Effect of dietary methionine on growth performance and insulin‐like growth factor‐I mRNA expression of growing meat rabbits

An experiment was conducted to determine the effects of different amounts of dietary methionine on growth performance, serum protein, growth hormone (GH), insulin‐like growth factor‐I (IGF‐I) concentrations and IGF‐I mRNA expression of growing meat rabbits. One hundred weaned growing meat rabbits were allocated to individual cages and randomly divided into five groups. The methionine addition concentrations of the five groups were 0, 2, 4, 6 and 8 g/kg diet (as‐fed basis) and sulphur amino acids (SAA) concentrations ranging from 3.8 to 11.6 g/kg diet, respectively. The results obtained were as follows: the average daily gain of 2, 4 and 6 g/kg diet groups was higher than that of 0 g/kg diet group (p < 0.01). The feed gain ratio of the 4 g/kg diet group was lower than those of 0 and 8 g/kg diet group (p < 0.01). Methionine concentrations did not affect serum urea nitrogen, total protein, insulin and IGF‐I concentration (p > 0.05). The quadratic effects of methionine on the serum concentration of albumin (Alb) and GH were obtained (p = 0.013, p = 0.018). The quadratic effect of methionine amount on IGF‐I mRNA expression was obtained (p = 0.045). The serum concentration of Alb of the 4 g/kg diet group was higher than those of 0 and 8 g/kg diet group (p < 0.01). The serum concentration of GH of 8 g/kg diet group was higher than that of the 0 g/kg diet group (p < 0.05). The liver IGF‐I mRNA expression of 4 g/kg diet group was higher than those of the 0 and 8 g/kg diet group (p < 0.05). Providing a diet mainly consisted of corn, wheat bran and peanut vine, the optimum dietary methionine addition concentration and SAA concentration for a weaner to 2‐month‐old growing meat rabbits were shown to be 2 and 5.7 g/kg diet respectively.     

Effects of different dietary protein levels and DL‐methionine supplementation on hair growth and pelt quality in mink (Neovision vision)

The effect of different dietary protein levels and DL‐methionine (Met) supplementation on hair growth and the resulting pelt quality in mink was studied. Four groups of male mink were fed with four isocaloric diets containing 32% (P32), 24% (P24), 16% (P16) or P24+Met (0.8%) crude protein of dry matter (DM) from September to December. Skin biopsies were taken at the pelting. Histological techniques and computer‐assisted light microscopy were used to determine the ratio of activity (ROA) of under hairs and guard hairs respectively. The results showed that when the dietary protein level reduced from 32% to 16%, body length, number and diameter of under hairs and guard hairs of minks declined, and pelt length and pelt weight of minks decreased significantly (p < 0.05). These parameters were similar between P32 and P24 with Met supplementation (p > 0.05). The hair follicle density of the winter coat was not influenced by the dietary protein levels and Met supplementation (p > 0.05). Low‐protein diets content led to a reduction of hair follicle developing to next phase. It was documented that 24% crude protein of DM with Met supplementation during growing‐furring period was sufficient for minks to express their genetic capacity to develop hair follicles and achieve the prime fur characteristics. Overall this study demonstrated that hair growth and hair properties in pelts are very dependent on the dietary protein and Met supply in the growing‐furring period of minks.     

Influences of incorporating detoxified Jatropha curcas kernel meal in common carp (Cyprinus carpio L.) diet on the expression of growth hormone‐ and insulin‐like growth factor‐1‐encoding genes

Jatropha curcas is a drought‐resistant shrub or small tree widespread all over the tropics and subtropics. The use of J. curcas (L) kernel meal in fish feed is limited owing to the presence of toxic and antinutritional constituents. In this study, it was detoxified using heat treatment and organic solvent extraction method. The detoxification process was carried out for 60 min to obtain the detoxified meal. Cyprinus carpio L. fingerlings (n = 180; avg. wt. 3.2 ± 0.07 g) were randomly distributed in five treatment groups with four replicates and fed isonitrogenous diets (crude protein 38%) for 8 weeks. The inclusion levels of the detoxified Jatropha kernel meal (DJKM) and soybean meal (SBM) were as follows: control diet was prepared with fish meal (FM) and wheat meal, without any DJKM and SBM; diets S₅₀ and J₅₀: 50% of FM protein replaced by SBM and DJKM respectively; diets S₇₅ and J₇₅: 75% of FM protein replaced by SBM and DJKM respectively. Highest body mass gain and insulin‐like growth factor‐1 (IGF‐1) gene expression in brain, liver and muscle were observed for the control group, which were statistically similar to those for J₅₀ group and significantly (p < 0.05) higher than for all other groups, whereas growth hormone gene expression in brain, liver and muscle exhibited opposite trend. Insulin‐like growth factor‐1 concentration in plasma did not differ significantly among the five groups. Conclusively, growth performance was in parallel with IGF‐1 gene expression and exhibited negative trend with GH gene expression.     

Effects of two levels of feed allocation on IGF‐I concentrations and metabolic parameters in GnRH‐immunized boars

Immunocastration of boars leads to a maintenance of growth harmone (GH) and a loss of anabolic hormones [androgens, oestrogens, insulin‐like growth factor (IGF‐I)] but an increase of voluntary feed intake. The aim of the experiment was to clarify whether IGF‐I is increased by increasing feed supply in immunocastrated boars leading to improved anabolism. Two groups of six boars were given 2 or 3 kg of feed (13.5 MJ ME/kg) daily from 18–28 weeks of age. Because in boars feed intake is limited by gonadal hormones, a group with further increased feed supply could not be included. Until week 22 (second vaccination) gonadal steroids in blood were normal but dropped rapidly thereafter. Growth harmone levels did not change following vaccination. Pigs allocated 3 kg feed had 28% higher circulating IGF‐I after the second immunization compared with pigs fed 2 kg feed daily. Higher IGF‐I was associated with increased weight gain (682.4 g/day vs. 466.7 g/day; p < 0.01) and protein synthesis (¹³C‐leucine infusion; 405 g/day vs. 247 g/day, p < 0.01). Protein breakdown (urea) was not different. Body fat (D₂O) decreased in the low feed group from 15.2% (week 19) to 6.1% (week 25). In the high feed group it remained at the level found before second vaccination (13.7% vs. 15.0%). It is concluded that in the phase of reduced testicular steroids which inhibit appetite it is possible to increase feed intake which in turn increases IGF‐I and protein deposition without accumulating excessive fat.     

Oxyntomodulin reduces expression of glucagon‐like peptide 1 receptor in the brainstem of chickens

Oxyntomodulin (OXM) is a peptide released from the gut and attenuates food intake by acting on hypothalamus. However, its role at the molecular level is not well studied. In the first section of this study, we analysed the effect of OXM on food intake behaviour after injecting into the lateral ventricle of chickens. The outcome showed that food intake decreased significantly after administering 4 nmol of OXM. In the second part, the expression of glucagon‐like peptide 1 receptor (GLP‐1R) in the brainstem was analysed by real‐time RT‐PCR. The results showed that expression of GLP‐1R was reduced to 27% and 16% at 30 and 90 mins after injection of OXM respectively. In saline‐injected chickens, no reduction in GLP‐1R was seen. It can be concluded that OXM has a down regulatory effect on the responding receptor, GLP‐1R and OXM in chicks has the same reductive effect on food intake as in the mammals.     

Alterations in the jejunum of young goats caused by feeding soy protein‐based diets

This study was designed to investigate whether soy protein or soy protein supplemented with indispensable amino acids (AA) change the protein expression pattern and utilization of pre‐cursors for RNA biosynthesis in jejunal mucosa in relation to casein and whether these changes affect mucosal cell growth. Kids were fed comparable diets based on cow`s milk, of which 50% of crude protein were replaced by either casein (CAS), soy protein (SP) or soy protein supplemented with indispensible AA (SPA) for 34 days (n = 4/group). Jejunal tissue was collected 5 h after adding a single dose of ¹⁵N‐RNA to the diet, in order to determine morphology, protein repertoire by two‐dimensional gel electrophoresis and matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry, and RNA biosynthesis by isotope ratio‐mass spectrometry. In mid‐jejunum, morphological alterations induced by partial replacement of casein with soy protein were accompanied by changes in mucosal proteins related to generation of the cytoskeleton and in pathways for mucosal RNA biosynthesis, resulting in a smaller re‐utilization of dietary RNA pre‐cursors and in an increased activity of enzymes involved in nucleic acid breakdown. Soy protein supplemented with indispensible aminoacids tended to revise mucosal growth retardation with no impact on salvage of dietary RNA pre‐cursors for mucosal RNA biosynthesis, but changes in cytoskeleton generation. Feeding soy protein with supplementation of indispensible AA does not ameliorate soy protein effects on mucosal morphology and RNA metabolism in the jejunum in a significant manner.     

Identification of apolipoprotein A‐I in the α‐globulin fraction of avian plasma

Background: Plasma protein electrophoresis is frequently used in birds as a tool for the diagnosis and monitoring of disease. Identification of proteins in individual peaks can help improve our understanding of changes in protein concentration in physiologic and pathologic conditions. Objective: The aim of this study was to verify the presence and identity the protein(s) in the prominent α‐globulin peak of orange‐winged parrots (Amazona amazonica), black kites (Milvus migrans), and rock pigeons (Columba livia). Methods: Heparinized plasma samples were obtained from 12 birds of each species. Agarose gel electrophoresis and total protein concentration were determined using standard techniques. One plasma sample from each species was then electrophoresed using high‐resolution agarose gels to isolate the α‐globulin band. Gel strips were digested in trypsin and peptides were extracted and analyzed using liquid chromatography with tandem mass spectrometry. De novo sequencing was used to identify the protein based on homology scoring against a protein database. Results: Electrophoresis verified the presence of a single prominent α‐globulin peak, usually in the α₁‐region, that had a median concentration of 9.4 g/L (range, 2.1–11.7 g/L, 21.6% of total protein) in parrots, 12.2 g/L (10.4–13.2 g/L, 35.9%) in kites, and 10.7 g/L (9.0–11.5 g/L, 40.0%) in pigeons. Mass spectrometry and sequencing analysis unequivocally identified the protein as a mature circulating form of apolipoprotein A‐I (apo A‐I) in all 3 species. Conclusions: Apo A‐I accounts for the prominent α‐globulin peak and comprises a major proportion of total protein concentration in diverse avian species. As a high‐density lipoprotein and negative acute phase protein with a pivotal role in cholesterol homeostasis, further study is warranted to determine the significance of changes in apo A‐I concentration in avian electrophoretograms.