Protein intake, sources and distribution impact on muscle protein synthesis and muscle mass in older adults. However, it is less clear whether dietary protein influences muscle strength. Data were obtained from the Researching Eating Activity and Cognitive Health (REACH) study, a cross-sectional study aimed at investigating dietary patterns, cognitive function and metabolic syndrome in older adults aged 65–74 years. Dietary intake was assessed using a 4-d food record and muscle strength using a handgrip strength dynamometer. After adjusting for confounders, in female older adults (n 212), total protein intake (β = 0⋅22, P < 0⋅01); protein from dairy and eggs (β = 0⋅21, P = 0⋅03) and plant food sources (β = 0⋅60, P < 0⋅01); and frequently consuming at least 0⋅4 g/kg BW per meal (β = 0⋅08, P < 0⋅01) were associated with higher BMI-adjusted muscle strength. However, protein from meat and fish intake and the coefficient of variance of protein intake were not related to BMI-muscle strength in female older adults. No statistically significant associations were observed in male participants (n = 113). There may be sex differences when investigating associations between protein intake and muscle strength in older adults. Further research is needed to investigate these sex differences.

Depression is an important public health problem. The aim of the study is to explore the associations of total protein intake and protein sources with the risk of depressive symptoms. This cross-sectional study used data from the National Health and Nutrition Examination Survey for the years 2007–2014. Dietary protein intake was obtained from two 24-h dietary recall interviews. Depressive symptoms were assessed by a nine-item Patient Health Questionnaire. Logistic regression models and restricted cubic spline models were used to estimate the associations of total protein intake (g/kg per d) and protein sources with the risk of depressive symptoms. A total of 17 845 individuals aged 18 years and older were included in this study. Total protein intake was inversely associated with the risk of depressive symptoms. The full-adjusted OR of depressive symptoms was 0·34 (95 % CI 0·17, 0·68) for quartile (Q) 4 v. Q1 of total protein intake. For protein intake from milk and milk products, the association with depressive symptoms was significant both for Q2 v. Q1 (OR 0·61; 95 % CI 0·41, 0·93) and Q3 v. Q1 (OR 0·37; 95 % CI 0·24, 0·59) in the full-adjusted model. In the dose–response analysis, the shape of the associations of total protein intake and protein intake from milk and milk products with the risk of depressive symptoms was approximately L-shaped and U-shaped, respectively. The present study demonstrated that total protein intake and protein intake from milk and milk products might reduce the risk of depressive symptoms in US adults.

The increasing global need to find alternative protein/energy sources has triggered research in the field of non-conventional feed ingredients, with insects and former foodstuffs being the most promising. Insects contain high level of protein and fat, whereas former foodstuffs contain high energy in the form of carbohydrates and fats; therefore, both should be considered as promising alternative feed ingredients for livestock production. In addition to the nutritional value, they also represent a way by which food waste biomasses/streams can be upgraded to valuable feed ingredients. This review outlines the main nutritional and safety issues of insects and former foodstuffs, and also considers the legal framework involved. The importance of the type of insect metamorphosis and tailored substrates that could lead to the production of a premium feed is also described. This is also the first time that a review discusses the nutritional quality of former foodstuffs. Energy and the main nutrient content of former foodstuff are compared with the composition of common cereals as the principal energy sources in animal feed. For both ingredients a critical review of the safety issues is provided. Based on the current data available, both insects and former foodstuffs have an excellent potential use as alternative feed ingredients for livestock production. When produced in line with the criteria set by major feed/food authorities, they are characterized by high quality and safety standards. This makes them comparable to other feed materials and ingredients currently available on the market, although their full nutritional, functional, safety and sustainability evaluation cannot be considered complete.

The study investigated whether different dietary energy and protein sources affect laying performance, antioxidant status, fresh yolk fatty acid profile and quality of salted yolks in laying ducks. In all, 360 19-week-old Longyan ducks were randomly assigned to four diets in a factorial arrangement (2×2). The four diets consisted of two energy sources, corn (CO) or sorghum (SO) and two protein sources, soybean meal (SM) and rapeseed meal with corn distillers dried grains with solubles (RMD), and each treatment contained six replicates of 15 birds each. The experimental diets were isocaloric (metabolizable energy, 10.84 MJ/kg) and isonitrogenous (CP, 17%). The results showed that egg production, average egg weight, egg mass and feed conversion ratio were not affected by diets (P>0.05). Plasma contents of reduced glutathione (GSH), GSH/oxidized glutathione and total antioxidant capacity were lower (P<0.05) in ducks fed the RMD diets compared with those fed SM diets with a substantial increase (P=0.006) in plasma content of malondialdehyde (MDA). Egg yolks from ducks fed SO diets had higher proportions of polyunsaturated fatty acids (PUFA) and lower saturated and monounsaturated fatty acids compared with CO diets (P<0.001). Similarly, ducks fed RMD diets had a higher content of PUFA and n-6/n-3 ratio in fresh yolks (P<0.001), and increased salted yolk MDA, carbonylated proteins content and incidence of hard salted yolks (P<0.05) compared with SM diets. Scanning electron microscopy showed that salted yolks contained rougher polyhedral granules and fewer fat droplets, and were surrounded with a layer of bunchy fibers in ducks fed SO+RMD than those fed CO+SM diet. In conclusion, the current study showed that feeding laying ducks with diets containing SO or RMD reduced antioxidant capacity and increased egg yolk concentrations of PUFA. It appeared that egg yolks from ducks fed these diets were more sensitive to lipid peroxidation and protein oxidation during salting, and reduced the quality of salted yolks.

The population of the Middle East and North Africa (MENA) region was 432 million in 2007 and it is estimated that in 2050 this figure will rise to 692 million inhabitants. The poultry industry in the MENA region depends heavily on imported soybeans and soybean meals. About 8.5 million metric tons of soybean meal (SBM) are needed for the production of poultry meat and eggs every year, based on the production of about 8.2 million tons of poultry meat and 3.7 million tons of eggs. Poultry feed prices are consistently increasing because of dependence on imported soybean meal. Hence, it is essential to find sustainable alternative protein sources. Several countries in the region produce sizeable amounts of oil seed meals that can partially or fully replace soybean meal in poultry rations. Nearly 5 million tons of cottonseed meal (CSM), peanut meal, sesame meal, sunflower meal and rapeseed meal are produced yearly in this region. The neighbouring countries of India, Pakistan and Sudan produce over 36 million tons of these meals. This study focused on these five meals in relation to amounts produced, quality and possible levels of use in various poultry rations. Data will be presented on availability, constraints of these meals as replacements for SBM, economic feasibility, and methods of improvement for possible utilisation at higher levels. Oil seed meal digestibility, quality, naturally occurring toxins, antimetabolites, mycotoxins, nutrient imbalances, and prices play a major role in determining the use of these meals for the production of poultry meat and eggs.

An experimental, microbially enhanced soybean product (MEPRO) was evaluated as a replacement for fishmeal (FM). Assessment of feedstuffs should include estimation of digestibility as well as pig performance and in combination with dietary additives. Digestibility values determined in growing pigs may not apply to nursery pigs; thus, standardized ileal digestibility (SID) of amino acids (AA) in MEPRO and FM were determined using 30±1.6 kg BW ileal-cannulated barrows (n=6) and 9.8±1.2 kg BW barrows (n=37; serial slaughter). Experimental diets included MEPRO, FM and nitrogen free where FM and MEPRO were included as the sole protein source. The SID of AAs was 3% to 5% lower in MEPRO than FM when fed to 30 kg pigs. The SID of arginine and methionine was greater (P<0.05) in MEPRO than FM when fed to 10 kg pigs. The SID of AAs was 12% to 20% lower in FM when fed to 10 v. 30 kg pigs but only 3% to 9% lower in MEPRO. A total of 336 barrows and gilts were weaned at 21 days of age (initial BW=6.1±0.8 kg) and used in a performance trial. Pens of pigs were assigned to one of the six experimental diets (8 pens/diet in two blocks). Treatment diets were fed in Phase I (7 days) and Phase II (14 days) with all pigs fed a common Phase III diet (14 days). Experimental diets included (1) negative control (NEG) containing corn, soybean meal and whey, (2) NEG+acidifier, (3) NEG+FM (POS), (4) POS+acidifier (POS A+), (5) NEG+MEPRO (MEPRO) and (6) MEPRO+acidifier. The FM and MEPRO were included at 7.5% and 5.0% in Phase I and II diets, respectively. Diets were formulated to meet the standard nutrient requirements for weaned pigs. Pig BW and feed disappearance was measured weekly and fecal scores were measured daily for the first 14 days post-weaning as an indicator of post-weaning diarrhea syndrome (PWDS). Performance (BW, daily gain, feed intake and gain : feed) was not significantly different among treatments. Treatment for PWDS occurred on different days in each block. Analysis of fecal score was completed separately by block. Pigs fed the NEG diets had higher (P=0.02) fecal scores than pigs fed the POS diets on days 2 and 3 (block 1) and higher (P<0.05) than pigs fed MEPRO or POS diets and diets with dietary acidifier on days 6 and 3 (block 2). The MEPRO holds promise as an alternative to FM in nursery pig diets.

Diet composition may affect blood pressure (BP), but the mechanisms are unclear. The aim of the present study was to compare postprandial BP-related responses to the ingestion of pea protein, milk protein and egg-white protein. In addition, postprandial BP-related responses to the ingestion of maltodextrin were compared with those to the ingestion of sucrose and a protein mix. We hypothesised that lower postprandial total peripheral resistance (TPR) and BP levels would be accompanied by higher plasma concentrations of nitric oxide, insulin, glucagon-like peptide 1 (GLP-1) and glucagon. On separate occasions, six meals were tested in a randomised order in forty-eight overweight or obese adults with untreated elevated BP. Postprandial responses of TPR, BP and plasma concentrations of insulin, glucagon, GLP-1 and nitrite, nitroso compounds (RXNO) and S-nitrosothiols (NOx) were measured for 4 h. No differences were observed in TPR responses. Postprandial BP levels were higher after the ingestion of the egg-white-protein meal than after that of meals containing the other two proteins (P≤ 0·01). The ingestion of the pea-protein meal induced the highest NOx response (P≤ 0·006). Insulin and glucagon concentrations were lowest after the ingestion of the egg-white-protein meal (P≤ 0·009). Postprandial BP levels were lower after the ingestion of the maltodextrin meal than after that of the protein mix and sucrose meals (P≤ 0·004), while postprandial insulin concentrations were higher after the ingestion of the maltodextrin meal than after that of the sucrose and protein mix meals after 1–2 h (P≤ 0·0001). Postprandial NOx, GLP-1 and glucagon concentrations were lower after the ingestion of the maltodextrin meal than after that of the protein mix meal (P≤ 0·008). In conclusion, different protein and carbohydrate sources induce different postprandial BP-related responses, which may be important for BP management. Lower postprandial BP levels are not necessarily accompanied by higher NOx, insulin, glucagon or GLP-1 responses.

Two Latin square design experiments investigated the relationship between hydrogen sulphide concentration in the rumen headspace gas of dairy cows and the early stages of protein degradation in the rumen. In Expt 1, three protein sources differing in rumen N (nitrogen) degradability (maize gluten feed (MGF); sunflower meal (SFM); and soyabean meal (SBM)) were used, whereas in Expt 2 four different batches of the same feed (MGF) differing in colour (CIE L*, a*, b* (CIELAB) scale) were used. After allowing the concentration of hydrogen sulphide in rumen gas to decline close to zero, a fixed amount of protein sources was offered to cows and the concentrations of hydrogen sulphide were recorded in rumen headspace gas at 30-min intervals. In Expt 1, the concentration of hydrogen sulphide showed considerable variation between protein sources, with MGF having the highest concentration followed by SFM and SBM resulting in very low concentrations. The N wash losses (zero time measurements with nylon bags) ranked the feeds in the same way, from MGF (highest; 61%) to SBM (lowest; 26%). There were marked differences in the degradation of cystine and methionine between protein sources, although the degradation of cystine was always higher than for methionine. MGF (Expt 2) led to increased concentrations of hydrogen sulphide, with peak concentrations achieved between 1 and 2 h after feeding. The concentrations of hydrogen sulphide were higher for MGF1, intermediate for MGF2 and lower for MGF3 and MGF4, agreeing with colour scale. Differences in the early stages of dietary sulphur degradation corresponded with differences in hydrogen sulphide concentrations in rumen gas. The results suggest that hydrogen sulphide concentrations in the rumen headspace gas could be useful to evaluate nutritional parameters not measured by the in sacco technique, contributing to a better understanding of the response of dairy cows to different protein supplements.

The aim of this work was to study the effect of protein source / availability on the intestinal microbiota, digestive traits and nutritional performance of early-weaned rabbits. The effects of supplemental antibiotics in the drinking water were also evaluated. Four isoenergetic and isofibrous diets were formulated: a control diet with a high protein (207 g/kg dry matter (DM)) and lucerne hay content (HPHL), a diet with low crude protein (CP) (179 g/kg DM) and high lucerne hay content (LPHL) and low protein diets in which the lucerne hay in diet LPHL was replaced partially (LPML) or totally (LPLL) with soya-bean protein concentrate. Rabbits, weaned at 25 days (52 per diet), were fed the experimental diets for a 2-week period and thereafter received a commercial diet until 56 days of age. The incidence of mortality was investigated using 70 animals per diet without supplemental medication. The profile of the ileal microbiota was studied at 35 days of age in rabbits treated (18 per diet) or not (12 per diet) with antibiotic. As expected, supplementation with antibiotics effectively reduced fattening mortality rate and microbial biodiversity. However, lowering of also the dietary CP content led to a reduction in the mortality rate ( P < 0.05), both in animals treated with (by 80%) or without (by 39%) antibiotics. In addition, there was a reduction ( P < 0.05) in the frequency of Clostridium perfringens in non-medicated animals. Neither jejunal morphology nor growth performance, over the whole fattening period, was affected by dietary CP content of the experimental diets. However, with HPHL, feed efficiency was higher (by 4.8%; P < 0.01) than with LPHL diets. Substitution of lucerne hay with soya-bean meal in low protein diets did not affect apparent faecal or ileal digestibility of DM and CP. However, the ileal digestibility of cystine, alanine, aspartic acid, and proline was lowered ( P < 0.05) with increasing substitution by soya bean. Nevertheless, ileal CP flow, incidence of mortality and presence of C. perfringens were unaffected. Our results suggest that a reduction in dietary CP, resulting in reduced lumenal flows of nitrogen through the ileum, may be beneficial for young rabbits and limit the numbers of potentially harmful bacteria in the lower gut. Modulation of dietary CP should be contemplated as a strategy to increase the intestinal health in rabbits.

Four ewes fitted with ruminal and duodenal T-piece cannulae were each given six diets in a 6 × 4 factorial design. Diets or experimental treatments consisted of two ratios of forage: concentrate (700:150 (LC) and 400: 600 (HO). Forage was ammonia-treated straw and the concentrate was formulated with barley supplemented with one of three protein sources: sunflower meal, soya-bean meal or fish meal. Duodenal flows ofdigesta were estimated by the dual-phase technique using Co-EDTA and Yb acetate as liquid and solid markers. Microbial nitrogen (N) was estimated from the digesta flow of purine bases and 15N enrichment using as reference samples, bacterial isolates from the liquid (LAB) or solid (SAB) phase of rumen digesta.

Duodenal flow of purine bases (mmol/day) was lower on LC (12·9) than HC (17·7) diets but in both treatments it was depressed by fish meal (12·3) compared with either soya-bean (17·3) or sunflower meal (16·3) as supplements (s.e. 1·13). Urinary excretion of purine derivatives showed a similar trend, 8·6 v. III mmol/day in LC and HC respectively and 8·8 v. 10·4 and 10·5 mmol/day in fish meal, soya-bean and sunflower meal diets (s.e. 0·56), respectively. Variation in excretion of urinary purine derivatives was mainly associated with digestible organic matter intake with an average ratio of 1·7 (s.e. 0·11) mmol per 100 g digestible organic matter intake. Irrespective of the microbial marker used, microbial yield was higher in animals offered HC than in those offered LC and with soya-bean or sunflower meal compared with fish meal supplemented diets. The microbial purine bases/N (mmol/g) ratio varied between LAB (1·99, s.e. 0·092) and SAB (1·69, s.e. 0·071) isolates leading to different estimates of microbial-N yield (g) from duodenal purine bases (7·76 (s.e. 2·84) v. 9·13 (s.e. 3·24)), urinary excretion of allantoin (5·57 (s.e. 2·0) v. 6·57 (s.e. 2·03)) or total purine derivatives (6·43 (s.e. 2·39) v. 7·56 (s.e. 2·77)). Urinary excretion of allantoin or total purine derivatives provided consistently lower estimates of duodenal microbial-N than duodenal purine bases or 15N, although it closely reflected the pattern observed in direct measurements.

Two experiments were carried out to evaluate extracted soya-bean meal, fish meal and maize gluten feed as protein supplements for calves offered grass silage ad libitum. The five treatments used in experiment 1 consisted of 1·4 kg per head daily of concentrate dry matter (DM) consisting of (g/kg) 50 molasses and 25 minerals and vitamins plus (1) 925 barley (B), (2) 700 B and 225 extracted soya-bean meal (SBM), (3) 785 B and 140 fish meal (FM), (4) 925 maize gluten feed (MGF) and (5) 2·25 kg DM per head daily of concentrate (1). Those used in experiment 2 consisted of 1·4 kg per head daily of concentrate DM consisting of (g/kg) (1) 1000 B, (2) 800 B and 200 SBM, (3) 860 B and 140 FM, (4) 1000 MGF and (5) 2·25 kg DM per head daily of B. In each experiment the diets were offered to 70 calves which were initially 131 and 130 kg live weight, for periods of 14 and 13 weeks in experiments 1 and 2 respectively. The silages contained 155 and 154 g crude protein (CP) per kg DM; 45 and 77 g ammonia-nitrogen per kg total nitrogen and 698 and 726 g digestible organic matter per kg DM in experiments 1 and 2. Concentrates 1 and 5 contained 104 to 110 g CP per kg DM and concentrates 2, 3 and 4 contained 195 to 204 g CP per kg DM in both experiments. For diets 1 to 5 respectively silage DM intakes were 2·31,2·50,2·53,2·59 and 1 -61 (s.e. 0·097) kg/day; live-weight gains were 0·84,0·98,1 -01, 0·88 and 0·95 (s.e. 0·032) kg/day in experiment 1 and 2·38, 2·53, 2·54, 2·82 and 1·77 (s.e. 0·045) kg/day and 0·90,1·04,1·03,1·05 and 0·99 (s.e. 0·038) kg/day for experiment 2. It is concluded that the use of soya-bean meal rather than fish meal did not affect silage intake or animal performance. Replacing mixtures of barley and soya-bean meal or barley and fish meal with an equal quantity of isonitrogenous maize gluten feed did not affect animal performance in one experiment but significantly reduced it in the other experiment.