Effect of supplementing lysins and methionine to low-protein diets on growth performance, hepatic antioxidant capacity, immune status, and glycolytic activity of tibetan sheep.

Reducing the levels of dietary protein is an effective nutritional approach in lowering feed cost and nitrogen emissions in ruminants. The purpose of this study was to evaluate the effects of dietary Lys/Met ratio in a low protein diet (10%, dry matter basis) on the growth performance and hepatic function (antioxidant capacity, immune status, and glycolytic activity) in Tibetan lambs. Ninety two-month-old rams with an average weight of 15.37 ± 0.92 kg were randomly assigned to LP-L (dietary Lys/Met = 1:1), LP-M (dietary Lys/Met = 2:1) and LP-H (dietary Lys/Met = 3:1) treatments. The trial was conducted over 100 d, including 10 d of adaption to the diets. Hepatic phenotypes, antioxidant capacity, immune status, glycolytic activity and gene expression profiling was detected after the conclusion of the feeding trials. The results showed that the body weight was higher in the LP-L group when compared to those on the LP-M group (P < 0.05). In addition, the activities of the catalase (CAT) and glutathione peroxidase (GSH-Px) in the LP-L group were significantly increased compared with the LP-M group (P < 0.05), while the malondialdehyde (MDA) levels in LP-H group were significantly decreased (P < 0.05). Compared with LP-H group, both hepatic glycogen (P < 0.01) and lactate dehydrogenase (LDH) (P < 0.05) were significantly elevated in LP-L group. For the LP-L group, the hepatocytes were arranged radially with the central vein in the center, and hepatic plates exhibited tight arrangement. Transcriptome analysis identified 29, 179, and 129 differentially expressed genes (DEGs) between the LP-M vs. LP-L, LP-H vs. LP-M, and LP-H vs. LP-L groups, respectively (Q-values < 0.05 and |log2Fold Change| > 1). Gene Ontology (GO) and correlation analyses showed that in the LP-L group, core genes (C1QA and JUNB) enriched in oxidoreductase activity were positively correlated with antioxidant indicators, while the MYO9A core gene enriched in the immune response was positively associated with immune indicators, and core genes enriched in molecular function (PDK3 and PDP2) were positively correlated with glycolysis indicators. In summary, low-protein diet with a low Lys/Met ratio (1:1) could reduce the hepatic oxidative stress and improve the glycolytic activity by regulating the expression of related genes of Tibetan sheep.

Effects of essential amino acids supplementation in a low-protein diet on growth performance, intestinal health and microbiota of juvenile blotched snakehead (Channa maculata).

Developing a low-protein feed is important for the sustainable advancement of aquaculture. The aim of this study was to investigate the effects of essential amino acid (EAA) supplementation in a low-protein diet on the growth, intestinal health, and microbiota of the juvenile blotched snakehead, Channa maculata in an 8-week trial conducted in a recirculating aquaculture system. Three isoenergetic diets were formulated to include a control group (48.66 % crude protein (CP), HP), a low protein group (42.54 % CP, LP), and a low protein supplementation EAA group (44.44 % CP, LP-AA). The results showed that significantly lower weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), and feed efficiency ratio (FER) were observed in fish that were fed LP than in the HP and LP-AA groups (P < 0.05). The HP and LP-AA groups exhibited a significant increase in intestinal villus length, villus width, and muscular thickness compared to the LP group (P < 0.05). Additionally, the HP and LP-AA groups demonstrated significantly higher levels of intestinal total antioxidant capacity (T-AOC), catalase (CAT), and superoxide dismutase (SOD) and lower levels of malondialdehyde (MDA) compared to the LP group (P < 0.05). The apoptosis rate of intestinal cells in the LP group was significantly higher than those in the LP and HP groups (P < 0.05). The mRNA expression levels of superoxide dismutase (sod), nuclear factor kappa B p65 subunit (nfκb-p65), heat shock protein 70 (hsp70), and inhibitor of NF-κBα (iκba) in the intestine were significantly higher in the LP group than those in the HP and LP-AA groups (P < 0.05). The 16s RNA analysis indicated that EAA supplementation significantly increased the growth of Desulfovibrio and altered the intestinal microflora. The relative abundances of Firmicutes and Cyanobacteria were positively correlated with antioxidant parameters (CAT and T-AOC), whereas Desulfobacterota was negatively correlated with sod and T-AOC. The genera Bacillus, Bacteroides, and Rothia were associated with the favorable maintenance of gut health. In conclusion, dietary supplementation with EAAs to achieve a balanced amino acid profile could potentially reduce the dietary protein levels from 48.66 % to 44.44 % without adversely affecting the growth and intestinal health of juvenile blotched snakeheads.

Effects of rumen-encapsulated methionine and lysine supplementation and low dietary protein on nitrogen efficiency and lactation performance of dairy cows.

Low crude protein (CP) diets might be fed to dairy cows without affecting productivity if the balance of absorbed AA were improved, which would decrease the environmental effect of dairy farms. The aim of this study was to investigate the effects of supplementing ruminally protected Lys (RPL) and Met (RPM) at 2 levels of dietary CP on nutrient intake, milk production, milk composition, milk N efficiency (MNE), and plasma concentrations of AA in lactating Holstein cows and to evaluate these effects against the predictions of the new NASEM (2021) model. Fifteen multiparous cows were used in a replicated 3 × 3 Latin square design with 21-d periods. The 3 treatments were (1) a high-protein (HP) basal diet containing 16.4% CP (metabolizable protein [MP] balance of -130 g/d; 95% of target values), (2) a medium-protein diet containing 15% CP plus RPL (60 g/cow per day) and RPM (25 g/cow per day; MPLM; MP balance of -314 g/d; 87% of target values), and (3) a low-protein diet containing 13.6% CP plus RPL (60 g/cow per day) and RPM (25 g/cow per day; LPLM; MP balance of -479 g/d; 80% of target values). Dry matter intake was less for cows fed MPLM and LPLM diets compared with those fed the HP diet. Compared with the HP diet, the intake of CP, neutral detergent fiber, acid detergent fiber, and organic matter, but not starch, was lower for cows fed MPLM and LPLM diets. Milk production and composition were not affected by MPLM or LPLM diets relative to the HP diet. Milk urea N concentrations were reduced for the MPLM and LPLM diets compared with the HP diet, indicating that providing a low-protein diet supplemented with rumen-protected AA led to greater N efficiency. There was no significant effect of treatment on plasma AA concentrations except for proline, which significantly increased for the MPLM treatment compared with the other 2 treatments. Overall, the results supported the concept that milk performance might be maintained when feeding lactating dairy cows with low CP diets if the absorbed AA balance is maintained through RPL and RPM feeding. Further investigations are needed to evaluate responses over a longer time period with consideration of all AA rather than on the more aggregated MP and the ratio between Lys and Met.

Use of wheat dilution to improve digestive function in broilers: application in low protein diets.

1. This study evaluated the effect of wheat dilution increasing in particle size in low crude protein diets on growth performance, digestive tract, nitrogen efficiency and litter quality in broiler chickens.2. Ross 308 male broiler chicks (n = 336) were allocated to one of four dietary treatments (each with 7 pens, 12 chicks per pen); Control (CON; commercial pellet diet with standard crude protein, CP: 22.50%), W578 (CON +20% wheat of geometric mean diameter (GMD) of 578 µm; CP: 20.25%), W1326 (CON +20% wheat of GMD 1326 µm; CP: 20.25%) and WW (CON +20% whole wheat, CP: 20.25%), from d 0 to 21 of age.3. Body weight gain was increased (P < 0.05) for birds fed CON compared to the low crude protein diets. However, WW increased (P < 0.05) body weight gain compared to W578 and W1326, while feed intake and feed conversion ratio on CON and WW were similar (P > 0.05). Birds fed W1326 showed the poorest (P < 0.05) FCR compared to CON, W578 and WW.4. Gizzard relative weight (g/kg body weight) was increased (P < 0.05) on WW compared to CON on d 14 and 21, whereas gastric isthmus diameter was significantly reduced on W1326 and WW compared with CON and W578.5. There were no differences (P > 0.05) in the depth of gizzard mucosa of lamina propria between CON and WW at d 14 and 21. Birds fed WW increased (P < 0.05) gizzard tensile strength compared to W578 and W1326, whereas no difference was observed between WW and CON on d 14.6. No significant differences were seen for ileum villus height and mucosal layer between CON and WW on d 21, however, feeding CON increased the extent of the mucosal layer compared to W578 and W1326.7. Nitrogen excretion (g/kg BWG) was significantly lower (P > 0.05) on W1326 and WW compared with CON and W578. Litter nitrogen, moisture, and footpad scores significantly decreased (P < 0.05) for birds fed WW compared with CON.8. Diluting dietary protein content from 22.50 to 20.25% resulted in lower body weight gain in broilers. However, dilution with whole wheat resulted in comparable FCR, reduced nitrogen excretion, litter moisture and footpad dermatitis compared with a standard protein diet.

Effects of low protein diets on acid-base balance, electrolyte balance, intestinal structure, and amino acid transport in piglets.

Reducing the dietary crude protein (CP) could effectively reduce pressure on protein ingredient supplies. However, few data have been reported about the extent to which CP can be reduced and whether limiting the use of soybean meal leads to electrolyte imbalance. In this experiment, using the low protein (LP) diet [2% lower than NRC (2012)], seventy-two piglets (35 days old) were randomly divided into 2 groups with 6 replicates of 6 piglets each: CON group (CP = 18.5%) and LP group (CP = 16.5%), to investigate the effect of the LP diet on electrolyte balance, acid-base balance, intestinal structure and amino acid transport in piglets. The results revealed that the LP diet decreased the average daily gain and dietary CP digestibility, and damaged the villi structure of the small intestine. Compared with the CON diet, the potassium content decreased and the chlorine content increased in the LP diet, and similar trends were shown in piglet serum. The arterial pH, pCO2, HCO3 -, and base excess of piglets in the LP group were lower than those in the CON group, while pO2 was higher than those in the CON group. Interestingly, the LP diet significantly increased the lysine content in piglet serum and significantly decreased the levels of arginine, leucine, and glutamic acid. Furthermore, the LP diet significantly affected the expression of some amino acid transport vectors (B0AT1, EAAC1, and y+LAT1). In summary, these findings suggested that the LP diet leads to acid-base imbalance, amino acid transport disorder and amino acids imbalance in piglets, and the dietary electrolyte may be a key factor in the impact of the LP diet on piglet growth performance and intestinal health.

Effect of supplementing rumen-protected methionine, lysine, and histidine to low-protein diets on the performance and nitrogen balance of dairy cows.

Lowering the dietary protein content can reduce N excretions and NH3 emissions from manure and increase milk N efficiency of dairy cows. However, milk yield (MY) and composition can be compromised due to AA deficiency. Methionine and Lys are known as first limiting EAA for dairy cows, and recently His is also mentioned as limiting, especially in grass-based or low-protein diets. To examine this, a trial was conducted with a 3-wk pre-experimental adaptation period (diet 16.5% crude protein), followed by a depletion period of 4 wk, in which 39 cows (average ± standard deviation: 116 ± 29.3 d in milk, 1.8 ± 1.2 lactations, 638 ± 73.2 kg of body weight, and 32.7 ± 5.75 kg MY/d) received a low-protein diet (CTRL) (14.5% crude protein). Then, taking into account parity, His plasma concentration, and MY, cows were randomly assigned to 1 of 3 treatment groups during the rumen-protected (RP) AA period of 7 wk; (1) CTRL; (2) CTRL + RP-Met + RP-Lys (MetLys); (3) CTRL + RP-Met + RP-Lys + RP-His (MetLysHis). Products were dosed, assuming requirements for digestible (d) Met, dLys, and dHis being, respectively, 2.4%, 7.0%, and 2.4% of intestinal digestible protein. In the cross-back period of 5 wk, all cows received the CTRL diet. During the last week of each period, a N balance was conducted by collecting total urine and spot samples of feces. Total feces production was calculated using the inert marker TiO2. Statistical analysis was performed with a linear mixed model with cow as random effect and data of the last week of the pre-experimental period used as covariate for the animal performance variables. No effect of supplementing RP-Met and RP-Lys nor RP-Met, RP-Lys, and RP-His on feed intake, milk performance, or milk N efficiency was observed. However, the plasma AA profile indicated additional supply of dMet, dLys, and dHis. Nevertheless, evaluation of the AA uptake relative to the cow's requirements showed that most EAA (exclusive Arg and Thr) were limiting over the whole experiment. Only dHis was sufficiently supplemented during the RP-AA period due to an overestimation of the diet's dMet and dLys supply in the beginning of the trial. The numerically increased milk urea N and urinary N excretion when RP-Met, RP-Lys, and RP-His were added to the low-protein diet suggest an increased catabolism of the excess His.

Dose response to postruminal urea in lactating dairy cattle.

Inclusion of urea in dairy cattle diets is often limited by negative effects of high levels of feed urea on dry matter intake (DMI) and efficiency of rumen N utilization. We hypothesized that supplying urea postruminally would mitigate these limitations and allow greater inclusion of urea in dairy cattle diets. Four rumen-fistulated Holstein-Friesian dairy cows (7 ± 2.1 lactations, 110 ± 30.8 d in milk; mean ± standard deviation) were randomly assigned to a 4 × 4 Latin square design to examine DMI, milk production and composition, digestibility, rumen fermentation, N balance, and plasma constituents in response to 4 levels of urea continuously infused into the abomasum (0, 163, 325, and 488 g/d). Urea doses were targeted to linearly increase the crude protein (CP) content of total DMI (diet plus infusion) by 0%, 2%, 4%, and 6% and equated to 0%, 0.7%, 1.4%, and 2.1% of expected DMI, respectively. Each 28-d infusion period consisted of a 7-d dose step-up period, 14 d of adaptation, and a 7-d measurement period. The diet was fed ad libitum as a total mixed ration [10.9% CP, 42.5% corn silage, 3.5% grass hay, 3.5% wheat straw, and 50.5% concentrate (dry matter basis)] and was formulated to meet 100%, 82%, and 53% of net energy, metabolizable protein, and rumen-degradable protein requirements, respectively. Linear, quadratic, and cubic effects of urea dose were assessed using polynomial regression assuming the fixed effect of treatment and random effects of period and cow. Dry matter intake and energy-corrected milk yield responded quadratically to urea dose, and milk urea content increased linearly with increasing urea dose. Apparent total-tract digestibility of CP increased linearly with increasing urea dose and ruminal NH3-N concentration responded quadratically to urea dose. Mean total VFA concentration was not affected by urea dose. The proportion of N intake excreted in feces decreased linearly and that excreted in urine increased linearly in response to increasing urea dose. The proportion of N intake excreted in milk increased linearly with increasing urea dose. Urinary urea excretion increased linearly with increasing urea dose. Microbial N flow responded cubically to urea dose, but the efficiency of microbial protein synthesis was not affected. Plasma urea concentration increased linearly with increasing urea dose. Regression analysis estimated that when supplemented on top of a low-CP diet, 179 g/d of postruminal urea would maximize DMI at 23.4 kg/d, corresponding to a dietary urea inclusion level of 0.8% of DMI, which is in line with the current recommendations for urea inclusion in dairy cattle diets. Overall, these results indicate that postruminal delivery of urea does not mitigate DMI depression as urea dose increases.

Effects of low protein diet with a balanced amino acid pattern on growth performance, meat quality and cecal microflora of finishing pigs.

BACKGROUND: The present study aimed to investigate the effects of low protein diets balanced with four amino acids on growth performance, meat quality and cecal microflora of finishing pigs. Fifty-four healthy hybrid barrows (Duroc × Landrace × Yorkshire) with an average body weight of 70.12 ± 4.03 kg were randomly assigned to one of the three dietary treatments with six replicate pens per treatment (three barrows per pen). The three dietary treatments included a normal protein diet (NP), a low protein diet (LP) and a very low protein diet (VLP). RESULTS: The average daily gain, average daily feed intake and feed conversion ratio of pigs were not significantly changed with the LP and VLP diets compared to the NP diet (P > 0.05). The water holding capacity and shear force of longissimus dorsi muscle were decreased, whereas the intramuscular fat content of the longissimus dorsi muscle was increased (P < 0.05) in pigs fed with the LP and VLP diets compared to the NP diet. The contents of saturated fatty acids in muscle were decreased (P < 0.05), whereas the content of polyunsaturated fatty acids in muscle was increased (P < 0.01) with the VLP diet compared to the NP diet. The contents of histamine, spermidine, spermine and tyramine of muscle were decreased with the VLP diet compared to the NP diet (P < 0.05). The relative abundance of Turicibacter, Terrisporobacter, Clostridium_sensu_stricto_1 and UCG-005 was higher (P < 0.05), whereas the relative abundance of Lactobacillus and Streptococcus was lower (P < 0.05) in pigs fed with the LP and VLP diets compared to the NP diet. Based on the correlation of cecal microbiota and cecal biogenic amine, the contents of tyramine, spermidine and histamine were negatively correlated with the abundance of Terrisporobacter (P < 0.01) and the content of histamine was positively correlated with the abundance of Lactobacillus (P < 0.01). CONCLUSION: Balanced with four essential amino acids, the VLP diet with crude protein levels decreased by > 4% increased the intramuscular fat content, changed the fatty acid and amino acid composition of longissimus dorsi muscle and the profile of cecum microbiota, and reduced the content of cecum bioamine, with no negative effect on the growth performance of pigs. © 2022 Society of Chemical Industry.

Determination of standardised ileal digestibility of amino acids in high-fibre feedstuffs and additivity of apparent and standardised ileal amino acids digestibility of diets containing mixtures of maize, sorghum, and soybean meal.

1. Two experiments were conducted to determine the coefficients of standardised ileal amino acid digestibility for selected high-fibre feedstuffs (Expt.1) and to assess the additivity of coefficients of apparent (cAIAAD) and standardised (cSIAAD) ileal amino acid digestibility for diets containing combinations of sorghum, maize and soybean meal.2. In Expt. 1, broiler chickens (324) were allocated to 54 metabolism cages (nine diets with six replicates). In Expt. 2, broiler chickens (315) were allocated to 63 metabolism cages (seven diets with nine replicates). The diets in Expt. 1 were a nitrogen-free diet plus eight semi-purified diets in which soybean meal (SBM), low-protein SBM (LPSBM), soybean hull, wheat bran, maize bran, rice bran, dried sugarbeet pulp or maize gluten feed were the only sources of protein in the respective diets. In Expt. 2, the seven diets were a nitrogen-free diet, and six semi-purified diets consisting of individual feedstuffs (SBM, maize, or sorghum) or combinations (maize and SBM; sorghum and SBM; or maize, sorghum, and SBM) as the only sources of protein.3. In both experiments, all the broiler chickens received the same maize-SBM diet formulated to meet nutrient requirements according to the breeder's recommendations from d 0 to 16. Allocated experimental diets were provided on d 16, and ileal digesta were collected on d 21.4. In Expt. 1, SBM and LPSBM had greater (P < 0.01) cSIAAD for indispensable and dispensable amino acids than the other feedstuffs. The rice bran had greater (P<0.01) cSIAAD values than wheat bran and maize bran, except for Leu, Cys, and Pro.5. In Expt. 2, predicted cAIAAD values for maize-SBM and maize-sorghum-SBM were generally lower (P<0.01) than actual values. The actual and predicted cSIAAD values for maize-SBM, sorghum-SBM and maize-sorghum-SBM combinations were not significantly different.6. It was concluded that the standardised amino acid digestibility of sorghum, when combined with other feedstuffs, was additive and that approximately three-quarters of total amino acids in the assayed high-fibre feedstuffs, except for dried sugarbeet pulp and maize gluten feed, were digestible.

Digestibility and nitrogen balance of goats on high and low protein rations supplemented with a commercial tannin feed-additive.

Despite the increasing importance of goat production in response to high demand for their products and their relative robustness to environmental stressors, and in contrast to other ruminant species, little data is available on how tannin extract feeding affects their feed intake, nutrient digestion and nitrogen (N) metabolism. Therefore, a trial in Oman investigated the respective variables by using a commercial tannin feed additive. In a 4 (treatments) x 3 (periods) x 2 (animals) Youden square, two weaned Batinah bucks each were fed a high or low protein diet of Rhodes grass hay and crushed barley grain, with or without the addition of a chestnut and quebracho tannin extract at 2 g/kg metabolic weight. Feed offered, feed refused and faeces and urine excreted were quantified to determine diet digestibility, total N excretion, N retention and rumen microbial protein synthesis (MPS). Due to their young age and low live weight, feed intake of goats was relatively low. Crude protein level and tannin addition had no statistically significant effect on dry matter (DM) and N intake, DM digestibility, N excretion in faeces and urine, as well as MPS. In consequence, no benefit of tannin feeding could be confirmed for the goats' N retention, irrespective of diet composition. These results indicate, on one hand, an effective neutralisation of the tested tannin extract along the gastrointestinal tract of goats, but on the other hand, that stimulation of MPS or N retention by tannins cannot be evidenced when diet components are present that simultaneously release energy and protein, as is the case with barley.

Effect on growth performance, carcass traits, and myostatin gene expression in Aseel chicken fed varied levels of dietary protein in isocaloric energy diets.

A study was conducted to assess the effect of feeding different crude protein (CP) levels with isocaloric metabolizable energy (ME) diets on growth performance, carcass traits, and myostatin (MSTN) gene expression of Aseel chicken during 0 to 16 weeks of age. A total of two hundred and ten day-old Aseel chickens were randomly allotted to seven dietary treatment groups. Each group had thirty chicks distributed into three replicates of ten chicks in each. Experimental diets were formulated to have varying levels of CP, viz. 18.5, 19.0, 19.5, 20.0, 20.5, 21.0, and 21.5%, with isocaloric energy of 2800 kcal ME/kg diets of mash feed fed to birds in a completely randomized design. Different CP levels had a significant effect (P < 0.05) on the body weight gain (BWG) of Aseel chicken. At the end of 16 weeks of age, the group fed 21% CP gained 223.53 g more than the lowest CP (18.5%)-fed group. The different CP levels did not significantly (P > 0.05) influenced the feed intake of all treatment groups, but numerically highest feed intake was observed in the lowest CP (18.5%)-fed group. However, significant differences in feed efficiency (FE) appeared from the 13th week only with the 21.0% CP-fed group showing the best FE until the 16th week (3.86 to 4.06). The maximum dressing % (70.61) was observed by the 21% CP-fed group. The CP 21% diet down-regulated the MSTN gene expression in breast muscle tissue to 0.07 folds when compared to the diet of CP 20%. The best economical coordinates for maximum performance for Aseel chicken appeared to be CP of 21% and ME of 2800 kcal/kg to achieve the best FE of 3.86 at the earliest age of 13 weeks. In conclusion, 21% CP in an isocaloric diet of 2800 kcal ME/kg, in Aseel chickens, would be optimum to improve the growth performance at maximum in terms of BWG and FE up to 16 weeks of age.

Effect of exogenus protease on performance, nutrient digestibility, intestinal histomorphometric, meat quality characteristics, carcass yield in broilers fed low protein diets.

The objective of the present study was to evaluate the effects of increasing doses of protease on broilers from 1 to 42 days of age. A total of 1290 Ross AP broilers were used, distributed among five treatments: positive control diet, negative control diet (NC), NC + 50 ppm of protease, NC + 100 ppm of protease, and NC + 200 ppm of protease. Each treatment contained six replicates of 43 animals each. The inclusion of proteases in the diet had effects (P < 0.05) on body weight, feed intake, weight gain, and feed conversion in the 12 to 21 day period; body weight, weight gain, and feed intake in the 29 to 42 day period; nutrient digestibility (energy metabolizability coefficient and crude protein at 28 days); and intestinal parameters (crypt and muscle width of jejunum and ileum at 28 days and villus length, crypt length, and jejunum thickness muscle layer at 42 days). These results indicate that the inclusion of protease in broiler feed can improve production parameters when the amount of crude protein in the diet is reduced.

Milk production and efficiency of utilization of nitrogen, metabolizable protein, and amino acids are affected by protein and energy supplies in dairy cows fed alfalfa-based diets.

Alfalfa has a lower fiber digestibility and a greater concentration of degradable protein than grasses. Dairy cows could benefit from an increased digestibility of alfalfa fibers, or from a better match between nitrogen and energy supplies in the rumen. Alfalfa cultivars with improved fiber digestibility represent an opportunity to increase milk production, but no independent studies have tested these cultivars under the agroclimatic conditions of Canada. Moreover, decreasing metabolizable protein (MP) supply could increase N use efficiency while decreasing environmental impact, but it is often associated with a decrease in milk protein yield, possibly caused by a reduced supply of essential AA. This study evaluated the performance of dairy cows fed diets based on a regular or a reduced-lignin alfalfa cultivar and measured the effect of energy levels at low MP supply when digestible His (dHis), Lys (dLys), and Met (dMet) requirements were met. Eight Holstein cows were used in a double 4 × 4 Latin square design, each square representing an alfalfa cultivar. Within each square, 4 diets were tested: the control diet was formulated for an adequate supply of MP and energy (AMP_AE), whereas the 3 other diets were formulated to be deficient in MP (DMP; formulated to meet 90% of the MP requirement) with deficient (94% of requirement: DMP_DE), adequate (99% of requirement: DMP_AE), or excess energy supply (104% of requirement; DMP_EE). Alfalfa cultivars had no significant effect on all measured parameters. As compared with cows receiving AMP_AE, the dry matter intake of cows fed DMP_AE and DMP_EE was not significantly different but decreased for cows fed DMP_DE. The AMP_AE diet provided 103% of MP and 108% of NEL requirements whereas DMP_DE, DMP_AE, and DMP_EE diets provided 84, 87, and 87% of MP and 94, 101, and 107% of NEL requirements, respectively. In contrast to design, feeding DMP_EE resulted in a similar energy supply compared with AMP_AE, although MP supply has been effectively reduced. This resulted in a maintained milk and milk component yields and improved the efficiency of utilization of N, MP, and essential AA. The DMP diets decreased total N excretion, whereas DMP_AE and DMP_EE diets also decreased milk urea-N concentration. Reducing MP supply without negative effects on dairy cow performance is possible when energy, dHis, dLys, and dMet requirements are met. This could reduce N excretion and decrease the environmental impact of milk production.

Effects of supplementation of graded level of glutamic acid to crude protein reduced diets on the performance of growing pigs.

A total of 150 growing pigs ([Landrace × Yorkshire] × Duroc) with an initial average body weight (BW) of 24.45 kg were used in a 6-week trial to estimate the optimum lysine to glutamic acid ratio in pigs fed low-protein diets supplemented with increasing level of synthetic glutamic acid (Glu). Pigs were randomly allotted to 5 dietary treatments consisting of either control diet (CON) formulated to have 157 g crude protein (CP) or negative control diets (NC, NC1, NC2 and NC3) with 20 g CP reduction and addition of Glu (1.1, 3.9, 6.8 and 9.6 g/kg feed respectively). Supplementing the increasing level of Glu to low CP diets did not exert any linear or quadratic responses in the growth performance parameters as well as nutrient digestibility. The serum creatinine concentration in pigs receiving CON diet showed trends (p = 0.063) in increment compared with pigs receiving NC diet. However, with the increase in the supplementation of Glu, there were no linear or quadratic responses on serum blood urea nitrogen (BUN) and creatinine concentrations. There was a tendency in the reduction (p = 0.088, p = 0.064) of backfat thickness and lean percentage, respectively, at week 3 and a trend in the reduction (p = 0.092) in lean percentage at week 6 in pigs fed NC diet compared with those fed CON diet. The increase in the supplemental level of Glu tended to show quadratic responses in the backfat thickness and lean percentage at week 3 and 6. In conclusion, the growth performance parameters as well as carcass traits with Lys: Glu ratio 1: 2.71 were very close with the mean values of CON diet indicating that 6.8 g Glu when supplemented to 2% CP reduced diet could achieve the comparable growth performance and carcass trait as that of standard basal diet.

Dietary lysine supplementation improves growth performance and skeletal muscle development in rabbits fed a low protein diet.

The purpose of this study was to investigate the effects on growth of Lysine (Lys) supplementation in a low protein diet. We also investigated the gene or protein expression related to skeletal muscle development and intestinal amino acid transporters, and determined the major signalling associated with Lys-regulating skeletal muscle development. 1000 healthy, weights averaging 938.6 ± 6.54 g weaned rabbits were randomly divided into five groups (five replicates in each group and 40 rabbits in each replicate). These groups consisted of the normal protein group (NP group, consuming a diet containing 16.27% protein), the low protein group (LP group, 14.15%-14.19% protein) and the LP group with an addition of 0.15%, 0.3% or 0.45% Lys. The trial included 7 d of pre-feeding and 28 d of exposure to the treatment. Compared with NP diet and LP diet, LP+0.3% Lys group improved growth performance (p < 0.05), full-bore weight and half-bore weight of rabbits (p < 0.05). The LP+0.3% Lys group also resulted in a decrease in the excretion of faecal nitrogen and urinary nitrogen (FN; UN; p < 0.05), and an increase in nitrogen utilisation rate (NUR; p < 0.05). LP diet increased the mRNA expression of MSTN and WWP1, and decreased the mRNA expression of IGF1 (p < 0.05). LP diet decreased the protein expression of P-P70S6K1, P-4EBP1 and P-S6 (p < 0.05). LP+0.3% Lys group attenuated the effects of LP diet on the expression of MSTN, WWP1, IGF1, P-P70S6K1, P-4EBP1 and P-S6 (p < 0.05). LP+0.3% Lys group resulted in an increase in mRNA expression of MyoD and protein expression of P-mTOR relative to the NP and LP groups (p < 0.05). In summary, the addition of Lys to a LP diet provides a theoretical basis for the popularisation and application of Lys in rabbit production.

Sepiolite as an effective supplement for low-protein diets with the constant energy-protein ratio in broilers.

The present study aimed to examine the influence of sepiolite on growth performance, meat quality, intestinal health, some blood parameters, and digestibility of nutrients in broilers fed low-protein diets with the constant energy-protein ratio. A total of 252, daily male broiler chicks were allocated to four treatment groups further divided into 9 replicates each containing 7 chicks. Low-protein diets having a constant energy-protein ratio were formulated by lowering protein and energy levels of the control group diet by 5%. Sepiolite was used at the level of 1% in the diets. After 42 days of trial, total feed consumption, total body weight gain, total feed conversion ratio, and carcass yield were not influenced by reducing protein, sepiolite supplementation, and interaction between low-protein-low-energy diet and sepiolite. Reducing protein in the diets led to reducing the digestibility of nutrients, increasing ileal viscosity, decreasing villus height, villus surface area in duodenum and jejunum, and increasing abdominal fat and ether extract, cooking losses, total oxidant status, and oxidative status index in breast meat. Sepiolite supplementation to low-protein diets increased crude protein digestibility, reduced viscosity, increased villus height/crypt depth values and reduced cooking losses, and increased water holding capacity in breast meat. Blood serum biochemical parameters and minerals were not affected by sepiolite supplementation to low-protein diets. Therefore, it is concluded that sepiolite can be added as a beneficial supplement in broiler diets as well as in low-protein diets with a constant energy-protein ratio.

Interactive effects of high temperature and crude protein levels on growth performance, nitrogen excretion, and fecal characteristics of broilers.

In the present study, we aimed to explore the interactive effects of high temperature (HT) and dietary crude protein (CP) levels on nitrogen (N) excretion, fecal characteristics, and growth performance of broilers. A total of 288 broilers (Arbor Acres) were divided into six groups with eight replicates (six broilers per replicate). Two temperatures (ambient temperature: AT, 23 °C; HT: 28 ~ 32 ~ 28 °C) and three diets (CP: 14.90%, 18.18%, or 21.19%, with equal amounts of essential amino acids) were examined in a 2 × 3 factorial design. The experiment arrangement was from 4 to 6 weeks of age. The results showed that HT led to a significant decrease in the N excretion (P < 0.0001), average daily feed intake (P < 0.0001), and weight gain of broilers (P < 0.0001), while it markedly increased the fecal pH (P = 0.015), fecal moisture (P = 0.0014), uric acid (UA) contents (P = 0.0018), and feed/gain ratio (P < 0.0001). A low CP diet significantly decreased the N excretion (P < 0.001), fecal pH (P = 0.016), fecal moisture (P < 0.0001), and UA contents (P < 0.0001), while it markedly increased the feed/gain ratio (P < 0.001). In conclusion, HT had a negative impact on the fecal characteristics and growth performance of broilers but showed positive effects on N excretion. Moreover, decreased CP levels had a positive effect on the N excretion and fecal characteristics in broilers.

Effect of composite enzyme supplementation on production parameters, intestinal segment measurements, and apparent nutrient digestibility of broiler chickens fed low energy and protein diets.

A 42-day study was conducted to consider the effect of composite enzyme (Natuzyme®) supplementation on production parameters, intestinal segment measurements, and nutrient digestibility of broiler chickens fed low energy and protein (LEP) diets. Two hundred male Ross 308 broiler chicks consisting of 4 groups were divided into five pens (10 chicks/pen). The first group (control) received a standard diet without composite enzyme (CE) supplementation, whereas the LEP0, LEP0.25, and LEP0.50 groups received LEP supplemented with CE at 0, 0.25, and 0.50 g/kg feed, respectively. Compared to birds in the control group, supplementation of 0.50 g/kg CE to LEP diet offset (P < 0.05) the poor feed intake (FI), body weight gain (BWG), feed conversion ratio (FCR), and cost/kg gain observed among LEP0 and LEP0.25 groups on days 0-21, 22-42, and 0-42. Birds in the LEP0, followed by the LEP0.25 group, had decreased (P < 0.05) ileum weight, villi height, villus height, and crypt depth ratio (VH/CD), and deeper crypt depth of duodenum and ileum compared to birds in the control group. However, the aforementioned parameters were improved in the LEP0.50 group. Likewise, supplementation of CE at 0.50 g/kg to broiler diet having LEP improved (P < 0.05) digestibility of energy, fiber, and protein on day 42. In conclusion, CE supplemented at 0.50 g/kg diet ameliorated the negative effect caused by feeding LEP diets on production parameters, ileum weight, villi height, VH/CD, and deeper crypt depth of duodenum and ileum as well as energy, fiber, and protein digestibility of broiler chickens.

Direct and maternal reduced balanced protein diet influences the liver transcriptome in chickens.

The objective of this study was to evaluate, by means of RNA sequencing, the direct and transgenerational effect of a reduced balanced protein (RP) diet on broiler breeder metabolism. Chickens of the F0 generation were fed a control (C) or RP diet, and their F1 progeny was fed a C or RP diet as well, resulting in four groups of chickens: C/C, C/RP, RP/C and RP/RP. While both direct and maternal effects were seen on body weight, breast muscle weight and abdominal fat weight in the F1 generation, the direct effect was the most dominant one. The liver transcriptome in the F1 generation showed that amino acid metabolism was up-regulated in chickens that received the control feed when compared with their respective contemporaries that received the reduced protein diet. Interestingly, chickens hatched from control-fed hens but reared on the reduced protein diet (C/RP group) activated a fatty acid metabolism, expressing more fatty acid desaturase 1 gene, fatty acid desaturase 2 gene and elongation of very long-chain fatty acids protein 2 gene, when compared with control-fed chickens hatched from control-fed hens (C/C group), while chickens hatched from reduced protein-fed hens that received themselves the same reduced protein diet (RP/RP group) triggered their glucose metabolism more, showing elevated levels of phosphofructokinase gene, 6-phosphofructo-2-kinase/fructose-2,6-biphospatase 4 and fructose-biphosphate aldolase C mRNA compared with the chickens hatched from reduced protein-fed hens but reared on a control diet (RP/C group). This suggests that the maternal protein diet has an impact on the metabolism of broilers when they are reared on a RP diet.

Dietary starch level and rumen-protected methionine, lysine, and histidine: Effects on milk yield, nitrogen, and energy utilization in dairy cows fed diets low in metabolizable protein.

Our objective was to investigate the interactions between starch level and rumen-protected Met, Lys, His (RP-MLH) on milk yield, plasma AA concentration, and nutrient utilization in dairy cows fed low metabolizable protein diets (mean = -119 g/d of metabolizable protein balance). Sixteen multiparous Holstein cows (138 ± 46 d in milk, 46 ± 6 kg/d in milk) were used in a replicated 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Dietary starch level varied by replacing (dry matter basis) pelleted beet pulp and soyhulls with ground corn resulting in the following treatments: (1) 20% pelleted beet pulp and 10% soyhulls (reduced starch = RS), (2) RS plus RP-MLH (RS+AA), (3) 30% ground corn (high starch = HS), and (4) HS plus RP-MLH (HS+AA). Dietary starch concentrations averaged 12.3 and 34.4% for RS and HS basal diets, respectively. Diets were supplemented with RP-MLH products to supply digestible Met, Lys, and His. Compared with RS and RS+AA diets, HS and HS+AA diets increased yields of milk (37.9 vs. 40.1 kg/d) and milk protein (1.07 vs. 1.16 kg/d) and decreased dry matter intake (25.9 vs. 25.2 kg/d), milk urea N (12.6 vs. 11.0 mg/dL), and plasma urea N (13.3 vs. 11.6 mg/dL). Milk N efficiency was greater in cows fed the HS and HS+AA than RS and RS+AA diets (28.9 vs. 25%), and RP-MLH supplementation improved milk true protein concentration. Starch level × RP-MLH interactions were observed for plasma concentrations of Arg and Lys, with RP-MLH being more effective to increase plasma Arg (+16%) and Lys (+23%) when supplemented to the RS than the HS basal diet. Replacing pelleted beet pulp and soyhulls with ground corn lowered the plasma concentrations of all essential AA except Met and Thr. In addition, the plasma concentrations of His and Met increased with RP-MLH. The apparent total-tract digestibilities of neutral and acid detergent fiber were lower, and those of starch and ether extract greater in cows offered the HS and HS+AA diets than RS and RS+AA diets. Urinary excretion of urea N decreased by replacing pelleted beet pulp and soyhulls with ground corn. Enteric CH4 production, CH4 yield, and CH4 intensity all decreased in the HS and HS+AA versus RS and RS+AA diets. Diets did not affect the intakes of gross energy, metabolizable energy, and net energy of lactation. In contrast, digestible energy intake increased with feeding the RS and RS+AA diets, whereas CH4 energy decreased in cows fed the HS and HS+AA diets. Supplementation with RP-MLH had no effect on energy utilization variables. Overall, the lack of interactions between dietary starch level and RP-MLH supplementation on most variables measured herein showed that the effects of starch intake and RP-MLH were independent or additive.