Effects of dietary protein/energy ratio on growth performance,carcass trait,meat quality,and plasma metabolites in pigs of different genotypes

Background： The protein/energy ratio is important for the production performance and utilization of available feed resources by animals. Increased protein consumption by mammals leads to elevated feed costs and increased nitrogen release into the environment. This study aimed to evaluate the effects of dietary protein/energy ratio on the growth performance, carcass traits, meat quality, and plasma metabolites of pigs of different genotypes. Methods： Bama mini-pigs and Landrace pigs were randomly assigned to two dietary treatment groups （Chinese conventional diet with low protein/energy ratio or National Research Council diet with high protein/energy ratio; n = 24 per treatment） in a 2 x 2 factorial arrangement. Blood and muscle samples were collected at the end of the nursery, growing, and finishing phases. Results： We observed significant interactions （P 〈 0.05） between breed and diet for total fat percentage, intramuscular fat （IMF） content, protein content in biceps femoris （BF） muscle, and plasma urea nitrogen （UN） concentration in the nursery phase; for average daily gain （ADG）, average daily feed intake （ADFI）, dry matter, IMF content in psoas major （PM） muscle, and plasma total protein and albumin concentrations in the growing phase; and for drip loss and plasma UN concentration in the finishing phase. Breed influenced （P 〈 0.05） growth performance, carcass traits, and meat quality, but not plasma metabolites. Throughout the trial, Landrace pigs showed significantly higher （P 〈 0.0_5） ADG, ADFI, dressing percentage, lean mass rate, and loin-eye area than did Bama mini-pigs, but significantly lower （P 〈 0.0.5） feed/gain ratio, fat percentage, backfat thickness, and IMF content. Dietary protein/energy ratio influenced the pH value, chemical composition of BF and PM muscles, and plasma activities of glutamic-pyruvic transaminase and gamma-glutamyl transpeptidase, and plasma concentration of UN. Conclusions： Compared with Landrace pigs, Bama mini-pigs showed slower growth and lower carcass performance, but had better meat quality. Moreover, unlike Landrace pigs, the dietary protein/energy ratio did not affect the growth performance of Bama mini-pigs. These results suggest that, in swine production, low dietary protein/energy ratio may be useful for reducing feed costs and minimizing the adverse effects of ammonia release into the environment.

Effect of dietary soy oil, glucose, and glutamine on growth performance, amino acid profile, blood profile, immunity, and antioxidant capacity in weaned piglets

Weaning stress results in gastrointestinal dysfunction and depressed performance in pigs. This study aimed to investigate the effect of soy oil, glucose, and glutamine on the growth and health of weaned piglets. Compared with those in the glutamine group, piglets in the glucose and soy oil groups had greater average daily gain, average daily feed intake, and gain: feed ratio from day 0 to 14, and gain: feed ratio for the overall period. There were no differences with regard to serum amino acids among the three groups on day 14, except glycine and threonine. The serum concentration of histidine, serine, threonine, proline, and cysteine was the highest in the glutamine group, while the content of glycine and lysine in the soy oil group on day 28 was the highest among all groups. Piglets fed with glutamine had greater serum glucose and creatinine on day 14, high-density lipoprotein on day 28, and serum IgG and IgM on day 28. Piglets in the glutamine group demonstrated lower serum total superoxide dismutase on day 14 and 28; however, they demonstrated higher total superoxide dismutase and total antioxidant capacity in the duodenum and ileum on day 14. Weaned pigs supplemented with glucose or soy oil demonstrate better growth performance possibly due to their enhanced feed intake, whereas those supplemented with glutamine may have improved immunity and intestinal oxidative capacity.

Effects of dietary energy on growth performance, carcass characteristics, serum biochemical index, and meat quality of female Hu lambs

This study evaluated the effects of dietary energy levels on growth performance,carcass traits,meat quality,and serum biochemical of female Hu lambs.Seventy female Hu lambs(aged 4 months)were randomly allotted to 5 dietary treatments.Lambs were fed diets with 5 levels of metabolizable energy(ME):9.17(E1),9.59(E2),10.00(E3),10.41(E4),and 10.82 MJ/kg(E5).The lambs were adapted to the experimental diets for 10 d and the experiment period lasted for 60 d.Dry matter intake and feed conversion ratio linearly(P<0.001)increased and decreased(P<0.001),respectively,with increasing dietary ME levels.Average daily gain(ADG)linearly(P<0.001)increased with increasing dietary ME levels,with the highest final body weight(P=0.041)observed in E4 group.Moreover,dietary energy level was associated with linear increases in serum total protein(TP)(P<0.001),albumin(ALB)(P=0.017),glucose(GLU)(P=0.004),and low-density lipoprotein cholesterol(LDLC)(P=0.006)concentrations,and it was associated with a quadratic decrease in serum triglyceride(TG)concentration(P=0.002).Serum ammonia concentration,which was firstly decreased and then increased,was quadratically affected by dietary ME levels(P=0.013).Compared with E1 group,lambs in E4 group had higher(P<0.05)live weights,carcass weights,mesenteric fat ratio,non-carcass fat ratio,and larger loin muscle area,but lower(P<0.05)meat colour a*and b*values,and lesser(P<0.05)C17:0,C20:0,C18:1 n-9 t,C18:3 n-3,and n-3 polyunsaturated fatty acids(PUFA),but greater(P<0.05)C18:3 n-6 and n-6:n-3 ratios in longissimus dorsi(LD)muscle tissue,and lesser(P<0.05)C17:0,C18:3 n-3,C22:6 n-3,and n-3 PUFA in the biceps femoris(BF)muscle tissue.The results demonstrated that increasing dietary energy level improved the growth performance and affected carcass traits,serum biochemical indexes,and fatty acid profiles in different muscles of female Hu lambs.For 4-month-old female Hu lambs,the recommended fattening energy level is 10.41 MJ/kg.

Dietary supplementation of Lonicera macranthoides leaf powder improves amino acid profiles in serum and longissimus thoracis muscle of growing-finishing pigs

A 60-days feeding trial was conducted to determine the effect of dietary supplementation of Lonicera macranthoides leaf(LML) on growth performance, meat quality, and free amino acid profiles in growingfinishing pigs. L. macranthoides leaves were harvested, air-dried and milled to powder. A total of 288 crossbred barrows(Large White x Landrace) with an average initial BW of 54.0 ± 3.4 kg were randomly allocated to 3 treatment groups and fed either a basal diet or a diet supplemented with 0.5% or 1.0% LML powder. Results showed that diet supplemented with LML powder did not affect average daily feed intake(ADFI) and feed: gain ratio(P> 0.05) in growing-finishing pigs. Moreover, diet supplemented with LML powder showed no significant effects on carcass traits(P > 0.05) including dressing percentage,backfat thickness and loin muscle area, and meat quality traits(P > 0.05) including meat color, intramuscular fat and cooking loss. However, diet supplemented with LML powder significantly improved free amino acid profiles in serum and longissimus thoracis muscle in growing-finishing pigs. Most importantly, dietary LML powder increased total free amino acids content(P < 0.001) and essential free amino acid content(P < 0.001) in longissimus thoracis muscle. These results indicate that LML has the potential to improve the nutritional value of meat through improving free amino acid profiles.

Supplementation of branched-chain amino acids in protein-restricted diets modulates the expression levels of amino acid transporters and energy metabolism associated regulators in the adipose tissue of growing pigs

This experiment was conducted to investigate the effects of branched-chain amino acids(BCAA)supplemented in protein-restricted diets on the growth performance and the expression profile of amino acid transporters and energy metabolism related regulators in the white adipose tissue(WAT)of different regional depots including dorsal subcutaneous adipose(DSA) and abdominal subcutaneous adipose(ASA), A total of 24 crossbred barrows(7.40 ± 0.70 kg) were randomly divided into 4 groups and were fed the following isocaloric diets for 33 days: 1) a recommended adequate protein diet(AP, 20% CP, as a positive control); 2) a low protein diet(LP, 17% CP); 3) the LP diet supplemented with BCAA(LP + B, 17% CP) to reach the same level of the AP diet group; 4) the LP diet supplemented with 2 times the amount of BCAA(LP + 2B, 17% CP). The daily gain and daily feed intake of the LP diet group were the lowest among all the treatments(P < 0.01). The feed conversion was improved markedly in the group of LP + B compared with the LP diet group(P < 0.05). No significant difference was noted for the serum biochemical parameter concentrations of glucose, triglyceride, nonesterified fatty acid and insulin among the groups(P > 0.05). Moreover, BCAA supplementation down-regulated the expression levels of amino acid transporters including L-type amino acid transporter 1 and sodium-coupled neutral amino acid transporter 2 in DSA, but up-regulated the expression level of Ltype amino acid transporter 4 in ASA(P < 0.05), Meanwhile, the energy sensor AMP-activated protein kinase α was activated in the DSA of pigs fed LP diet and in the ASA of the pigs fed AP or LP + 2B diets(P < 0.05). The mRNA expression profile of the selected mitochondrial component and mitochondrial biogenesis associated regulators in DSA and ASA also responded differently to dietary BCAA supplementation. These results suggested that the growth performance of growing pigs fed protein restricted diets supplemented with BCAA could catch up to that of the pigs fed AP diets. The results also partly demonstrated that the regulation mechanisms of BCAA are different in the adipose tissues of different depots.

Effects of stocking density on growth performance, blood parameters and immunity of growing pigs

This study was conducted to evaluate the effects of different stocking densities on growth performance,blood parameters,intestinal morphology and intestinal immunity of growing pigs.A total of288 male pigs(44.35±0.50 kg)were randomly assigned to groups with stocking densities of 2.46,1.23 and 0.82 m2/pig for a month.The results showed that there was no significant difference on growth performance among groups.Pigs in the stocking density of 0.82 m2/pig had the lowest backfat thickness and spleen weight index among groups(P<0.05).With increasing stocking density,the serum concentrations of blood urea nitrogen(BUN),transglutaminase(TGG),alkaline phosphatase(AKP)and immunoglobulin A(Ig A)were increased,and albumin(ALB),albumin-to-globulin ratio(ALB:GLO),insulin-like growth factor-1(IGF-1)and immunoglobulin(Ig M)were decreased(P<0.05),and cortisol tended to increase and glucose tended to decrease(0.05<P<0.1).Compared with the stocking density of 2.46 m2/pig,the ileal villus height and jejunal villus width decreased in stocking densities of 1.23 and 0.82 m2/pig(P<0.05).The duodenal villus height and ileal villus width in the stocking density of 0.82 m2/pig were the lowest among 3 groups(P<0.05).The content of immunoglobulin A in duodenum,jejunum and ileum mucosa increased along with increasing density(P<0.05).The contents of interleukin(IL)-2 in the spleen or liver and IL-10 in the spleen were higher in the stocking density of 0.82 m2/pig than in other 2 groups.These results showed that stocking density could affect the metabolism,intestinal morphology,and immunity of growing pigs and 1.23 m2/pig may be the suitable stocking density for the growing pigs in the present study.

Compensation effects of coated cysteamine on meat quality, amino acid composition, fatty acid composition, mineral content in dorsal muscle and serum biochemical indices in finishing pigs offered reduced trace minerals diet

Dear Editor.Trace mineral elements(ME)and amino acids have been demonstrated to be essential bioelements in animal nutrition.If there is a deficiency in ME,a number of biological functions in animals may be affected,including physical growth,psychomotor development,and immunity.Supplementation of pig diets with ME is known to improve the animals'growth,reproduction,and their immunity against oxidative stress and cell damage.

Myokine interleukin-15 expression profile is different in suckling and weaning piglets

Interleukin-15(IL-15) is a cytokine highly expressed in skeletal muscle. The objective of the present study was to investigate the development of muscle IL-15 expression in suckling piglets and in early weaning piglets(day 14) at each level, that is, mRNA, protein, and secretion. Eight litters(eight piglets per litter) of newborn healthy piglets(Large × White × Landrace) with a similar initial weight(1618.0 ± 140.1 g) were chosen and divided into two groups, Group one used suckling piglets that were killed, respectively, at days 1,7,14,21, and group two used early(day 14) weaning piglets that were killed respectively, at days 15, 17, 19, 21. In group one, IL-15 gene expression levels increased significantly(P < 0.05) along with increased body weight over time. IL-15 protein expression levels in piglets at day 21 of age were higher(P < 0.05) than those in piglets at other ages, and there was no difference(P > 0.05)among piglets at other ages. These findings indicated that increased IL-15 mRNA expression did not result in a corresponding increase of its protein expression. In group two, which used early weaning piglets from days 15-19, IL-15 mRNA and protein expression levels increased constantly(P < 0.05) and were higher(P < 0.05) than those in suckling piglets. Moreover, there was no gain of body weight(P > 0.05) compared with suckling piglets at day 14 of age. However, IL-15 protein expression levels in early weaning piglets at day 21 of age dropped significantly(P < 0.05) to the levels as suckling piglets at day 21 of age, while body weight increased(P < 0.05) markedly to the levels as suckling piglets at day 21 of age. In both groups, the serum IL-15 levels of piglets decreased significantly(P < 0.01) over time. Taken together, our results indicate that IL-15 expression differs in suckling piglets and in weaning piglets. It is speculated that IL-15 may play an important role in counteracting the effects of early weaning stress.

Mulberry leaf powder regulates antioxidative capacity and lipid metabolism in finishing pigs

This study evaluated the potential of mulberry leaf powder as an unconventional feed material for fin-ishing pigs by assessing the growth performance,antioxidative properties,fatty acid profile,and lipid metabolism in 180 Xiangcun black pigs.Pigs with an initial body weight(BW)of 71.64±1.46 kg were randomly assigned to 5 treatment groups,including the control diet and 4 experimental diets.The corn,soybean meal,and wheat bran in the control diet were partly replaced by 3%,6%,9%,or 12%mulberry leaf powder in experimental diets.There were 6 replicates(pens)of 6 pigs per replicate in each treatment.Blood and muscle samples were collected after the 50-day feed experiment.Compared with the control group,the 3%,6%,and 9%mulberry diets had no adverse effect(P>0.05)on the growth performance of pigs.The serum glutathione peroxidase activity and glutathione concentration increased linearly(P<0.05)with the increase in dietary mulberry inclusion.There was no significant difference in the relative expression levels of antioxidant-related genes in muscle tissue between the control and mul-berry groups.Inclusion of dietary mulberry powder increased(P<0.05)the content of polyunsaturated fatty acids,especially in the longissimus dorsi(LD)muscle,up-regulated(P<0.05)the relative mRNA expression level of uncoupling protein-3 in muscle tissue,but down-regulated(P<0.05)the relative mRNA expression levels of hormone-sensitive lipase,acetyl CoA carboxylaseα,lipoprotein lipase,and peroxisome proliferator-activated receptor y in LD in a linear pattern.The nuclear respiratory factor 2 expression level in the LD muscle of pigs fed the 9%mulberry diet was higher(P<0.01)than that in the other mulberry groups and control group.The inclusion of less than 12%dietary mulberry did not detrimentally affect the growth performance of Xiangcun black pigs,but enhanced the serum antioxidant property,increased the polyunsaturated fatty acid content,and inhibited lipid oxidation by regulating gene expression levels of lipid metabolism and mitochondrial uncoupling protein in muscle tissue.Mulberry leaves can be utilized as a forage crop in the diet of finishing pigs.

Low-protein diets supplemented with glutamic acid or aspartic acid ameliorate intestinal damage in weaned piglets challenged with hydrogen peroxide

Glutamic acid(Glu)and aspartic acid(Asp)are acidic amino acids with regulatory roles in nutrition,energy metabolism,and oxidative stress.This study aimed to evaluate the effects of low-protein diets supplemented with Glu and Asp on the intestinal barrier function and energy metabolism in weaned piglets challenged with hydrogen peroxide(H2O2).Forty piglets were randomly divided into 5 groups:NC,PC,PGA,PG,and PA(n=8 for each group).Pigs in the NC and PC groups were fed a low-protein diet,while pigs in the PGA,PG,or PA groups were fed the low-protein diet supplemented with 2.0%Glu+1.0%Asp,2.0%Glu,or 1.0%Asp,respectively.On day 8 and 11,pigs in the NC group were intraperitoneally injected with saline(1 mL/kg BW),while pigs in the other groups were intraperitoneally administered 10%H2O2(1 mL/kg BW).On day 14,all pigs were sacrificed to collect jejunum and ileum following the blood sample collection in the morning.Notably,low-protein diets supplemented with Glu or Asp ameliorated the intestinal oxidative stress response in H2O2-challenged piglets by decreasing intestinal expression of genes(P<0.05)(e.g.,manganese superoxide dismutase[MnSOD],glutathione peroxidase[Gpx]-1,and Gpx-4)encoding oxidative stress-associated proteins,reducing the serum concentration of diamine oxidase(P<0.05),and inhibiting apoptosis of the intestinal epithelium.Glu and Asp supple-mentation attenuated the upregulated expression of energy metabolism-associated genes(such as hexokinase and carnitine palmitoyltransferase-1)and the H2O2-induced activation of acetyl-coenzyme A carboxylase(ACC)in the jejunum and adenosine monophosphate-activated protein kinase-acetyl-ACC signaling in the ileum.Dietary Glu and Asp also ameliorated intestinal barrier damage as indicated by restored intestinal histology and morphology.In conclusion,low-protein diets supplemented with Glu and Asp protected against oxidative stress-induced intestinal dysfunction in piglets,suggesting that this approach could be used as a nutritional regulatory protectant against oxidative stress.

Dietary butyrate,lauric acid and stearic acid improve gut morphology and epithelial cell turnover in weaned piglets

This study was to evaluate the effects of the supplementation of saturated fatty acids with different chain lengths on growth performance,intestinal morphology,epithelial cell proliferation,differentiation and apoptosis in weaned piglets.Thirty-two weaned piglets(Duroc×Landrace×Yorkshire,BW=7.81±0.26 kg)were weaned at 21 d and randomly assigned to 1 of 4 experimental treatments:(1)a basal diet(control);(2)control+0.3% butyrate(BT);(3)control+0.3%lauric acid(LA);(4)control+0.3% stearic acid(SA).All piglets were then slaughtered for tissue sampling after having been fed experimental diets for 28 d after weaning.Supplementation of BT increased the gain-to-feed ratio(G:F)(P<0.05)compared to piglets fed the control diet from 14 to 28 d.In addition,the villus height(VH)to crypt depth(CD)ratio(VH:CD ratio)of the ileum were higher in the BT and LA diets than that of the control diet(P<0.05).The SA-supplemented diet increased ileal VH(P<0.05),whereas the BT-supplemented diet increased jejunal CD(P<0.05).Compared to the control,diets supplemented with BT,LA,or SA all tended to increase jejunal proliferation(Ki67/crypt positive cells)(P=0.190);diets supplemented with BT or SA significantly increased the number of ki67-positive cells in the ileal crypt(P<0.05).Furthermore,in the jejunum,the protein expression of activated caspase 3 and villin were increased in piglets fed BT,LA,or SA diets compared to those on the control diet(P<0.05).In the ileum,compared with the control diet,the BT diet tended to increase the protein level of mammalian phosphorylation target of rapamycin(p-m TOR,P<0.10);LA or SA diets significantly increased p-m TOR protein expression(P<0.05).These results show that dietary supplementation of BT,LA,or SA promotes jejunal cell renewal in weaned piglets.At the same time,increased proliferation of ileal crypt cells by promoting p-m TOR expression has beneficial effects on ileal morphology in weaned piglets.