Effects of maternal treatment with β‐hydroxy‐β‐metylbutyrate and 2‐oxoglutaric acid on femur development in offspring of minks of the standard dark brown type

The aim of the study was to evaluate the effect of the diet, mother type and sex of the offspring on the mechanical and geometric parameters of long bones as well as bone tissue density in minks. Primiparous and multiparous dams were supplemented with β‐hydroxy β‐methylbutyrate (a metabolite of leucine, at the daily dosage of 0.02 g/kg of body weight) and/or 2‐oxoglutaric acid (a precursor of glutamine, at the daily dosage of 0.4 g/kg of body weight) during gestation. The diet did not influence bone tissue density and the length of the humerus. An increase in the length of the femur was noted in male offspring delivered by multiparous dams. The diet resulted in an increase in the weight of the humerus in males from multiparous dams and a decrease in offspring from primiparous dams. Heavier femora were noted in male offspring delivered by both types of dams. The maximum elastic strength of the humerus was higher in the offspring delivered by multiparous than primiparous dams, irrespective of the offspring sex. The diet resulted in reduction in the ultimate strength of the femur in the male offspring delivered by primiparous dams. Only females born by multiparous dams, irrespective of the diet, showed a significant increase in the cross‐sectional area of the humerus, while a significant decline was noted in males delivered by multiparous dams and in all the offspring delivered by primiparous dams. An increase in the cross‐sectional area of the femur was noted in the offspring delivered by multiparous dams, while reduction was observed in the offspring delivered by primiparous dams. These results have shown for the first time that the presence of β‐hydroxy‐β‐methylbutyrate or 2‐oxoglutaric acid in the diet of pregnant primiparous or multiparous dams unambiguously affects the geometry and mechanical properties of offspring's long bones.     

ORIGINAL ARTICLE: Fish bones – a highly available calcium source for growing pigs

In general, there is a lack of scientific documentation of nutritional value of marine by‐products. The bone fraction from fish has been regarded as waste. Due to the high mineral content of fish bones, this material can be well suitable as a natural calcium source. In the present study, apparent calcium absorption of different fish bone sources was tested using growing pigs. The experimental diets consisted of boiled salmon frames, or salmon, saithe or cod bones treated with enzymes. Calcium carbonate (CaCO₃) was used as control. The experimental diets were formulated to contain 0.7% total calcium of which the added calcium source to be tested contributed about 71% (study 1) and 86% (study 2). Except for the calcium and phosphorus sources, the animals received similar basal diets. Apparent calcium digestibility coefficient was calculated using yttrium as indicator (both studies) and was based on complete collection of faeces and urine (study 2). The experimental design was parallel and cross‐over in study 1 and study 2, respectively. In study 1, piglets getting salmon bone treated with enzymes had significantly higher calcium absorption than piglets getting boiled fish bone or calcium carbonate. Therefore, in the second study only enzymatically treated fish bones were included. The higher calcium absorption from enzymatically treated salmon bone was also found in study 2, but this time not significant. Calcium from boiled salmon bones in study I, and from enzymatically treated saithe and cod bones in study II were absorbed as well as the calcium carbonate control. The results indicate that fish bones may be a useful and well absorbed calcium source. Due to the high mineral content of the bone fraction, salmon bones can be well suitable as a natural calcium and phosphorus source in, for example, food, feed or as supplement.     

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.     

Effect of intake of linoleic acid and α‐linolenic acid levels on conversion into long‐chain polyunsaturated fatty acids in backfat and in intramuscular fat of growing pigs

A study was conducted to determine the effect of two levels of linoleic acid (LA) intake at either high or low α‐linolenic acid (ALA) intake on their conversion and subsequent deposition into long‐chain (20–22 C‐atoms) polyunsaturated fatty acids (LC PUFA) in muscle and backfat in growing pigs. In a 2 × 2 factorial arrangement, 32 gilts from 8 litters were assigned to one of four dietary treatments, varying in LA and ALA intakes. Low ALA and LA intakes were 0.15 and 1.31 g/(kg BW^0.75/day), respectively, and high ALA and LA intakes were 1.48 and 2.65 g/(kg BW^0.75/day) respectively. There was a close positive relation between intake of ALA and the concentration of ALA in backfat and in intramuscular fat. Dietary ALA did not affect the concentration of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), but increased docosapentaenoic acid (DPA) in backfat. High ALA intake did not significantly affect DHA but significantly increased EPA, 20:3 n‐3 and DPA concentrations in intramuscular fat. The n‐3 LC PUFA proportion in backfat was increased from approximately 1–3%, which may be useful to enrich meat with these fatty acids. The effect of ALA intake on n‐3 LC PUFA was suppressed by LA intake. Dietary ALA suppressed the concentration of n‐6 LC PUFA in blood plasma by more than 50%. When compared at equal incremental dose, the inhibiting effect of ALA on blood arachidonic acid was stronger than the stimulating effect of LA as precursor.     

ORIGINAL ARTICLE: Putative reference genes for gene expression studies in propionate and β‐hydroxybutyrate treated bovine adipose tissue explants

Accurate gene expression normalization using a stable reference gene (RG) improves the reliability of quantitative real‐time PCR (qPCR) results. Therefore, a validation of RGs should be done before their use. Only few studies on RGs have been done in cattle, and none in bovine adipose tissue (AT) explants, therefore, we characterize the effects of an in vitro treatment with propionate and β‐hydroxybutyric acid (BHB) on the mRNA content of these RGs comparing the output data from the geNorm^TM and the Normfinder^© program. geNorm^TM and Normfinder^© estimated the most stable RGs in the following sequence for subcutaneous and for retroperitoneal AT explants treated with propionate: low density lipoprotein receptor‐related protein 10 (LRP10) > hippocalcin‐like 1 (HPCAL1) > glyceraldehyde‐phosphate‐dehydrogenase (GAPDH) > ribosomal protein S9 (RPS9) > RNA polymerase II (Pol II) > beta2 actin (ACTB) > 18S ribosomal RNA (18S rRNA). BHB treated AT explants yielded a different stability ranking for RGs using geNorm^TM: HPCAL1, GAPDH > Pol II > LRP10 > ACTB > RPS9 > 18S rRNA. Normfinder^© estimated a different stability ranking for the RGs as shown in the following sequence for subcutaneous and retroperitoneal AT explants treated with BHB: HPCAL1 > Pol II > GAPDH > ACTB > LRP10 > RPS9 > 18S rRNA. Subsequent pairwise analysis of variation of RGs using geNorm^TM suggested that LRP10, HPCAL1 and GAPDH should be used for accurate normalization of subcutaneous and retroperitoneal AT explants treated with propionate, while HPCAL1, GAPDH and Pol II should be used for BHB treatment.     

Branched‐chain amino acid ratios in low‐protein diets regulate the free amino acid profile and the expression of hepatic fatty acid metabolism‐related genes in growing pigs

Liver metabolism is affected by nutrients. The aim of this study was to explore the effects of low‐protein diets (17% crude protein, CP) supplemented with branched‐chain amino acids (BCAAs), including leucine (Leu), isoleucine (Ile) and valine (Val), on hepatic amino acid profile and lipid metabolism in growing pigs. The ratio of Leu : Ile : Val in all groups was 1 : 0.51 : 0.63 (20% crude protein, CP), 1 : 1 : 1 (17% CP), 1 : 0.75 : 0.75 (17% CP), 1 : 0.51 : 0.63 (17% CP) and 1 : 0.25 : 0.25 (17% CP) respectively. Results revealed that compared to the positive control group (1 : 0.51 : 0.63, 20% CP), the low‐protein diets significantly augmented the concentrations of most essential amino acids and non‐essential amino acids (p < .05), with the greatest values observed in the 1 : 0.25 : 0.25 group. Moreover, relative to the control, the low‐protein diets with the Leu : Ile : Val ratio ranging from 1 : 0.75 : 0.75 to 1 : 0.25 : 0.25 markedly downregulated the mRNA abundance of acetyl‐CoA carboxylase (ACC), lipoprotein lipase (LPL) and fatty acid‐binding protein 4 (FABP‐4) (p < .05), and upregulated the mRNA expression of hormone‐sensitive lipase (HSL), peroxisome proliferator‐activated receptor‐g coactivator‐1α (PGC‐1α), uncoupling protein 3 (UCP3) and liver carnitine palmitoyltransferase 1 (L‐CPT‐1) (p < .05). Therefore, our data suggest that protein‐restricted diets supplemented with optimal BCAA ratio, that is, 1 : 0.75 : 0.75–1 : 0.25 : 0.25, induce a shift from fatty acid synthesis to fatty acid oxidation in the liver of growing pigs. These effects may be associated with increased mitochondrial biogenesis.     

Sudden death in the presence of overt β‐adrenergic receptor activation in guinea pigs immediately following isoflurane anesthesia

Observations A case series of sudden death is reported in five consecutive guinea pigs following anesthesia with inhalational isoflurane during β‐adrenergic receptor stimulation with isoproterenol. Sustained‐release isoproterenol pellets or mini‐osmotic pumps were implanted subcutaneously in male Dunkin–Hartley guinea pigs as part of a research study to assess the interplay of adrenergic receptor activation and the development of atrial arrhythmias. The continuous exposure to isoproterenol resulted in a similar presentation and eventual sudden death in all guinea pigs exposed to inhalational isoflurane between 15 to 40 minutes after discontinuation of anesthesia. Death occurred in guinea pigs in this case series despite the fact that doses of isoproterenol used were more than 10‐fold lower than previously reported in guinea pigs in the absence of isoflurane anesthesia. The cause of death was suspected to be due to an interaction of isoproterenol with isoflurane anesthesia, as placebo implantation or anesthesia alone did not result in cardiac arrest. Of four subsequent guinea pigs anesthetized with the combination of xylazine and ketamine (X/K), three survived isoproterenol implantation for the full 21‐day study period while one died perioperatively. Conclusions There was an increased rate of post‐anesthetic mortality associated with isoproterenol pellet implantation in guinea pigs anesthetized with isoflurane compared to X/K. This may be due to the detrimental effects of the combination of isoflurane during overt β‐adrenergic receptor activation or cardioprotective effects of X/K anesthesia during β‐adrenergic receptor hyperactivity.     

ORIGINAL ARTICLE: Intravenous injections of cobalt reduce fatty acid desaturation products in milk and blood of lactating cows

The objective of this study was to determine whether intravenous infusion of Co affects levels of fatty acid desaturation products in bovine milk. Six cows were assigned to two replicated 3 × 3 Latin squares with 14‐day periods. Treatment occurred on days 1 to 5 and depuration occurred on days 6–14. Two treatments were tested, the first consisting of per os supplementation of 3.5 g Co daily in the form of Co acetate and the second consisting of intravenous injection of 175 mg Co daily in the form of Co acetate diluted in saline solution. The third treatment was a control. Both Co treatments decreased cis‐9 18:1 levels from approximately 18 to 14 g/100 g fatty acids, and increased 18:0 levels from 11 to 17 g/100 g fatty acids in milk fat (p < 0.001). The proportions of cis‐9 10:1, cis‐9 12:1, cis‐9 14:1, cis‐9 16:1 and cis‐9 17:1 decreased (p < 0.001), whereas 17:0 and trans‐11 18:1 increased (p < 0.001). In blood plasma, levels of cis (6,9,12) 18:3 (p < 0.001) and cis (8,11,14,17) 20:4 (p = 0.008) decreased after both the Co treatments. It is concluded that intravenous supply of Co reduces levels of fatty acid desaturation products in both bovine milk and blood.     

Increased fatty acid β‐oxidation as a possible mechanism for fat‐reducing effect of betaine in broilers

Two hundred and forty 1‐day‐old male Arbor Acres broiler chickens were randomly assigned to five dietary treatments with six replicates of eight chickens per replicate cage for a 42‐day feeding trial. Broiler chickens were fed a basal diet supplemented with 0 (control), 250, 500, 750 or 1000 mg/kg betaine, respectively. Growth performance was not affected by betaine. Incremental levels of betaine decreased the absolute and relative weight of abdominal fat (linear P < 0.05, quadratic P < 0.01), low‐density lipoprotein cholesterol (LDL‐C), triglyceride (TG) and total cholesterol (TC) (linear P < 0.05), and increased concentration of nonesterified fatty acid (NEFA) (linear P = 0.038, quadratic P = 0.003) in serum of broilers. Moreover, incremental levels of betaine increased linearly (P < 0.05) the proliferator‐activated receptor alpha (PPARα), the carnitine palmitoyl transferase‐I (CPT‐I) and 3‐hydroxyacyl‐coenzyme A dehydrogenase (HADH) messenger RNA (mRNA) expression, but decreased linearly (P < 0.05) the fatty acid synthase (FAS) and 3‐hydroxyl‐3‐methylglutaryl‐CoA (HMGR) mRNA expression in liver of broilers. In conclusion, this study indicated that betaine supplementation did not affect growth performance of broilers, but was effective in reducing abdominal fat deposition in a dose‐dependent manner, which was probably caused by combinations of a decrease in fatty acid synthesis and an increase in β‐oxidation.     

Potential role of ALDH3A2 on the lipid and glucose metabolism regulated by (‐)‐hydroxycitric acid in chicken embryos

This study aimed to investigate the effect of (‐)‐hydroxycitric acid ((‐)‐HCA) on lipid and glucose metabolism, and further analyzed these actions whether associated with modulation of aldehyde dehydrogenase 3 family member A2 (ALDH3A2) expression in chicken embryos. Results showed that (‐)‐HCA decreased triglyceride content and lipid droplet counts, while these effects induced by (‐)‐HCA were reversed in chicken embryos pre‐transfected with sh4‐ALDH3A2. (‐)‐HCA decreased malic enzyme, acetyl‐CoA carboxylase, fatty acid synthase, and sterol regulatory element binding protein‐1c mRNA level, while increased carnitine palmitoyl transferase 1A (CPT1A) and peroxisome proliferators‐activated receptor α (PPARα) mRNA level; and the action of (‐)‐HCA on lipid metabolism factors had completely eliminated in embryos pre‐transfected with sh4‐ALDH3A2. Chicken embryos pre‐transfected with sh4‐ALDH3A2 had eliminated the increasing of serum glucose and hepatic glycogen content induced by (‐)‐HCA. (‐)‐HCA decreased phosphofructokinase‐1 and increased G6P, fructose‐1,6‐bisphosphatase, phosphoenolpyruvate carboxykinase (PEPCK), and pyruvate carboxylase mRNA level in chicken embryos. Similarly, the effect of (‐)‐HCA on these key enzyme mRNA level was reversed in embryos pre‐transfected with sh4‐ALDH3A2. Furthermore, (‐)‐HCA increased PPAR‐γ‐coactivator‐1α (PGC‐1α), PPARα, hepatic nuclear factor‐4A, PEPCK, and CPT1A protein level, and these actions of (‐)‐HCA disappeared in embryos pre‐transfected with sh4‐ALDH3A2. These results indicated that (‐)‐HCA reduced fat accumulation and accelerated gluconeogenesis via activation of PGC‐1α signaling pathway, and these effects of (‐)‐HCA might associate with the increasing of ALDH3A2 expression level in chicken embryos.     

ORIGINAL ARTICLE: Effect of rendering on protein and fat quality of animal by‐products

This work studies the effect of rendering on quality of meat and bone meals (MBM) processed in two Spanish rendering plants according to the standard procedure recommended by 96/499/EC Directive for MBM category III. Twelve samples of raw animal by‐products and their corresponding meals were analysed for chemical composition, amino acids (AA) content, FDNB‐reactive lysine content, pepsin digestibility, protein dispersibility index (PDI) and fatty acids (FA) content. There was a high variation in MBM composition between and within plants, mainly in the ash and fat content. Rendering caused a decrease in the total (p < 0.05) and the essential (p < 0.01) AA content (in crude protein basis) in both plants, because of a decrease in lysine (p < 0.001), methionine (p < 0.05), threonine (p < 0.01), leucine (p < 0.01), valine (p < 0.01) and phenylalanine (p < 0.01). Besides, there was a reduction in the cystine (p < 0.001), serine (p < 0.01) and aspartic acid (p < 0.01) content. The FDNB‐reactive lysine to total lysine ratio and pepsin digestibility only decreased (p < 0.001) in the plant with more severe treatment conditions, whereas the PDI increased (p < 0.05) by the process in both plants. The saturated to unsaturated FA ratio increase on average from 0.73 to 0.88 after rendering, because of the decrease in both linoleic and linolenic acids content and the increase in palmitic and stearic acids content. The results indicate that rendering has negative effects on protein and fat quality of MBM. Variability between and within plants is attributed to differences in raw material, processing conditions and fat removing efficiency. Therefore, a continuous monitoring is recommended to assure the quality of each batch before use.     

Dietary supplementation of β‐hydroxy‐β‐methylbutyrate in animals – a review

The leucine metabolite β‐hydroxy‐β‐methylbutyrate (HMB) has been studied by many researchers over the last two decades. In particular, the utility of HMB supplementation in animals has been shown in numerous studies, which have demonstrated enhanced body weight gain and carcass yield in slaughter animals; positive immunostimulatory effect; decreased mortality; attenuation of sarcopenia in elderly animals; and potential use in pathological conditions such as glucocorticoid‐induced muscle loss. The aim of this study was to summarize the body of research on HMB supplementation in animals and to examine possible mechanisms of HMB action. Furthermore, while the safety of HMB supplementation in animals is well documented, studies demonstrating efficacy are less clear. The possible reasons for differences in these findings will also be examined.     

Effects of addition of Aspergillus oryzae culture and 2‐hydroxyl‐4‐(methylthio) butanoic acid on milk performance and rumen fermentation of dairy cows

To investigate effects of Aspergillus oryzae culture (AOC) and 2‐hydroxy‐4‐(methylthio) butanoic acid (HMB) on milk performance and rumen fermentation of dairy cows. Sixty‐four multiparous Chinese Holstein cows were randomly allocated into four experimental diets: (i) Control diet; (ii) AOC diet: 5 g AOC/day per head; (iii) HMB diet: 25 g HMB/day; and (iv) AH diet: 5 g AOC plus 25 g HMB/day. Added HMB tended to increase the yield of milk protein (P = 0.06) and 3.5% fat‐corrected milk (P = 0.08) and milk fat content (P = 0.09). Milk fat yield (P = 0.03) and the contents of milk protein (P = 0.05) were increased by adding HMB. The cows fed on AOC diet had a tendency for higher body weight (BW) gain (P = 0.08). Addition of AOC, HMB and AH increased content of microbial protein (MCP) and total volatile fatty acids (VFA) (P < 0.01) in rumen fluid. Populations of rumen fungi, Fibrobacter succinogenes and Ruminococcus flavefaciens relative to total bacterial 16S rDNA (P ≤ 0.03) and activity of carboxymethylcellulase (CMCase) (P < 0.01) were increased with added AOC or HMB. It is inferred that added AOC or HMB can increase the contents of MCP and total VFA potentially by stimulating rumen microbe populations and CMCase activity.     

ORIGINAL ARTICLE: The approach to the mechanism of calcitonin gene‐related peptide‐inducing inhibition of food intake

The aim of this study was to investigate the anorectic mechanism of calcitonin gene‐related peptide (CGRP) in rats. Intraperitoneal injection of CGRP (50 μg/kg) resulted in decline (p < 0.05) in the food intake of rats at 0.5, 1, 2 and 4 h in comparison with saline control. Compared with saline‐treated group, the levels of hypothalamic 3′,5′‐cyclic adenosine monophosphate (cAMP) and plasma glucagon were increased (p < 0.05) in CGRP‐treated group, but insulin level was decreased (p < 0.05). No significant changes (p > 0.05) in the plasma leptin were observed between two treatment groups. Calcitonin gene‐related peptide injection down regulated (p < 0.05) both neuropeptide Y (NPY) and melanin‐concentrating hormone (MCH) genes at mRNA levels, but up regulated (p < 0.05) the expression of cholecystokinin (CCK) gene. The correlations analysis showed that food intake was negatively correlated (p < 0.05) with CCK mRNA, cAMP and glucagon levels. Moreover, there existed negative correlations (p < 0.05) between MCH mRNA and glucagon levels, and positive correlations (p < 0.05) between insulin and leptin levels. The results showed that cAMP acting as the second messenger may play a vital role in the anorectic effects of CGRP. Calcitonin gene‐related peptide could stimulate anorexigenic neuropeptides (i.e. CCK) and/or inhibit orexigenic neuropeptides (i.e. NPY and MCH) expression, and ultimately suppressed food intake that was functionally coupled to cAMP/PKA pathway activation.     

Optimal dietary lysine to threonine ratio in pigs (30–110 kg BW) derived from observed dietary amino acid efficiency

Optimal ratio of lysine (Lys) to threonine (Thr) in diets for growing barrows [genotype: Piétrain × (Large White × German Landrace)] was established at 30, 50, 70, 90 and 110 kg body weight (BW). N balance studies were conducted with diets based on constant mixture of wheat, barley, soybean meal and field peas. Supplementation of crystalline amino acids (AA) provided diets with Lys (diet A) and Thr (diet B) in first limiting position. For each BW range, totally 28 individual N balance data were utilized for assessing model parameters (exponential N utilization model) of dietary efficiency of Lys and Thr, respectively. Observed maximal dietary efficiency of Lys and Thr provided the database for conclusion of optimal dietary Lys to Thr ratio. Based on applied experimental conditions, BW dependent Lys to Thr ratio could not be concluded. On average, the dietary ratio Lys to Thr = 1:0.61 ± 0.02 was obtained as optimal for growing pigs.     

ORIGINAL ARTICLE: Application of soybean meal,soy protein concentrate and isolate differing in α‐galactosides content to low‐ and high‐fibre diets in growing turkeys

The aim of this experiment was to investigate the physiological and growth response of young turkeys (up to 8 weeks of age) to dietary replacement of soybean meal (SBM) by soy protein concentrate (PC) or protein isolate (PI). This replacement resulted in a differentiated dietary concentration of α‐galactosides of over 2.5% in the SBM diet, approximately 2% with a mixture SBM and PC, 1% with a PC diet and 0.1% with a PI diet. Each treatment was applied in two ways: with lower (3.5%) or higher (5.3%) dietary crude fibre content, made by supplementation with soybean hulls. The highest and lowest body weight of turkeys was recorded both after the first and second 4‐week half of the study in the PC and PI‐type diets respectively. A gradual withdrawal of α‐galactosides from a diet was accompanied by a decline in ileal tissue mass, ileal viscosity and activity of endogenous maltase (the latter was found to be significant at 4 weeks of age). At the same time, two‐way anova revealed that an elevated level of crude fibre (HF treatment) caused an increase in ileal tissue mass (p < 0.05 after 4 weeks of feeding) as well as a decrease in activity level of intestinal sucrase and maltase. The presence of raffinose family oligosaccharides in a diet, in contrast to dietary crude fibre level, significantly affected the caecal metabolism. The rate of bacterial production of short‐chain fatty acids in the caeca was distinctly diminished by dietary withdrawal of α‐galactosides. In conclusion, the soy protein concentrate, in contrast to the protein isolate preparation, exerted positive effects on the turkeys’ growth and gastrointestinal tract physiology and should be considered as an effective SBM substitute.