Improving effects of dietary rumen protected γ‐aminobutyric acid additive on apparent nutrient digestibility,growth performance and health status in heat‐stressed beef cattle

This study was aimed to investigate the effects of rumen‐protected γ‐aminobutyric acid (RP‐GABA) on apparent nutrient digestibility, growth performance and health status in heat stressed beef cattle. Fifty Jinjiang Yellow cattle were randomly assigned to 5 treatments (10 animals/treatment). Treatments 1 to 5 were basal diets affixed with 0 (control), 8, 16, 24 and 32 mg of RP‐GABA/kg of body weight (BW) respectively. The trial lasted 45 days. Apparent digestibility of crude protein (CP), crude fiber (CF) and calcium (Ca) quadratically increased with increasing RP‐GABA (p < .01), while apparent digestibility of phosphorus (P) tended to quadratically increase (p = .09). Dietary supplementation with increasing RP‐GABA linearly increased DM digestibility and average daily gain (ADG) (p < .01), whereas the feed to gain (F:G) ratio linearly decreased with increasing RP‐GABA (p < .01). The average daily feed intake (ADFI) value tended to linearly increase with RP‐GABA supplementation (p = .08). Total protein (TP), blood urea nitrogen (BUN) and malondialdehyde (MDA) levels quadratically decreased (p < .01) with increasing RP‐GABA, however albumin (ALB), glucose (GLU), superoxide dismutase (SOD), triiodothyronine (T3) and thyroxine (T4) levels quadratically increased (p ≤ .01). In conclusion, the present results indicated that dietary supplementation with RP‐GABA led to improved nutrient digestibility, growth performance and antioxidant status in heat stressed beef cattle.     

The protective effect of γ‐aminobutyric acid on the development of immune function in chickens under heat stress

This study aimed to investigate the protective effect of γ‐aminobutyric acid (GABA) on the development of immune function in chicks under heat stress (HS). One‐day‐old male Wenchang chicks were randomly divided into control (CK), HS and GABA+HS groups. The GABA+HS group was fed with 0.2 ml GABA solution (50 mg/kg) daily by oral gavage. The HS and GABA+HS groups were placed in 40 ± 0.5 °C environment for 2 h heat treatment from 13:00 each day. Blood samples were routinely taken at 14, 21, 28, 35 and 42 days respectively, and the contents of T and B lymphocyte subsets in the blood and tissue were analysed by flow cytometry after FITC/PE double staining; the plasma levels of interleukin (IL)‐2, immunoglobulin (Ig)A, IgG and IgM were determined using ELISA. The thymus and the bursa of fabricius were also collected to analyse for organ index and observe for the changes in tissue microstructure. In addition, the chicks received primary and secondary immunizations with attenuated Newcastle disease (ND) vaccine (LaSota strain) at 7 and 28 days respectively; conventional hemagglutination inhibition (HI) assay was performed to monitor the titre changes in plasma antibody against ND virus in the birds. Our results indicated that the indices of both thymus and bursa of fabricius, the intactness of tissue structure and development, the plasma levels of IL‐2, IgA, IgG and IgM, the titres of ND antibody, and the levels of B and T lymphocyte subsets in HS group were all significantly lower than those in CK group (p < 0.05). However, all above indices were significantly improved in GABA+HS group compared with those in HS group (p < 0.05). These results demonstrated that while HS seriously affected the development of immune function in Wenchang chicks, GABA effectively alleviated the damages of HS to the development of immune function in chicks.     

Effect of γ‐aminobutyric acid on growth performance and immune function in chicks under beak trimming stress

This experiment was undertaken to examine the effect of beak trimming stress on the growth performance and immune system, and to consider possible roles of γ‐aminobutyric acid (GABA) in this stress response. Results showed that body weight, feed intake and relative spleen weight were significantly increased by GABA at 80 mg/kg (P < 0.05) under beak trimming stress, whereas the relative organ weights of the bursa of fabricius and thymus were not significantly affected (P > 0.05). Adrenocorticotropic hormone concentration in serum was highest for chicks fed the GABA‐deficient water and was significantly decreased by the supplement of GABA at days 1, 3 and 5 after beak trimming (P < 0.05). The supplement of GABA significantly increased the proportions of CD4⁺ and CD8⁺ lymphocytes, especially at the dose of 60 mg/kg (P < 0.05). The levels of interleukin (IL)‐1β, lipopolysaccharide‐induced tumor necrosis factor‐α and IL‐6 in serum were significantly decreased by GABA at 80 mg/kg (P < 0.05). All the three cytokines expressed in the spleen were significantly decreased by GABA at 80 mg/kg when birds were under beak trimming stress (P < 0.05). It is concluded that beak trimming suppressed the immune response of chicks, whereas the immune response of chicks could be improved by GABA supplementation.     

Effects of dietary fibre level and body weight of pigs on nutrient digestibility and available energy in high‐fibre diet based on wheat bran or sunflower meal

The objectives of this study were (a) to investigate the effect of body weight (BW) on available energy in fibre‐rich diets containing two NDF levels; and (b) to evaluate the effect of fibre type and NDF level on AA digestibility. In Exp. 1, barrows (24 at 33.4 ± 1.1 kg; 24 at 86.8 ± 3.3 kg) were randomly allotted to 4 diets containing a high protein basal (HPB), a low protein basal (LPB), 70% HPB + 30% wheat bran (WB) (HPB‐WB) and 70% LPB + 30% sunflower meal (SFM) (LPB‐SFM). In Exp. 2, barrows (24 at 33.5 ± 1.8 kg; 24 at 87.0 ± 3.8 kg) were randomly allotted to 4 diets containing no SFM with 12% NDF (SFM0LF), no SFM with 16% NDF (SFM0HF), 24% SFM with 12% NDF (SFM24LF) and 24% SFM with 16% NDF (SFM24HF). In Exp. 3, twelve barrows (35.5 ± 3.4 kg) fitted with T‐cannulas were allotted to two 6 × 4 Youden square design with 6 diets (4 same diets as in Exp. 2 and 2 nitrogen‐free diets). The concentration of DE, ME and ATTD of GE, CP, NDF and ADF in diets was greater (p < .01) when fed to 90 kg pigs compared with 30 kg pigs. The ME in ingredients was not affected by BW. The ATTD of NDF was negatively correlated with the CF (r = ?.98; p < .01), ADF (r = ?.99; p < .01) and ADL content (r = ?.96; p < .01). The ME of diets was negatively correlated with the ATTD of CF (r = ?.98; p < .01). The addition of SFM increased the standardized ileal digestibility (SID) of Met (p < .05). In conclusion, diets rich in fibre had different nutritional values at different pig weight stages. The AA digestibility depends mainly on chemical composition of diets.     

Dietary supplementation with glutamine and γ‐aminobutyric acid improves growth performance and serum parameters in 22‐ to 35‐day‐old broilers exposed to hot environment

This study was designed using 360 21‐day‐old chicks to determine the influences of diet supplementation with glutamine (5 g/kg), γ‐aminobutyric acid (GABA, 100 mg/kg) or their combinations on performance and serum parameters exposed to cycling high temperatures. From 22 to 35 days, the experimental groups (2 × 2) were subjected to circular heat stress by exposing them to 30–34 °C cycling, while the positive control group was exposed to 23 °C constant. The blood of broilers was collected to detect serum parameters on days 28 and 35. Compared with the positive control group, the cycling high temperature decreased (p < 0.05) the feed consumption, weight gain and serum total protein (TP), glucose, thyroxine (T4), insulin, alkaline phosphatase (ALP), glutamine, GABA and glutamate levels, while increased (p < 0.05) the serum triglyceride (TG), corticosterone (CS), glucagon (GN), creatine kinase (CK), glutamic oxaloacetic transaminase (GOT), nitric oxide synthase (NOS), glutamate pyruvate transaminase (GPT) and lactate dehydrogenase (LDH) levels during 22–35 days. However, dietary glutamine (5 g/kg) increased (p < 0.05) the feed consumption, weight gain and serum levels of glutamine, TP, insulin and ALP, but decreased (p < 0.05) the serum TG, CK, GOT, NOS and GPT levels. Diet supplemented with GABA also increased (p < 0.05) weight gain and the serum levels of TP, T4, ALP, GABA and glutamine. In addition, the significant interactions (p < 0.05) between glutamine and GABA were found in the feed consumption, weight gain and the serum ALP, CK, LDH, GABA, T3 and T4 levels of heat‐stressed chickens. This research indicated that dietary glutamine and GABA improved the antistress ability in performance and serum parameters of broilers under hot environment.     

Calming effect of orally administered γ‐aminobutyric acid in Shih Tzu dogs

The calming effects of γ‐aminobutyric acid (GABA) by oral administration were investigated in four adult Shih Tzu dogs. Three dosage levels (1, 2 and 4 mg/kg body weight) and non‐administration were tested by an increase and decrease method. Changes in activity (for 1.5 h) and urinary cortisol levels (pre‐administration, 3 and 7 h later) of dogs were monitored after administration. Without reference to dosage level, the mean times spent standing (P = 0.06), sitting (P < 0.05) and walking (P < 0.05) tended to decrease compared to non‐administration. A significant depression in the urinary cortisol level was observed at 7 h after administration (P < 0.05). These results indicate that orally administrated GABA exerts calming effects on dogs as well as humans.     

Influence of Bacillus subtilis GCB‐13‐001 on growth performance,nutrient digestibility,blood characteristics,faecal microbiota and faecal score in weanling pigs

The present study investigated the influence of Bacillus subtilis GCB‐13‐001 on growth performance, nutrient digestibility, blood characteristics, faecal microbiota and faecal score in weanling pigs. A total of 120 weaning pigs [(Landrace × Yorkshire) × Duroc; 7.73 ± 0.75 kg (28 days of age)] were randomly allotted into three treatments according to their initial body weight (BW) and gender in a 6‐week experiment. There were 8 replication pens in each treatment, with five pigs/pen. Dietary treatment groups were as follows: (a) basal diet (CON), (b) CON + 0.1% Bacillus subtilis GCB‐13‐001 1 × 10⁸ CFU/kg (T1) and (c) CON + 0.1% Bacillus subtilis GCB‐13‐001 1 × 10⁹ CFU/kg (T2). Days 1 to 7, the BW and ADG with T2 treatment were higher (p < .05) than CON treatment, as well as F:G showed trends in linear reduction (p < .1). Days 8 to 21, the BW and ADG were improved (p < .05) in pigs offered T1 and T2 diets compared with CON diet. Days 22 to 42, BW and ADG were higher (p < .05) in pigs fed T2 diet than CON and T1 diets, and the pigs fed T1 diet had higher BW than CON treatment. Overall, the ADG with the T2 treatment was higher (p < .05) than that with the T1 and CON treatments, and pigs offered T1 treatment had higher (p < .05) ADG than CON treatment. Moreover, F:G ratio were significantly decreased (p < .05) by T2 treatment compared with CON treatment. The faecal Lactobacillus counts were improved, and E. coli counts were reduced (p < .05) in pigs fed T2 diet compared with CON at the end of the experiment. In conclusion, supplementation of 0.1% Bacillus subtilis GCB‐13‐001 1 × 10⁹ CFU/kg has shown a beneficial effect in improving BW, increase ADG, decrease F:G ratio.     

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.     

Crystalline amino acids supplementation improves the performance and carcass traits in late‐finishing gilts fed low‐protein diets

This study investigated the effects of amino acids (AA) supplementation in low‐crude protein (CP) diets on the growth performance and carcass characteristics in late‐finishing gilts. Ninety gilts (93.8 ± 5.5 kg) were randomly allotted to one of the five diets which consisted of a normal‐CP (137 g/kg) or four low‐CP (105 g/kg) diets for 28 days. The low‐CP diets were supplemented with lysine + threonine + methionine (LCM), LCM + tryptophan (LCT), LCT + valine (LCV) or LCV + isoleucine (LCI), respectively. Non‐significant difference in average daily gain (ADG) was obtained in gilts receiving the control and LCV diet, which was higher than that of gilts fed the LCM diet (p < .05). The additions of crystalline AA in the low‐CP diet resulted in the improvements in ADG (linear and quadratic effect, p < .05) and fat‐free lean gain (quadratic effect, p < .05) and influenced the valine concentration (linear and quadratic effect, p < .05) and proportion of saturated fatty acid (linear effect, p < .05) in longissimus muscle. The results indicated that the valine supplementation could further improve the performance in 94 to 118 kg gilts fed the 105 g/kg CP diet.     

Biological and biochemical characteristics of male reproductive system,serum metabolites and carcass quality of Japanese quails by the supplementation of Pinus ponderosa leaves and α‐tocopherol acetate

The aim of the current study was to evaluate the effect of dietary supplementation of Pinus ponderosa leaves ( pine leaves) and α‐tocopherol acetate (vitamin E) powder on male reproductive system, serum metabolites and carcass characteristics of Japanese quails. A total of 360‐day‐old male quails were purchased from the open market and kept at poultry shed for ninety‐four days. After ten days of adaptation, all quails were randomly assigned into 4 groups, control (IC); supplemented with α‐tocopherol acetate (IE) at the rate of 150 mg/L; Pinus ponderosa leaves (IP) at the rate of 150 mg/L; and 70 mg α‐tocopherol acetate and 70 mg Pinus ponderosa leaves (IEP). Pinus ponderosa leaves and α‐tocopherol acetate supplementation had not significantly (p > .05) effected on final body weight gain, feed intake and feed conversion ratio of quails. The high‐density lipoprotein cholesterol (HDLC) and total cholesterol (TC) were significantly (p > .05) affected by IE and IP groups as compared to IC and IEP groups. Triglyceride (TG), glutathione peroxidase (GPx) and superoxide dismutase (SOD) significantly (p < .05) increased in all treatment groups except for the IC group. Aspartate transaminase (AST) significantly (p > .05) decreased in treatment groups as compared to control group. Overall, the mineral levels significantly (p < .05) increased in treatment groups as compared to control. Cloacal gland index values, the quantity of foam production and testis weight were significantly (p < .05) increased in treatment groups. It was concluded that the supplementation of Pinus ponderosa leaves and α‐tocopherol acetate improved the testis weight, foam production, serum antioxidant enzymes and mineral level especially zinc in Japanese quail considered an indicative characteristic of higher sperm production rate and improved sexual activity. Further, higher gametogenesis rate, sperm production or reproductive behaviour including different hormonal level will be analysed in future study.     

Effect of protease derived from Pseudoalteromonas arctica supplementation on growth performance,nutrient digestibility,meat quality,noxious gas emission and blood profiles in finishing pigs

This study was conducted to evaluate the effects of dietary supplementation of protease derived from Pseudoalteromonas arctica (PPA) in finishing pigs. A total of 160 pigs were used in this 10‐week trial. Dietary treatment groups were as follows: CON (basal diet); TRT1 (basal diet + 0.1% PPA); TRT2 (basal diet + 0.2% PPA); and TRT3 (basal diet + 0.3% PPA). During weeks 1–5, pigs fed with different levels of PPA‐supplemented diet showed linear increase (p < .05) in the apparent total tract digestibility (ATTD) of nitrogen (N) and linear decrease (p < .05) in the concentrations of serum total protein. During weeks 6–10, pigs fed with different levels of PPA‐supplemented diet showed a linear decrease in feed conversion ratio (p < .05). During the overall period, there was a linear decrease in feed conversion ratio (p < .05) associated with the inclusion of PPA. Pigs fed diets with 0.2% PPA supplementation had lower (p < .05) feed conversion ratio than those fed CON diet during weeks 6–10 and the overall period, and had higher (p < .05) ATTD of N than those fed CON diet during weeks 1–5. Pigs fed diets with PPA supplementation had lower (p < .05) concentrations of serum total protein than those fed CON diet on week 5. In conclusion, dietary supplementation with PPA diet has beneficial effects on growth performance, nutrient digestibility, backfat thickness and the concentrations of serum total protein.     

Effects of inoculants on the fermentation characteristics and in vitro digestibility of reed canary grass (Phalaris arundinacea L.) silage on the Qinghai‐Tibetan Plateau

To effectively use local available grass resources to cover the winter feed shortage on the Qinghai‐Tibetan Plateau, direct‐cut and wilted reed canary grass (RCG) silages were prepared by using a rolled‐bale system, and their ensiling characteristics and in vitro digestibility were studied. Silages were treated without (control) or with inoculants including LP (Lactobacillus plantarum), LPLB (L. plantarum, L. buchneri), and LPLBc (L. plantarum, L. buchneri, and cellulase), and were stored at ambient temperature (5.7–14.6°C) for 90 days. Compared with control, the inoculated silages increased (p < .05) lactic acid and acetic acid contents, and reduced (p < .05) final pH value and ammonia‐N ratio of total N. The highest WSC content (41.2 g/kg DM) occurred for LPLB‐inoculated silage, whereas LPLBc‐treated silage displayed the lowest contents of NDF (522.9 g/kg DM) and ADF (275.5 g/kg DM). In addition, LPLBc‐inoculated silage had the highest in vitro gas production (51.0 ml/g DM), in vitro DM digestibility (619.3 g/kg DM), and metabolic energy (9.6 kJ/kg DM). These results confirmed that treatments with inoculants at ensiling could improve silage fermentation and in vitro digestibility of RCG, and this could be a potential winter feed for animals on the Qinghai‐Tibetan Plateau.     

Ruminal epithelial insulin‐like growth factor‐binding proteins 2, 3, and 6 are associated with epithelial cell proliferation

The aim of this study was to identify factors that regulate ruminal epithelial insulin‐like growth factor‐binding protein (IGFBP) expression and determine its role in rumen epithelial cell proliferation. Primary bovine rumen epithelial cells (BREC) were incubated with short‐chain fatty acids (SCFAs) at pH 7.4 or 5.6, lactate, lipopolysaccharide (LPS), insulin‐like growth factor‐I (IGF‐I), ‐II (IGF‐II), or recombinant bovine IGFBP2 (rbIGFBP2). The mRNA expression levels of IGFBP in BREC were analyzed using quantitative real‐time polymerase chain reaction (qRT‐PCR). The proliferation rate of BREC was analyzed using a WST‐1 assay. IGFBP2 gene expression tended to be lower with SCFA treatment (p < .1), and IGFBP6 gene expression was significantly lower with SCFA treatment (p < .05). IGFBP3 and IGFBP6 gene expression tended to be higher with d ‐Lactate treatment (p < .1). IGFBP3 gene expression was significantly higher (p < .05) with LPS treatment. BREC treated with IGF‐I grew more rapidly than vehicle control‐treated cells (p < .01); however, recombinant bovine rbIGFBP2 inhibited IGF‐I‐induced proliferation. IGF‐II and/or rbIGFBP2 did not affect BREC proliferation. Taken together, SCFA treatment decreased IGFBP2 and IGFBP6 expression in rumen epithelial cells, and lower expression of these IGFBP might promote rumen epithelial cell proliferation by facilitating IGF‐I.     

β‐hydroxy‐β‐methyl butyrate promotes leucine metabolism and improves muscle fibre composition in growing pigs

The aim of this study was to investigate the effects of excess leucine (Leu) vs. its metabolites α‐ketoisocaproate (KIC) and β‐hydroxy‐β‐methyl butyrate (HMB) on Leu metabolism, muscle fibre composition and muscle growth in growing pigs. Thirty‐two pigs with a similar initial weight (9.55 ± 0.19 kg) were fed 1 of 4 diets for 45 days: basal diet, basal diet + 1.25% L‐Leu, basal diet + 1.25% KIC‐Ca, basal diet + 0.62% HMB‐Ca. Results indicated that relative to the basal diet and HMB groups, Leu and KIC groups exhibited increased Leu concentrations and decreased concentrations of isoleucine, valine and EAAs in selected muscle (p < 0.05) and had lower mRNA levels of MyHC I and higher expression of MyHC IIx/IIb (p < 0.05), and there was no significant difference between the basal and HMB‐supplemented groups. Moreover, the mRNA expression levels of AMPKα and UCP3 were higher but the myostatin mRNA levels were lower in the soleus muscle of the HMB group than those from other groups (p < 0.05). These findings demonstrated that doubling dietary Leu content exerted growth‐depressing effects in growing pigs; dietary KIC supplementation induced muscular branched‐chain amino acid imbalance and promoted muscle toward a more glycolytic phenotype; while dietary HMB supplementation promoted the generation of more oxidative muscle types and increased muscle growth specially in oxidative skeletal muscle, and these effects of HMB might be associated with the AMPKα‐Sirt1‐PGC‐1α axis and mitochondrial biogenesis.     

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.     

Glycerine as a feed supplement for beef and dairy cattle: A meta-analysis on performance,rumen fermentation,blood metabolites and product characteristics

This study aimed to comprehensively evaluate the effects of glycerine supplementation at various concentrations on performance, rumen fermentation, blood metabolites and product characteristics of beef and dairy cattle in vivo by using a quantitative meta-analysis approach. Meta-analysis was performed by integrating a total of 52 studies from 39 articles and 182 treatments into a database. Data were constructed into an intact database and did not distinguish between beef and dairy cattle, except for the parameters of production performance and product characteristics. Data summarized were analysed by using a statistical meta-analysis that employed a fixed effect of glycerine supplementation level and a random effect of various studies for both beef and dairy cattle. Significance of an effect was stated at the probability level of p < .05, and p < .1 was considered as a tendency of significant. Results revealed that there was a linear decrease on dry matter intake (p < .01) and daily gain (p < .05) of beef cattle with the increasing levels of glycerine supplementation. Glycerine supplementation did not decrease milk production of lactating dairy cows. Molar proportion of acetate in the rumen was decreased (p < .001), whereas propionate and butyrate proportions were increased (both at p < .001) by glycerine supplementation. Generally, glycerine did not change nutrient digestibility except that it reduced fibre digestibility (p < .001). Glycerine supplementation linearly lowered triglyceride and NEFA concentrations (both at p < .05) in the blood serum, but not other blood metabolites. Glycerine tended to linearly increase (p < .1) carcass percentage in beef cattle. Increasing dietary glycerine levels decreased milk fat (p < .01) but elevated milk protein (p < .001). Glycerine tended to increase milk lactose (p < .1) by following a quadratic pattern. The proportion of MUFA was increased quadratically by glycerine supplementation (p < .05), whereas glycerine tended to decrease SFA by following a quadratic pattern (p < .1).     

Dominant follicles development and estradiol‐17β concentrations in non‐ovulating and ovulating post‐partum Bulgarian Murrah buffaloes

This study was designed to evaluate the dominant follicles development and the estradiol‐17β concentrations in non‐ovulating and ovulating post‐partum buffaloes. Sixteen Bulgarian Murrah buffaloes were submitted to transrectal ultrasonographic examination from the 1st post‐partum day until day 50, 3 days apart. The follicular diameter of the different categories of follicles and the ovulations was recorded. The animals were allocated into two groups: I (n = 6) non‐ovulating and II (n = 10) ovulating buffaloes. Serum estradiol‐17β concentrations on the days for dominant follicle registration were measured by enzyme‐linked immunosorbent assay. The results were statistically processed by analysis of variance, non‐parametric and correlation analysis. The mean intervals between calving and first dominant follicle detection differed significantly (p < .05) among the groups (19.5 ± 6.2 vs. 13.8 ± 5.1 days), while the mean intervals between registered dominant follicles from two successive waves were comparable. The mean follicular diameters for the same category follicles in both groups were similar. Different estradiol‐17β concentrations (p < .05) for the first dominant follicle between non‐ovulating (23.5 ± 7.0 pg/ml) and ovulating (33.3 ± 8.4 pg/ml) buffaloes were determined. The cumulative percentages of buffaloes with firstly detected dominant follicle and ovulating animals correlated positively (r ≥ .84; p < .05) to post‐partum days. In conclusion, non‐ovulating and ovulating post‐partum Bulgarian Murrah buffaloes showed differences in the development of the first dominant follicle and estradiol‐17β concentrations during the time of dominant follicles detection.     

Nitric oxide impacts bovine sperm capacitation in a cGMP‐dependent and cGMP‐independent manner

We aimed to elucidate whether NO acts in in vitro sperm capacitation in bovine via cGMP/PKG1 pathway. For this, cryopreserved bovine sperm were capacitated in vitro with 20 µg/ml heparin (Control) plus treatments: 1 mM L‐arginine (L‐arg, NO precursor), 50 µM Rp‐8‐Bromo‐β‐phenyl‐1,N²‐ethenoguanosine‐3′,5′‐cyclic monophosphorothioate (Rp‐8‐Br‐cGMPS, selective inhibitor of the binding site for cGMP in PKG1), 1 mM 2‐Phenyl‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl 3‐oxide (PTIO, NO scavenger), and the combinations of L‐arg + RP‐8‐Br‐cGMPS and L‐arg + PTIO. Sperm motility and vigour were determined by phase‐contrast microscopy, capacitation status by chlortetracycline staining, and the intracellular concentration of cGMP was measured by ELISA. Data were subjected to analysis of variance and means compared with SNK test at 5% probability. Motility and vigour were lower in sperm treated with PTIO when compared to Control and other treatments (p < .05). The L‐arg treatment showed the highest percentage of capacitated sperm when compared to the Control and other treatments (Rp‐8‐Br‐cGMPS, L‐arg + Rp‐8‐Br‐cGMPS and PTIO) (69.8 ± 3.4%, 51.2 ± 3.0, 51.1 ± 2.1, 51.2 ± 3.0 and 45.5 ± 2.7, respectively) (p < .05). The capacitation ratio (%) was lower in treatments with Rp‐8‐Br‐cGMPS, L‐arg + Rp‐8‐Br‐cGMPS and PTIO, respectively (p < .05). Lastly, cGMP concentration (pmol/ml) was lower in PTIO and L‐arg + PTIO (1.3 ± 0.3 and 1.6 ± 0.4) and was higher in Rp‐8‐Br‐cGMPS and L‐arg + Rp‐8‐Br‐cGMPS (3.7 ± 0.4 and 4.0 ± 0.5) treatments. We showed that during in vitro capacitation of cattle: (a) NO influences sperm motility and vigour; (b) NO is associated with cGMP synthesis through two independent pathways and (c) the cGMP/PKG1 pathway has a partial role in sperm capacitation and does not involve the L‐arg/NO.     

Effect of oak (Quercus persica) acorn level on apparent digestibility,ruminal fermentation,nitrogen balance and urinary purine derivatives in pregnant goats

The aim of this experiment was to investigate the effect of dietary oak (Quercus persica) acorn (OA) level on dry matter intake (DMI), apparent nutrient digestibility, nitrogen (N) utilization, ruminal fermentation, protozoa population and urinary purine derivatives (PD) during the last 60 days of goat pregnancy. Twenty‐four multiparous pregnant goats (41.7 ± 2.3 kg BW) were assigned to one of three experimental diets consisted of control diet (C, without OA) and diets containing 20 (OA₂₀) or 40 g/100 g of OA (OA₄₀) on a DM basis in a completely randomized block design. Goats fed OA₄₀ had lower DMI (p < .01), DM (p < .01), OM (p < .01) and NDF (p < .05) digestibility, ruminal NH₃‐N concentration (p < .01), N intake (p < .01) and N retention (p < .01). Crude protein digestibility and ruminal acetate and total volatile fatty acid (VFA) concentration were lower in animals fed OA‐contained diets (p < .01), whereas ruminal propionate concentration was higher in goats fed the C diet (p < .01). Animals fed OA₄₀ had higher faecal N excretion and lower urinary N excretion (p < .01). Urinary PD was lower in goats fed diets containing OA in relation to those fed the C diet (p < .01). Total protozoa population decreased linearly with increasing OA level in the diet (p < .05). These results suggest that feeding OA, especially high level, has negative impacts on DMI, nutrient digestibility, VFA concentration, N retention and urinary PD excretion that may have adverse effects on metabolism and performance of pregnant goats.