage, eviscerated percentage, and leg muscle yield (p < .05). Meanwhile, drip loss, cooking loss, shear force, L*_24h, and muscle lactate content decreased quadratically in response to dietary L ‐theanine supplementation (p < .05), while pH_24h and muscle glycogen content were quadratically improved by L ‐theanine (p < .05). Notably, the contents of muscle malondialdehyde and protein carbonyl, and the activities of muscle total antioxidant capacity, catalase, and glutathione peroxidase decreased quadratically in response to dietary L ‐theanine supplementation (p < .05), suggesting that the oxidative stress level of muscle was decreased quadratically. Moreover, L ‐theanine quadratically increased the concentrations of most of muscle essential AA, nonessential AA, and flavor AA (p < .05). In conclusion, L ‐theanine can be used as a valuable feed additive to modulate carcass traits, meat quality, muscle antioxidant status, and AA profiles of boilers, and its optimum addition level is 600 mg/kg based on the present study.     

Effects of chestnut tannins on intestinal morphology,barrier function,pro‐inflammatory cytokine expression,microflora and antioxidant capacity in heat‐stressed broilers

A study was conducted to evaluate the effects of chestnut tannins (CT) on intestinal morphology, barrier function, pro‐inflammatory cytokine expression, microflora and antioxidant capacity in heat‐stressed broilers. Four hundred 28‐day‐old male Ross 308 broilers were randomly assigned into four groups, with 10 replicates per group and 10 broilers per replicate. The broilers in the normal (NOR) group were kept at 22 ± 1°C and fed the basal diet, and each of the other three groups were treated with cyclic heat (33 ± 1°C from 0800 to 1800 and 22 ± 1°C from 1800 to 0800) and fed the basal diet with 0 (HT), 1 (CT1) or 2 (CT2) g of CT/kg of diet. The experiment lasted for 14 days. Compared with the HT group, broilers in the NOR and CT2 groups had higher (p < .05) average daily gain and villus height in the jejunum and lower serum d ‐lactate (p < .001) and diamine oxidase (p < .01) levels. The addition of 2 g CT/kg of diet increased the total antioxidant capacity (p < .001) and superoxide dismutase activities (p < .05) and zonula occludens‐1 mRNA expression level (p < .05) and decreased the malondialdehyde concentration (p < .01) and mRNA expression levels of interleukin‐6 (p < .001) and nuclear factor kappa B (p < .001) in the jejunal mucosa of heat‐stressed broilers. The populations of Escherichia coli and Clostridium in the jejunum (p < .01) and caecum (p < .05) of broilers in the HT group were higher than those in the NOR and CT2 groups. In conclusion, the addition of 2 g CT/kg of diet seemed to be a feasible means of alleviating the negative effects of heat stress on the growth performance and intestinal function of broilers.     

N‐Acetyl‐d‐galactosamine prevents soya bean agglutinin‐induced intestinal barrier dysfunction in intestinal porcine epithelial cells

Soya bean agglutinin (SBA) is a glycoprotein and the main anti‐nutritional component in most soya bean feedstuffs. It is mainly a non‐fibre carbohydrate‐based protein and represents about 10% of soya bean‐based anti‐nutritional effects. In this study, we sought to determine the effects of N‐Acetyl‐D‐galactosamine (GalNAc or D‐GalNAc) on the damage induced by SBA on the membrane permeability and tight junction proteins of piglet intestinal epithelium (IPEC‐J2) cells. The IPEC‐J2 cells were pre‐cultured with 0, 0.125 × 10^?4, 0.25 × 10^?4, 0.5 × 10^?4, 1.0 × 10^?4 and 2.0 × 10^?4 mmol/L GalNAc at different time period (1, 2, 4 and 8 hr) before being exposed to 0.5 mg/ml SBA for 24 hr. The results indicate that pre‐incubation with GalNAc mitigates the mechanical barrier injury as reflected by a significant increase in trans‐epithelial electric resistance (TEER) value and a decrease in alkaline phosphatase (ALP) activity in cell culture medium pre‐treated with GalNAc before incubation with SBA as both indicate a reduction in cellular membrane permeability. In addition, mRNA levels of the tight junction proteins occludin and claudin‐3 were lower in the SBA‐treated groups without pre‐treatment with GalNAc. The mRNA expression of occludin was reduced by 17.3% and claudin‐3 by 42% (p < 0.01). Moreover, the corresponding protein expression levels were lowered by 17.8% and 43.5% (p < 0.05) respectively. However, in the GalNAc pre‐treated groups, occludin and claudin‐3 mRNAs were reduced by 1.6% (p > 0.05) and 2.7% (p < 0.01), respectively, while the corresponding proteins were reduced by 4.3% and 7.2% (p < 0.05). In conclusion, GalNAc may prevent the effect of SBA on membrane permeability and tight junction proteins on IPEC‐J2s.     

Methyl donors dietary supplementation to gestating sows diet improves the growth rate of offspring and is associating with changes in expression and DNA methylation of insulin‐like growth factor‐1 gene

The study aimed to investigate the effects of maternal dietary methyl donors on the performance of sows and their offspring, and the associated hepatic insulin‐like growth factor‐1 (IGF‐1) expression of the offspring. A total of 24 multiparous sows were randomly fed the control (CON) or the CON diet supplemented with methyl donors (MD) at 3 g/kg betaine, 15 mg/kg folic acid, 400 mg/kg choline and 150 μg/kg VB₁₂, from mating until delivery. After farrowing, sows were fed a common lactation diet through a 28‐days lactation period and six litters per treatment were selected to be fed until at approximately 110 kg BW. Maternal MD supplementation resulted in greater birthweight (p < 0.05) and increased the piglet weights (p < 0.01) and litter weights (p < 0.05) at the age of day 28, compared with that in CON group. The offspring pigs in the MD group had greater ADG (p < 0.05) and tended to lower F:G ratio (p = 0.07) compared with that of CON group from day 28 to 180 of age. The offspring pigs from MD group had greater serum IGF‐1 concentrations and expressions of hepatic IGF‐1 gene and muscular IGF‐1 receptor (IGF‐1r) protein at birth (p < 0.05), and greater hepatic IGF‐1 protein (p = 0.03) and muscular IGF‐1r gene expressions (p < 0.05) at slaughter, than that from the CON group. Moreover, the methylation at the promoter of IGF‐1 gene in the liver of newborn piglets and finishing pigs was greater in the MD group than that of the CON group (p < 0.05). In conclusion, maternal MD supplementation throughout gestation could enhance the birthweight and postnatal growth rate of offspring, associated with an increased expression of the IGF‐1 gene and IGF‐1r, as well as the altered DNA methylation of IGF‐1 gene promotor.     

Effects of Saccharomyces cerevisiae supplementation on growth performance,plasma metabolites and hormones,and rumen fermentation in Holstein calves during pre‐ and post‐weaning periods

This study aimed to evaluate the effects of supplementing Saccharomyces cerevisiae (SC) during the pre‐ and post‐weaning periods on growth, metabolic and hormonal responses, and rumen fermentation in calves. Three‐week‐old Holstein calves were assigned to either control (n = 12) or SC group (n = 12), the latter of which received 2 × 10⁹ cfu/day of SC. The experiment was conducted over a period of 7 weeks around weaning. Daily gain (DG) in the SC group was higher (p < .05) than that in the control group. In the SC group, plasma glucose, insulin, and growth hormone (GH) concentrations were higher (p < .05) and concentrations of glucagon and insulin‐like growth factor 1 (IGF‐1) tended to be higher (p < .1) than in the control group. Proportion of rumen propionate and concentration of rumen ammonia nitrogen at 10 weeks of age were greater (p < .05) in the SC group than that in the control group. Supplementation of SC around weaning may improve dietary nutrient and energy availability and increase plasma GH and IGF‐1 concentrations. These changes observed in SC‐supplemented calves could be closely related to the improvement of DG.     

Changes of leukocyte counts and expression of pro‐ and anti‐inflammatory cytokines in peripheral leukocytes in periparturient dairy cows with retained fetal membranes

In dairy cows, retained fetal membranes (RFM) affect reproductive performance. The aim of this study was to examine the leukocyte counts and the gene expression of tumour necrosis factor α (TNFα), interleukin 1β (IL‐1β), IL‐8, and IL‐10 in polymorphonuclear leukocytes (PMNs) and peripheral blood mononuclear cells (PBMCs) in cows with (n = 5) or without (n = 5) RFM during the peripartum period. The lymphocyte counts in RFM cows were higher than those in control cows throughout the experiment (p < .05). The expression of IL‐8 in PMNs of control cows was higher (p < .05) compared with that of RFM cows postpartum. In cows with RFM, IL‐1β expression was higher (p < .05) in PMNs at 6 weeks postpartum whereas the expression of IL‐1β was lower (p < .05) in PBMCs at 4 weeks postpartum. The expression of IL‐10 in PBMCs of control cows was higher (p < .05) than that of RFM cows at 2 weeks prepartum and 4 weeks postpartum. Taken together, our data indicate that changes of gene expression of pro‐ and anti‐inflammatory cytokines in RFM cows might be associated with the delayed placental separation and development of uterine inflammation in RFM cows.     

m‐carboxycinnamic acid bishydroxamide improves developmental competence,reduces apoptosis and alters epigenetic status and gene expression pattern in cloned buffalo (Bubalus bubalis) embryos

Incomplete or aberrant reprogramming of nuclear genome is one of the major problems in somatic cell nuclear transfer. In this study, we studied the effect of histone deacetylase inhibitor m‐carboxycinnamic acid bishydroxamide (CBHA) on in vitro development of buffalo embryos produced by Hand‐made cloning. Cloned embryos were treated with CBHA (0, 5, 10, 20 or 50 μM) for 10 hr from the start of reconstruction till activation. At 10 μM, but not at other concentrations examined, CBHA increased (p < .05) the blastocyst rate (63.77 ± 3.97% vs 48.63 ± 3.55%) and reduced (p < .05) the apoptotic index of the cloned blastocysts (8.91 ± 1.94 vs 4.36 ± 1.08) compared to untreated controls, to levels similar to those in IVF blastocysts (4.78 ± 0.74). CBHA treatment, at all the concentrations examined, increased (p < .05) the global level of H3K9ac in cloned blastocysts than in untreated controls to that observed in IVF blastocysts. Treatment with CBHA (10 μM) decreased (p < .05) the global level of H3K27me3 in cloned blastocysts than in untreated controls but it was still higher (p < .05) than in IVF blastocysts. CBHA (10 μM) treatment increased (p < .05) the relative expression level of pluripotency‐related genes OCT‐4 and NANOG, and anti‐apoptotic gene BCL‐XL, and decreased (p < .05) that of pro‐apoptotic gene BAX than in untreated controls but did not affect the relative expression level of apoptosis‐related genes p53 and CASPASE3 and epigenetics‐related genes DNMT1, DNMT3a and HDAC1. These results suggest that treatment of cloned embryos with 10 μM CBHA improves the blastocyst rate, reduces the level of apoptosis and alters the epigenetic status and gene expression pattern.     

Polymorphism in promoter region of growth hormone receptor is associated with potential production capacity of insulin‐like growth factor‐1 in pre‐pubertal Holstein heifers

Insulin‐like growth factor‐1 (IGF‐1) is one of the important factors for growth, milk production and reproductive functions and mainly released from the liver in response to growth hormone (GH) via GH receptor (GHR) in cattle. Recently, some single nucleotide polymorphisms (SNPs) were identified in the bovine GHR gene. Some GHR‐SNPs were shown to be related to plasma IGF‐1 concentration in cattle. Hence, the capacity to IGF‐1 production in the liver might be affected by GHR‐SNP and associated with performance in the future. This study examined whether GHR‐SNP is associated with IGF‐1 production in the liver of pre‐pubertal heifers. In 71 Holstein calves, blood samples for genomic DNA extraction were obtained immediately after birth. To genotype the GHR‐SNPs in the promoter region, polymerase chain reaction (PCR) products were digested with restriction enzyme NsiI (cutting sites: AA, AG and GG). All heifers at 4 months of age were intramuscularly injected with 0.4 mg oestradiol benzoate. Blood samples were obtained from the jugular vein just before (0 h) and 24 h after injection. The number of AA, AG and GG at the NsiI site was 0, 17 and 54 respectively. In AG and GG, plasma GH concentrations were higher pre‐injection than 24 h post‐injection (p < 0.01). Moreover, plasma GH concentrations in AG post‐injection were higher than in GG (p < 0.05). In contrast, the GG genotype exhibited higher plasma IGF‐1 concentrations in pre‐injection than post‐injection (p < 0.01), although oestradiol did not change IGF‐1 concentration in the AG genotype. We conclude that the GG polymorphism in the promoter region of GHR is associated with a higher potential capacity of IGF‐1 production in the liver of cattle.     

Lactoferrin concentration and expression in New Zealand cows milked once or twice a day

This study evaluated the concentration and expression of lactoferrin (LF) in cows selected for once a day (OAD) milking compared to twice a day (TAD) milking. Milk samples were collected from the Massey University TAD and OAD herds. Milk traits and expression of LF and insulin‐like growth factor 1 (IGF‐1) were analyzed with a general linear model that included the fixed effects of milking frequency, lactation number, interaction between milking frequency and lactation number, and as covariates proportion of F, heterosis F × J and deviation from the herd median calving date. Cows milked OAD produced milk with higher (p < .01) concentrations of protein and lactose than TAD milked cows. Compared to TAD cows, cows milked OAD had higher expression of the LF gene (1.40 vs. 1.29 folds, p = .03) and the IGF‐1 gene (1.69 vs. 1.48 folds, p = .007). The correlation between the expression of LF gene and the concentration of LF in milk was strong (r = .66 p < .001), but the correlation between the expression of the IGF‐1 gene and LF concentration was stronger (r = .94, p < .001). These results suggest that milking frequency affects the milk composition and expression of milk composition genes at early lactation.     

Insulin‐like growth factor I enhances the developmental competence of yak embryos by modulating aquaporin 3

The objective of our present study was to determine the effects of insulin‐like growth factor I (IGF‐I) on the development of yak (Bos grunniens) embryos after cumulus–oocyte complex (COC) vitrification and warming followed by in vitro fertilization (IVF). In Experiment 1, the yak COCs underwent vitrification and then IVF. Embryos were incubated in synthetic oviductal fluid (SOF) supplemented with four concentrations (0, 50, 100 and 200 ng/ml) of IGF‐I, while the yak COCs without vitrification or IGF‐I supplementation acted as the control group; the BAX, BCL‐2, AQP3mRNA and aquaporin 3 (AQP3) protein expression levels in the five groups of blastocysts were evaluated using quantitative real‐time PCR and immunofluorescence analyses. In Experiment 2, the groups described above were fertilized and incubated. The cleavage rate, blastocyst rate, total cell count per blastocyst and the rate of growth of the inner cell mass (ICM) and trophectoderm (TE) were evaluated. The results were as follows: (1) the AQP3 gene expression and protein expression in the control and 100 ng/ml IGF‐I treatment groups were the highest. (2) The BAX gene expression was the lowest and the BCL‐2 gene expression was the highest in the control and 100 ng/ml IGF‐I treatment groups. (3) The rates of cleavage and blastocysts in the control and 100 ng/ml IGF‐I groups were higher than those in the other three groups. The total cell count per blastocyst in the vitrified and warmed 100 ng/ml IGF‐I group (106.7 ± 4.9) and the control group (107.3 ± 4.2) was higher than that in the vitrified and warmed 0 ng/ml IGF‐I (91.2 ± 3.1), 50 ng/ml IGF‐I (92.3 ± 3.7) and 200 ng/ml IGF‐I (92.4 ± 3.7) groups. Therefore, we conclude that IGF‐I can improve yak blastocyst developmental ability, cytomembrane permeability and formation of the blastocyst cavity after COC vitrification by improving the BAX, BCL‐2 and AQP3 expression levels.     

Comparative assessment of growth performance of three different indigenous goat breeds exposed to summer heat stress

A study was conducted to assess comparatively the growth performance of three different indigenous goat breeds during exposure to summer heat stress. The primary objective of the study was to observe the heat stress impact on the growth performance based on the body weight changes, allometric measurements, growth hormone (GH) concentration and peripheral blood mononuclear cell (PBMC) Insulin‐like growth factor‐1 (IGF‐1) mRNA expression pattern during the summer season in comparison with the local breed (Osmanabadi). Thirty‐six ten‐month‐ to one‐year‐old female goats of Osmanabadi, Malabari and Salem Black breeds were randomly divided into six groups, OC (n = 6; Osmanabadi control), OHS (n = 6; Osmanabadi heat stress), MC (n = 6; Malabari control), MHS (n = 6; Malabari heat stress), SBC (n = 6; Salem Black control) and SBHS (n = 6; Salem Black heat stress). Body weight was recorded at weekly intervals, whereas other growth and allometric measurements and blood collection were carried out at fortnightly intervals. Breed factor significantly (p < .05) influenced only few growth variables such as body weight, body mass index (BMI) and body condition score (BCS). However, heat stress treatment significantly (p < .05) reduced all growth parameters expect BMI. Further, the heat stress significantly (p < .01) increased plasma GH concentration in goats with significantly higher (p < .05) concentration recorded in OHS. Among the stress groups, the lower (p < .05) PBMC IGF‐1 mRNA expression was recorded in OHS, while the higher (p < .05) expression was observed in SBHS indicating the extreme adaptive capability of Salem Black breed. Thus, the results indicated that the Salem Black breed performed much better compared to both Osmanabadi and Malabari breeds indicating the superior ability of this breed to adapt to heat stress challenges. The results also indicated that plasma GH and IGF‐1 gene may act as ideal biomarkers for assessing the heat stress impact on growth performance in indigenous goats.     

Pre‐pubertal growth,muscle and fat accumulation in male and female sheep—Relationships with metabolic hormone concentrations,timing of puberty and reproductive outcomes

Metabolic homeostasis is aligned with changes in growth and body composition, through processes mediated by circulating metabolites and metabolic hormones, and is eventually linked to reproductive success. In the present study with sheep, we determined the relationships among phenotypic and genotypic rates of growth, muscle and fat accumulation, and the circulating concentrations of metabolic and tested for relationships with the timing of puberty and subsequent reproductive outcomes. We used 64 females and 62 males with known phenotypic values for depth of eye muscle (EMD) and fat (FAT) and known Australian Sheep Breeding Values at post‐weaning age for live weight (PWT), depth of eye muscle (PEMD) and depth of fat (PFAT). Blood plasma sampled every 20 min for 8 hr via was assayed for growth hormone (GH), insulin‐like growth factor I (IGF‐I), insulin, leptin, ghrelin, follistatin, glucose and non‐esterified fatty acids (NEFA). In males, PWT was positively related to the concentrations of GH, follistatin and glucose, whereas FAT and PFAT were positively related to IGF‐I concentrations (p < .01). Testosterone concentration was negatively related to muscle variables (p < .001) and to PFAT (p < .05). In females, the only significant relationship detected was the positive link between EMD and insulin concentrations (p < .05). Reproductive variables were only measured in females. Live weight at first oestrus was related positively to insulin concentration and negatively to GH concentration (p < .05). No other relationships with reproductive variables were significant. The relationships that were detected suggest subtle differences between the sexes in the way their metabolic homeostasis responds to changes in the rates of growth, and muscle and fat accumulation, perhaps due to interference by testosterone in the males.