Dietary Crude Protein Content Research Articles

Meta-analysis of the effects of prepartum dietary protein on performance of dairy cows

The objectives were to review the published literature and use meta-analytic methods to determine the effects of dietary protein fed prepartum on productive performance of dairy cows. The hypothesis was that responses to dietary protein prepartum would differ between nulliparous and parous cows, and performance would be maximized at a greater protein supply in nulliparous than in parous cows. The literature was systematically reviewed, searching randomized experiments in which the prepartum dietary content or degradability of protein was manipulated. Twenty-seven experiments including 125 treatment means and 1,801 cows were included in the meta-analysis. Of those, 8 experiments with 27 treatment means reported responses for 510 nulliparous cows. Data collected included the ingredient composition and chemical analyses of prepartum diets, parity group, and means and respective measures of variance for productive responses. Mixed model meta-analysis was conducted and statistical models investigated the effects of dietary crude protein (CP) or supply of metabolizable protein (MP) prepartum on performance. Supply of MP was predicted using the National Research Council Nutrient Requirements of Dairy Cattle (2001) model. The mean ± standard deviation and median (range) concentrations of dietary CP fed to cows prepartum were 14.4 ± 2.2 and 14.4% (8.9 to 20.9%), resulting in mean and median (range) intakes of CP prepartum of 1,720 ± 432 and 1,734 g/d (745 to 2,482 g/d). Predicted prepartum supply of MP averaged 822 ± 157 in nulliparous cows, ranging from 517 to 1,094 g/d, and 1,146 ± 316 in parous cows, ranging from 463 to 1,733 g/d. Increasing prepartum CP content or predicted supply of MP improved postpartum dry matter intake in nulliparous cows, but increasing prepartum CP content reduced prepartum dry matter intake in parous cows. Yields of milk and fat-corrected milk increased with increasing prepartum supply of MP in nulliparous but not in parous cows. Yields of fat and protein increased in nulliparous cows with increased CP content or supply of MP. Alternatively, in parous cows, yield of milk fat was not influenced by supply of MP but responded quadratically to dietary CP content and was maximized at approximately 14% CP. Dietary CP had no effect on protein yield in parous cows, but increasing the supply of MP improved protein yield only in cows from experiments with >36 kg/d of milk production, whereas MP supply had no effect on protein yield of parous cows from experiments with <28 kg/d of milk production. Performance of dairy cows was responsive to prepartum supply of MP and nulliparous benefited from diets with increased MP intake. Based on current results, production responses for nulliparous cows increased linearly up to the maximum MP intake of 1,100 g/d observed in the study, whereas for parous cows, only yield of milk protein in cows producing more than 36 kg of milk/d was influenced by supplying more than 800 g/d of MP.

Effects of dietary butyrate supplementation and crude protein level on carcass traits and meat composition of broiler chickens.

The short-chain fatty acid butyrate, either in unprotected or protected form, is widely applied as a growth-promoting feed additive in poultry nutrition; however, its possible effects on the carcass composition of broilers have not been fully elucidated. Further, lowering dietary crude protein (CP) levels is an important issue in poultry farming, contributing to ecologically beneficial lower nitrogen excretion. The main aims of this study were to test how unprotected and protected forms of butyrate and decreased dietary CP content with essential amino acid (lysine, methionine, threonine, tryptophan) supplementation (“LP-EAA” diet) affect carcass parameters and the chemical composition of muscles in broilers. Ross 308 chickens were randomized to seven groups (/group) receiving adequate CP-containing (normal protein, “NP”) or LP-EAA diets, both supplemented with or without unprotected sodium butyrate, and NP diets with different forms of protected sodium butyrate. Carcass traits were measured, and the chemical composition of pectoral and femoral muscles was analyzed at the age of 6 weeks. Carcass weight was significantly increased by the LP-EAA diet and all protected butyrate types tested, while the relative breast meat yield was significantly higher in LP-EAA than NP groups and in both unprotected and protected butyrate-supplemented chickens compared to controls. The protein content of the femoral muscle was significantly decreased, but its lipid content was significantly elevated by the LP-EAA diet and by all types of butyrate addition. However, no changes were detected in the chemical composition of pectoral muscle. In conclusion, breast meat production can be effectively stimulated by dietary factors, such as by reducing dietary CP content with essential amino acid supplementation and by applying butyrate as a feed additive, while its chemical composition remains unchanged, in contrast to the femoral muscle. The aforementioned nutritional strategies seem to be the proper tools to increase carcass yield and to alter meat composition of broilers, contributing to more efficient poultry meat production.

Environmental impacts of pig production systems using European local breeds: The contribution of carbon sequestration and emissions from grazing

Abstract Environmental assessment of pig production systems using local breeds remains poorly documented in the literature. So far, studies did not account for specificities of outdoor rearing which is quite common in such systems. The present study aimed at evaluating the environmental impacts of pig production systems using local breeds in Europe, while accounting for emissions associated to consumption of grass and mitigation of impacts through soil-C sequestration. Environmental impacts were estimated for 48 farms using local pig breeds: 25 in France (Gascon breed), eight in Italy (Mora Romagnola breed) and 15 in Slovenia (Krskopolje breed). Assessment was performed with and without accounting for pasture-intake emissions and potential soil-C sequestration. The data were obtained from on-farm surveys. Systems with Gascon pigs had the lowest impacts per kg of live weight for global warming and cumulative energy demand, due to lower impacts of feeds. Acidification potential was higher for Krskopolje pigs due to high dietary crude protein content and high AP of feeds, while eutrophication potential was higher for Gascon pigs due to higher phosphorus content of feeds (28% higher than the mean of the other farms). When impacts were expressed per ha of land use, pig production in Gascon farms had the lowest impacts due to more available area per pig, except for eutrophication. Low contribution of soil-C sequestration to climate change mitigation was observed (4.7% on average). However, it may have a substantial contribution for the most extensive pig systems using large land surfaces. Emissions resulting from grazing had a rather low contribution to Global Warming Potential (4%) and Eutrophication (3%), but a substantial one to Acidification impact (9% on average). In the frame of our study, the contribution of emissions related to grazing is moderate because commercial feed supply for outdoor pigs was higher than in extensive systems studied in literature. This study highlighted that main hotspots include feed composition and supply and the origin of feed ingredients. It also suggests that future assessments of extensive pig systems relying on pig foraging on grasslands or rangelands should account for soil-C sequestration and emissions associated to grazing and foraging.

Oscillating and static dietary crude protein supply. I. Impacts on intake, digestibility, performance, and nitrogen balance in young Nellore bulls.

: Effects of dietary crude protein (CP) supply on intake, digestibility, performance, and N balance were evaluated in young Nellore bulls consuming static or oscillating CP concentrations. Forty-two young bulls (initial BW of 260 ± 8.1 kg; age of 7 ± 1.0 mo) were fed ad libitum and were randomly assigned to receive one of six diets with different CP concentrations for 140 d: 105 (LO), 125 (MD), or 145 g CP /kg DM (HI), and LO to HI (LH), LO to MD (LM), or MD to HI (MH) oscillating CP at a 48-h interval for each feed. At the end of the experiment, bulls were slaughtered to evaluate carcass characteristics. Linear and quadratic effects were used to compare LO, MD, and HI, and specific contrasts were applied to compare oscillating dietary CP treatments vs. MD (125 g CP/kg DM) static treatment. Dry matter intake (DMI) was not affected (P > 0.26) by increasing or oscillating dietary CP. As dietary N concentration increased, there was a subsequent increase in apparent N compounds digestibility (P = 0.02), and no significant difference (P = 0.38) was observed between oscillating LH and MD. Daily total urinary and fecal N increased (P < 0.01) in response to increasing dietary CP. Significant differences were observed between oscillating LM and MH vs. MD, where bulls receiving the LM diet excreted less (P < 0.01; 71.21 g/d) and bulls fed MH excreted more (P < 0.01) urinary N (90.70 g/d) than those fed MD (85.52 g/d). A quadratic effect was observed (P < 0.01) for retained N as a percentage of N intake, where the bulls fed LO had greater N retention than those fed HI, 16.20% and 13.78%, respectively. Both LH and LM had greater (P < 0.01) daily retained N when compared with MD. Performance and carcass characteristics were not affected (P > 0.05) by increasing or oscillating dietary CP. Therefore, these data indicate that although there is no alteration in the performance of growing Nellore bulls fed with oscillating CP diets vs. a static level of 125 g CP/kg DM, nor static low (105 g CP/kg DM) and high (145 g CP/kg DM) levels; there may be undesirable increases in environmental N excretion when the average dietary CP content is increased. The results suggest that dietary CP concentrations of 105, 125 g/kg DM, or within this range can be indicated for finishing young Nellore bulls, since it reaches the requirements, reduces the environmental footprint related to N excretion, and may save on costs of high-priced protein feeds.

Effects of Feeding Low Protein Diets on Serum and Faeces Parameters in Weaned Piglets

Abstract This study was conducted to determine the effects of a low-protein diet supplemented with synthetic amino acids on the biochemical parameters in the blood serum, the indicators of fermentation processes, and nitrogen excretion in 12 crossbred piglets. The piglets (weaned at 28 days of age) were divided into two groups with 6 piglets each. The control group had an initial average body weight of 8.8 ± 0.6 kg and the experimental group with an average initial body weight of 8.6 ± 0.7 kg. The control diet contained 210.8 g.kg−1 crude protein and the experimental diet contained 186.4 g.kg−1. The experimental diet was supplemented with lysine, methionine and threonine to achieve a more ideal amino acid pattern. The blood collections from the sinus ophthalmicus for the determination of the biochemical parameters were performed 4 times at weekly intervals in the control and experimental groups 4—5 hours after feeding. The faeces were taken from the rectum at the end of the study period. The decrease in the dietary crude protein content of the experimental group was manifested by a significant decrease of the blood urea level (2.61 mmol.l−1 average concentration) compared to the control groups (4.21 mmol.l−1 average concentration) (P &lt; 0.001). The other serum component concentrations (total protein, albumin, glucose, cholesterol, total lipids and selected enzymes) showed no significant statistical changes between the control and experimental groups. The results of the fermentation process analysis indicated that the butyrate concentration decreased (P = 0.0017) and the pH increased (P = 0.0180) in the experimental group compared to the control group. The levels of crude protein and ammonia in the faeces of experimental animals were significantly lower (P &lt; 0.001) in comparison with those in the control animals.

Dietary Nutritive Value, Dung Quality, Decomposition, and Nutrient Movement into Soil in Smooth Bromegrass Pastures

Legumes increase forage nutritive value in pastures; however, literature addressing the impacts on dietary nutritive value, dung quality, decomposition, and nutrient movement into soil remains scarce. Cattle grazing legume‐interseeded smooth bromegrass (Bromus inermis Leyss.) pastures may select diets with greater nutritive value and consequently produce dung that decomposes faster and increases nutrient movement into soil relative to cattle grazing N‐fertilized and unfertilized smooth bromegrass pastures. In 2014 and 2015, we collected rumen and dung samples from replicated experiments to evaluate effects of season (June and August), pasture type (legume‐interseeded, N‐fertilized, and unfertilized pastures), and harvest time (3, 7, and 30 d after deposition) on dietary nutritive value, dung quality, dung decomposition, and nutrient movement into soil. Cattle grazing legume‐interseeded pastures had similar dietary crude protein concentrations but 11% less dietary neutral detergent fiber concentrations than cattle grazing N‐fertilized pastures. Dung from cattle grazing legume‐interseeded pastures, meanwhile, had 5 to 12% greater N concentrations than dung from cattle grazing N‐fertilized and unfertilized pastures. From 3 to 30 d after deposition, dung C/N ratio decreased from 20.0 to 16.5; whereas, dry matter remaining diminished to 77.5%. Dung C/N ratio and dry matter remaining did not vary with season or pasture type. At Day 7, soil below dung from cattle grazing legume‐interseeded pastures had 20 and 42% greater inorganic N than soil below dung from N‐fertilized and unfertilized pastures. This research showed that pastures with legumes increases dietary nutritive value, resulting in greater dung quality and increased N movement into soil.

Effects of reducing dietary content of crude protein and indispensable amino acids on performance and carcass traits of single-phase- and 2-phase-fed growing-finishing pigs

Effects of reducing dietary content of crude protein (CP) and Lys on performance and carcass traits of growing-finishing pigs were studied in 690 crossbred (Swedish Yorkshire dams x Hampshire sires) female and vaccinated entire male pigs with an average initial live weight (LW) of 32.3 kg. The pigs were raised in pens with mixed sexes and were fed restrictedly using 2 different feeding plans, single-phase and 2-phase. Within each feeding plan, 3 CP contents were investigated: 13.5 (low), 14.5 (medium), and 15.5 (high) g standardized ileal digestible (SID) CP/g SID Lys. Each CP comprised 2 Lys contents. For single-phase-fed pigs this implied either 0.76 or 0.85 g SID Lys/MJ net energy (NE). For 2-phase-fed pigs, the contents were either 0.89 in phase 1 and 0.71 in phase 2 or 0.98 in phase 1 and 0.79 in phase 2 g SID Lys/MJ NE. In low and high Lys, the expected total consumption of digestible Lys from start to slaughter was calculated to be equal for single-phase- and 2-phase-fed pigs. The change of diet in the 2-phase feeding plan was at an average LW of 60.8 kg and slaughter was performed at 117.3 kg. Irrespective of dietary CP and Lys content, 2-phase-fed pigs had higher daily weight gain (DWG) and better feed conversion in phase 1 than single-phase-fed pigs. In phase 2, single-phase-fed pigs fully compensated, so that overall DWG and feed conversion did not differ between single-phase- and 2-phase-fed pigs (1014 vs. 1013 g/d; 24.5 vs. 24.5 MJ NE/kg DWG). Dietary CP content had no effect on DWG and feed conversion in phase 1. However, pigs grew faster and had better feed conversion in phase 2 (P = 0.002 and P = 0.018, respectively) and during the entire raising period with the high CP content (P = 0.003 and P = 0.006, respectively). For both single-phase- and 2-phase-fed pigs, high dietary Lys content improved DWG and feed conversion in phase 1 compared with the low content (1002 vs. 968 g/d; P = 0.001 and 20.7 vs. 21.5 MJ NE/kg DWG; P = 0.004), whereas no difference was observed in phase 2. Overall, Lys content did not affect DWG, while feed conversion was better for pigs fed the high Lys content (P = 0.035). Carcass traits were unaffected by feeding plan, CP, and Lys content. Reducing dietary CP content from high to low diminished the N output by approximately 20%. The conclusions are that growing-finishing pigs had the capacity for compensatory growth and can therefore be single-phase-fed, and that the current recommendations of CP and Lys could be reduced.

The influence of dietary protein and energy levels on the performance, meat bone ratio and meat chemical composition of SenSi-1 Agrinak chicken

&lt;p class="Default"&gt;&lt;span lang="EN-US"&gt;Sensi-1 Agrinak is a strain of the improved native chickens for meat production in Indonesia. The objective of &lt;/span&gt;&lt;span lang="IN"&gt;this&lt;/span&gt;&lt;span lang="EN-US"&gt; study was to investigate influence of different dietary energy and protein levels on &lt;/span&gt;&lt;span lang="IN"&gt;p&lt;/span&gt;&lt;span lang="EN-US"&gt;erformance, meat bone ratio&lt;/span&gt;&lt;span lang="IN"&gt;,&lt;/span&gt;&lt;span lang="EN-US"&gt; and meat chemical composition of Sensi-1 Agrinak chicken, reared until 10 weeks of age. Two hundred and sixteen of unsexed day old chickens (DOC) of Sensi-1 Agrinak were subjected to six experimental rations differed in dietary crude protein (CP) content,. &lt;/span&gt;&lt;span lang="IN"&gt;Namely:&lt;/span&gt;&lt;span lang="EN-US"&gt; 21;19; and 17 % and dietary metabolizable energy (ME) (2800 and 3000 kcal/kg). Each treatment combination was replicated four times and fed from day old to 10 weeks old. In each treatment combination there were nine unsexed-DOCs. The parameters observed were performance (i.e. live weight, feed intake, viability, FCR), economic index (European Production Efficiency Factor/EPEF), meat bone ratio, and meat chemical composition. &lt;/span&gt;&lt;span lang="IN"&gt;R&lt;/span&gt;&lt;span lang="EN-US"&gt;esult showed that &lt;/span&gt;&lt;span lang="EN-US"&gt;increas&lt;/span&gt;&lt;span lang="IN"&gt;ed&lt;/span&gt;&lt;span lang="EN-US"&gt; of dietary CP level increased live weight and EPEF (p&amp;lt;0.05). Sensi-1 Agrinak chicken had the best FCR (2.59), when fed diet containing 21% CP and 3000 kcal/kg. Increas&lt;/span&gt;&lt;span lang="IN"&gt;ed&lt;/span&gt;&lt;span lang="EN-US"&gt; dietary CP level increased the meat-bone ratio of breast, thighs, and drumsticks. Meanwhile, increas&lt;/span&gt;&lt;span lang="IN"&gt;ed&lt;/span&gt;&lt;span lang="EN-US"&gt; levels of dietary CP and ME did not affect (p&amp;gt;0.05) meat chemical composition. It &lt;/span&gt;&lt;span lang="IN"&gt;is&lt;/span&gt;&lt;span lang="EN-US"&gt; concluded that optimal dietary levels of crude protein and energy for unsexed Sensi-1 Agrinak chicken up to 10 weeks of age were 21% CP and 3000 kcal/kg.&lt;/span&gt;&lt;/p&gt;

Optimal dairy feed input selection under alternative feeds availability and relative prices

Feed formulation is essential in the dairy production chain from economic, nutritional, and environmental perspectives. Optimizing the feed formulation across those three domains – given uncertainty of input prices, input availability, and regional climatic conditions – is a challenge for those in the industry. The diet formulation method that is widely used by trading firms and feed production facilities employs a static linear programming (LP) approach. This approach does not allow for intertemporal feed formulations and switches between dietary feed commodities under feed availability conditions, which result in foregone economic gains for feed producers.The current study develops a multi-period LP feed model that uses historical data to capture ration switch opportunities between available feed resources for dairy cows and demonstrates the potential use of the method in different commodity feed availability situations. We apply 14 diet formulations, each covering 150 months, representing a total of 2100 diets. The diet formulation considers a specific milk production level for a “model cow”, alternative feed formulations available, and volatility in feed prices. The results demonstrate that there is an opportunity for efficiency gains in the dairy industry with respect to feed formulation.Based on dietary feed inclusion and price spreads, barley can be an important dairy feed grain which completely replaces wheat, corn, and sorghum at price spreads of less than 94%, less than 78%, and less than 67%, respectively. Grain-based feed scenarios represent the lowest nutrient variation while multiple meal feeds had the lowest costs. Furthermore, and on average, multiple meal feed scenarios provided 10% higher dietary crude protein contents compared to grain based feed scenarios (i.e. 163 vs 179 g/kg DM formulated feed). Meanwhile, multiple meal feeding cost was 11% lower than that in the grain based feeding scenarios. Additionally, the use of multiple meals reduces alfalfa dietary inclusion by 7% on dry matter basis. Our analysis shows a strong reduction in feed cost associated with dietary crude protein reduction equivalent to 7.6 USD/tonne per 1% reduction in dietary crude protein level.The modeling approach allows for the interaction between feed components over time taking into consideration volatile global feed prices, thereby improving feed availability and feed formulation. Overall, the model provides a decision making tool to improve the use of feed resources in the dairy sector.

The influence of protein restriction during mid- to late gestation on beef offspring growth, carcass characteristic and meat quality

The objective of this study was to determine whether crude protein intake during the last three months of gestation affects growth performance, carcass characteristics and meat quality of steer progeny. At 134 ± 14 d of gestation, 68 multiparous Angus cows were blocked by BW and expected calving date and randomly assigned to diets that contained either low or high dietary crude protein concentrations and were allotted in 12 pens per treatment. After calving, cows were managed together on improved pastures during lactation. After weaning at 219 ± 13 d of age, steers calves were stockered on natural pastures until 687 ± 13 d of age then placed into a feedlot for 83d before slaughter. Maternal dietary protein concentration had no influence on offspring body weight and growth rate during rearing or finishing phases (P > .10). Rib fat thickness of steers was not affected (P = .38) by maternal nutrition treatments, however, LM area was greater in HP steers than LP steers at entrance into the feedlot (P = .01) and end of finishing phase (P = .04). Hot carcass weight was similar between treatments (P = .69), however dressing percentage was increased in HP relative to LP steers (P = .01). Tenderness of Longissimus muscle was increased in HP compared to LP steers after 3 and 14d (P < .001) of aging. No treatment differences in troponin-t degradation (P = .77) and collagen content (P = .58) were observed. Muscle fiber diameter was similar in LP and HP steers (P = .20), suggesting that increase of LM area in HP steers could be due to muscle hyperplasia. These data indicated that level of protein during mid to late gestation does not affect offspring growth but has impacts on carcass composition and meat quality of steer progeny.

Effect of heat load and dietary protein on oxygen pulse and energy cost for locomotion in heifers

The objectives of the present study were to evaluate the effect of heat load, bodyweight and dietary protein on oxygen pulse of heifers, to obtain the energy cost of walking on flat and sloping terrain, and to compare the energy cost of heifers during continuous walking and intermittent walking. In Experiment 1, the correlations of oxygen consumption, heart rate and oxygen pulse (O2P) with bodyweight, black globe temperature and temperature and humidity index were examined. Moreover, the effect of dietary protein on O2P was evaluated. The temperature and humidity index and black globe temperature had a low positive correlation with O2P and oxygen consumption, and a low negative correlation with heart rate. However, weight had no correlation with O2P. There was a linear increase in O2P with a very low adjustment with an increasing dietary crude protein concentration. In Experiment 2, the energy cost of heifers walking continuously at a constant speed in a terrain with 0%, 6% and 12% gradient was measured. The energy expenditure was similar among the terrain gradients. The heifers walking had a 16.6% higher energy expenditure than when they were standing. In Experiment 3, a comparison of the energy cost was made among heifers standing, continuously walking and intermittently walking at a constant speed on flat ground. The energy cost for walking was similar between continuous and intermittent walking. The heat load, bodyweight and dietary protein concentration had a low effect on O2P in dairy heifers. Therefore, measurements over a short time (5–15 min) are a reliable estimator of O2P through the day. Both intermittent and continuous walking can be used to evaluate energy expenditure.

Effects of dietary protein and lipid levels on growth, body composition and nutrient utilization of Channa striata

Very limited information is available on nutrient requirements of Channa striata, particularly during the grow-out stage. A study was carried out to study the requirement and utilization of protein and lipid by Channa striata growing from 31 g to ~ 200 g. Nine experimental diets with graded levels of dietary protein and lipid were formulated using practical ingredients. Increasing dietary crude protein content from 43.4% to 55.6% at 11% dietary lipid content resulted in increases of weight gain, amount of feed consumed, specific growth rate, and thermal-unit growth coefficient. The crude protein requirement of Channa striata was estimated by the saturation kinetics model to be 51.6% dry matter (DM) for growth and 52.1% DM for protein deposition. On the digestible protein basis, the requirement of Channa striata was estimated to be 47.2% DM for growth and 47.8% DM for protein deposition. Increasing lipid content in diets from 7.5% to 23.1% in this study resulted in linear decreases of fish growth and feed intake. Apparently Channa striata cannot tolerate high dietary lipid levels; lipid levels of >19% DM could negatively affect growth performance. It was also revealed that dietary lipids did not have a protein-sparing effect in Channa striata. Results from this study not only contribute to a better understanding of the nutrient requirement and utilization of Channa striata, but also would be helpful for the development of cost-effective sustainable practical feed formulations for this fish species.

Eutrophication risk arising from intensive dairy cattle rearing systems and assessment of the potential effect of mitigation strategies

Nitrogen (N) and phosphorus (P) are fundamental nutrients in dairy cattle nutrition, but the majority of N and P fed to dairy cattle is excreted in urine and faeces, which may cause water eutrophication. The aim of the current study has been to assess the eutrophication risk of dairy production in order to evaluate potential mitigation strategies. A group of 16 dairy farms, which follow an intensive rearing system and are located in the northwest of Italy, was involved in the study. Data pertaining to the general characteristics of the farms, to the diet compositions, feed samples and the livestock productive and reproductive performances as well as information on the management practices were collected to evaluate the N and P feed contents of the diets, the N and P contents of the manure and the apparent N and P utilization efficiency at a herd level and for each category of reared animal (i.e., lactating cows, dry cows, heifers and calves). In order to accurately assess the environmental risk, the N release losses into the atmosphere, prevalently as ammonia, were considered, and the different forms of released N and P were converted into their phosphate equivalent (PO4). On the basis of the characteristics of each farm, some common dietary manipulation mitigation strategies, such as the adoption of precision feeding and the reduction of the protein content of the diet, were proposed to evaluate their potential reduction of the excreted nutrients. The results of the feed analysis showed interesting and notable differences from previously reported N and P contents in the diets of dairy cows. The N balance conducted on these farms showed relatively good fitness of the diet for lactating cows, with only a slight deficit in crude protein supplementation (-2%), while the diets for dry cows were slightly more unbalanced for N (+17%). The P balance calculations revealed a large excess of P in the diets of the farms in this study, especially for heifers (+106%). The highest levels of N- and P-use efficiency were found for cows (20 and 28%, respectively), while the lowest ones were found for young heifers and calves (0–12 months; 7 and 11% N- and P-use efficiency, respectively). It is possible to reduce N and P losses by levelling out this unbalance and in addition, in particular for N, by generally reducing the diet crude protein content by at least 1%. The estimated reduction in PO4 by dietary manipulation was assumed to decrease the environmental eutrophication risk by 17%. On the basis of these results, and considering the number of the dairy cattle reared in northern Italy, it is possible to estimate that the potential reduction in N and P excretion by dietary manipulation could be equivalent to 5693.5 metric T y−1 or 1 metric T km-2 of Utilized Agricultural Area per year of PO4.

Digestion and nitrogen excretion by Holstein-Friesian cows fed grasses with lucerne or lucerne and plantain

Forages and forage mixtures with greater tolerance of dry conditions than perennial ryegrass (Lolium perenne L.) are desirable for dairy farming in New Zealand, and a low urinary nitrogen (N) excretion is desirable to lessen pollution of waterways and ground water, and nitrous oxide emissions. Measurements were undertaken with late-lactation Holstein-Friesian cows (5/treatment) fed tall fescue (Festuca arundinacea Schreb.) with a substantial incursion of weed grasses, as either a sole diet (Grass), or with lucerne (Medicago sativa L.) or lucerne and plantain (Plantago lancelota L.), in metabolism stalls. Approximate ratios (DM basis) of Grass with lucerne (GL) were 55:45, and Grass with lucerne and plantain (GLP) were 55:25:20. Measurements included intakes, production, digestion, rumen function, and urinary excretion, including the circadian patterns of metabolite excretion with a focus on nitrogenous aspects. The DM intakes (kg/day) of cows fed Grass, GL and GLP were 14.9, 12.7 and 15.0 (P = 0.006), and DM digestibility (%) was 58.0, 59.8 and 61.9 (P = 0.006), respectively. Milk yields (kg/day) were Grass, 9.0; GL, 8.7 and GLP, 11.7 (P = 0.003) but composition was not affected by diet. Rumen digesta weight was greatest in cows fed Grass, averaging 23.4% of liveweight after morning feeding. The microbial growth (g/kg organic matter digested) was 16.8 in cows fed Grass and ~24.0 in the other diets. Dietary crude protein concentrations (g/100 g DM) were Grass, 15.4, GL, 20.1 and GLP, 18.3 and urinary N excretion (g/day) was lowest with the Grass diet but urinary N concentration was lowest from cows fed GLP. Daily creatinine excretion was unaffected by diet but there was a 2-fold range in excretion rates within 24 h and values from cows fed fresh forages are lower than published values from cows fed dry diets. Results showed that supplementation of poor quality pasture with lucerne or lucerne with plantain had minor effects on digestibility, and measurements of urinary N suggest a need for caution when predicting urinary N excretion from spot urine sampling in grazing trials.

Short communication: Antimethanogenic effects of 3-nitrooxypropanol depend on supplementation dose, dietary fiber content, and cattle type

3-Nitrooxypropanol (NOP) is a promising methane (CH4) inhibitor. Recent studies have shown major reductions in CH4 emissions from beef and dairy cattle when using NOP but with large variation in response. The objective of this study was to quantitatively evaluate the factors that explain heterogeneity in response to NOP using meta-analytical approaches. Data from 11 experiments and 38 treatment means were used. Factors considered were cattle type (dairy or beef), measurement technique (GreenFeed technique, C-Lock Inc., Rapid City, SD; sulfur hexafluoride tracer technique; and respiration chamber technique), dry matter (DM) intake, body weight, NOP dose, roughage proportion, dietary crude protein content, and dietary neutral detergent fiber (NDF) content. The mean difference (MD) in CH4 production (g/d) and CH4 yield (g/kg of DM intake) was calculated by subtracting the mean of CH4 emission for the control group from that of the NOP-supplemented group. Forest plots of standardized MD indicated variable effect sizes of NOP across studies. Compared with beef cattle, dairy cattle had a much larger feed intake (22.3 ± 4.13 vs. 7.3 ± 0.97 kg of DM/d; mean ± standard deviation) and CH4 production (351 ± 94.1 vs. 124 ± 44.8 g/d). Therefore, in further analyses across dairy and beef cattle studies, MD was expressed as a proportion (%) of observed control mean. The final mixed-effect model for relative MD in CH4 production included cattle type, NOP dose, and NDF content. When adjusted for NOP dose and NDF content, the CH4-mitigating effect of NOP was less in beef cattle (-22.2 ± 3.33%) than in dairy cattle (-39.0 ± 5.40%). An increase of 10 mg/kg of DM in NOP dose from its mean (123 mg/kg of DM) enhanced the NOP effect on CH4 production decline by 2.56 ± 0.550%. However, a greater dietary NDF content impaired the NOP effect on CH4 production by 1.64 ± 0.330% per 10 g/kg DM increase in NDF content from its mean (331 g of NDF/kg of DM). The factors included in the final mixed-effect model for CH4 yield were -17.1 ± 4.23% (beef cattle) and -38.8 ± 5.49% (dairy cattle), -2.48 ± 0.734% per 10 mg/kg DM increase in NOP dose from its mean, and 1.52 ± 0.406% per 10 g/kg DM increase in NDF content from its mean. In conclusion, the present meta-analysis indicates that a greater NOP dose enhances the NOP effect on CH4 emission, whereas an increased dietary fiber content decreases its effect. 3-Nitrooxypropanol has stronger antimethanogenic effects in dairy cattle than in beef cattle.

Low-Protein Diets Decrease Porcine Nitrogen Excretion but with Restrictive Effects on Amino Acid Utilization.

Reducing dietary crude protein (CP) intake effectively decreases nitrogen excretion in growing-finishing pigs but at the expense of poor growth when dietary CP content is reduced by ≥3%. In this study, we investigated the main disadvantages of low-protein diets supplemented with lysine, methionine, threonine, and tryptophan in pigs. First, changes in the nitrogen balance in response to differences in dietary CP content (18%, 15%, and 13.5%) were investigated in barrows (40 kg). Then, barrows (40 kg) surgically fitted with catheters in the mesenteric vein, portal vein, hepatic vein, and carotid artery were used to investigate changes in amino acid (AA) metabolism in the portal-drained viscera and liver in response to differences in dietary CP content. The results showed that low-protein diets reduced fecal and urinary nitrogen excretion ( P < 0.05) meanwhile resulted in significant decreases in nitrogen retention ( P < 0.05). Moreover, a reduction in the dietary CP content from 18% to 13.5% resulted in decreases in the net portal fluxes of NH3, glycine, and alanine as well as in the urea production in the liver ( P < 0.05), whereas their values as a percentage of nitrogen intake did not decline ( P > 0.05). The net portal fluxes of nonessential AA (NEAA) were reduced in the low-protein diet groups ( P < 0.05), while essential AA consumption in the liver increased ( P < 0.05). Thus, low-protein diets result in reductions in both nitrogen excretion and retention, and NEAA deficiency may be a major disadvantage of low-protein diets.

تأثير مستويات البروتين الغذائي في أداء نمو كتاكيت النعام خلال 2-10 أسابيع من العمر

هدفت الدراسة الحالية إلى معرفة تأثير تغذية أفراخ النعام على عليقه ذات تركيزات مختلفة من البروتين (18%-21%) على قياسات كفاءة النمو في أفراخ النعام والتي تشمل: معدل الزيادة اليومية في الجسم الحي, معدل استهلاك الغذاء, معدل التحويل الغذائي ومعدل كفاءة البروتين خلال الفترة من 2 إلى 10 أسابيع من عمر النعام. تم استخدام عشرين طيراً من أفراخ النعام الغير مميزة جنسياً، وتم تقسيمهم إلى مجموعتين, حيث احتوت كل مجموعة على عشرة أفراخ. المجموعة الأولى قدمت لها عليقه تحتوي على 18% بروتين, بينما المجموعة الثانية قدمت لها عليقه تحتوي على 21% بروتيناً. وأشارت نتائج هذه التجربة إلى أن الوزن البدائي والنهائي للجسم الحي, والوزن المكتسب, معدل استهلاك الغذاء وكذلك معدل التحويل الغذائي لم يتغيرا تغيراً معنوياً باختلاف تركيز البروتين في العليقة, بينما أوضحت النتائج أن هناك زيادة معنوية في معدل كفاءة البروتين في المجموعة الأولى مقارنة بالمجموعة الثانية. كما أظهرت نتائج الدراسة الحالية بأن تغذية أفراخ النعام على عليقة ذات تركيزات مختلفة من البروتين لم تؤثر على كفاءة النمو, بينما أوضحت النتائج بأن أفضل معدل لكفاءة البروتين كان نتيجة تناول أفراخ النعام عليقة تحتوي على بروتين أقل.

Milk production of Norwegian Red dairy cows on silages presumed either low or optimal in dietary crude protein content

Dairy cow diets often exceed protein requirements for milk production. At the same time, dietary protein use efficiency for milk production is low leading to excretion of large amounts of nitrogen to the environment. We assessed the effects of feeding two grass/clover silages mainly differing in crude protein (CP) content on milk and component yields, nitrogen and gross feed utilization efficiency with Norwegian Red dairy (NRF) cows. Forty-eight early- to mid-lactation NRF dairy cows were randomly allocated to two dietary treatments (n = 24) after blocking by initial milk yield, stage of lactation, body weight and parity. Cows were fed silages either low in CP (late cut silage, LCPS; 112 g CP per kg dry matter (DM)) or optimal (mixture of 4 different silages, OCPS; 142 g per kg DM) ad libitum for a period of 54 days. These basal diets were augmented with a fixed level of concentrate feed (160 g CP per kg DM). This was estimated using the Nordic Feed Evaluation System (TINE Optfor KU optimization program) assuming OCPS as an available silage. We hypothesized that OCPS would support higher milk yield than LCPS, and the LCPS cows would consume more feed if they were to achieve similar level of milk yield as their OCPS counterparts. Contrary to our hypothesis, milk (23.7 vs. 24.5 kg per day), energy corrected milk (25.2 vs. 25.6 kg per day) yields and milk components were not significantly different between the groups (LCPS vs. OCPS). Furthermore, LCPS cows sufficiently matched DMI from the silage part of the diet to that of the OCPS cows (12.7 vs. 12.4 kg per day). However, OCPS decreased (P < 0.01) nitrogen use efficiency compared to the LCPS (30 vs. 33%). Our results confirm that reduction in dietary CP levels (ca 130 g per kg DM) can be achieved without loss of production, with reduced N excretion to the environment and reduced cost of milk production in moderately yielding cows. This would have a positive contribution to the current efforts being made to base our dairy production on locally available resources with minimal recourse to imported inputs.

Effects of feeding reduced crude protein diets on growth performance, nitrogen excretion, and plasma uric acid concentration of broiler chicks during the starter period

An experiment (2 trials) was conducted to determine the effects of feeding reduced crude protein (CP) diets to Ross × Ross 708 male broilers while maintaining adequate essential amino acid (AA) concentrations on growth performance, nitrogen excretion, and plasma uric acid (UA) concentration during the starter period. In trial 1, 11 dietary treatments were fed from 1 to 18 d of age containing 1.20% digestible Lys. Diet 1 (23.2% CP) was formulated with DL-Met, L-Lys, and L-Thr to contain 1.70 total Gly + Ser to digestible Lys ratio whereas diets 2 (23.4% CP) to 11 were formulated with additional Gly to contain 1.90 total Gly + Ser to digestible Lys ratio. Free AA were added sequentially in the order of limitation (L-Val, L-Ile, L-Arg, L-Trp, L-His, L-Phe, and L-Leu) from diets 3 to 10 to decrease CP content from 22.6 to 18.8%, respectively. In diet 11, L-Gln was added to increase the CP content to 23.4%. Feed conversion of broilers fed diet 2 was lower (P < 0.05) than those consuming diets 6 to 11 from 1 to 17 d of age. Nitrogen excretion (mg/b/d) decreased (P < 0.001) by 14.1% when broilers were fed diet 4 compared with birds fed diet 2 from 15 to 16 d of age. Broilers fed diet 4 had lower (P = 0.011) plasma UA concentration than birds fed diet 2 at 18 d of age. In trial 2, 8 dietary treatments containing 1.25% digestible Lys and 1.70 total Gly + Ser to digestible Lys ratio were fed from 1 to 21 d of age. Diet 1 (24.0% CP) was supplemented with DL-Met, L-Lys, and L-Thr. Free AA (L-Val, Gly, L-Ile, L-Arg, L-Trp, L-His, and L-Phe) were sequentially supplemented in the order of limitation to decrease CP content in diets 2 to 8 from 23.8 to 20.3%. Broilers fed diet 1 had higher (P < 0.05) body weight gain and lower (P < 0.05) feed conversion when compared with diet 7 or 8. Plasma UA concentration of broiler provided diets 4 to 8 was lower (P < 0.05) compared with diet 1 at 21 d of age. Placing a minimum on dietary CP percentage may not be necessary when proper AA ratios are implemented in diet formulation.

Increased dietary protein or free amino acids supply for heat stress pigs: effect on performance and carcass traits.

Heat stress (HS) pigs reduce their voluntary feed intake (VFI) and ingestion of indispensable amino acids (AA). Increasing the dietary crude protein (CP) content may help to correct the reduced AA intake by HS pigs, but it may further increase their body heat load. Increasing the AA intake by adding free AA to the diet does not affect the heat load of HS pigs. Two 21-d experiments were conducted. In Exp. 1, 30 pigs (31.1 ± 1.2 kg initial body weight) were used to determine the performance depression because of HS. Treatments were: thermo neutral pigs fed a 22% CP control diet (TN-C); HS pigs fed the control diet (HS-C); HS pigs fed a 14% CP, AA supplemented diet (HS-AA). HS pigs had lower ADG and Lys utilization efficiency, and consumed 20 and 25% less Lys and Thr, respectively, than the TN-C pigs (P < 0.05). In Exp. 2 (comparative slaughter), 25 pigs (33.6 ± 0.65 kg initial body weight) were used to evaluate the effect of extra dietary AA either as protein-bound or free AA on the performance and carcass traits of HS pigs. Treatments were: control wheat-SBM-free Lys, Thr and Met diet (CON); diet with 30% more CP than CON (HSxP); diet added with free AA to contain at least 25% more of each AA than the recommended level (HSxAA). Ambient temperature (AT) ranged from 27.7 to 37.7°C, and body temperature (39.9 to 41.2°C) followed a similar daily pattern as the AT did. There was no dietary treatment effect on daily feed and NE intake (P > 0.10), but the Lys, Thr, and Met intake was higher in pigs fed the HSxP or HSxAA diets than in pigs fed the CON diet (P < 0.05). The daily weight gain (ADG) was not affected (P > 0.10) but G:F tended to be higher and the Lys utilization efficiency (ADG, g/g Lys intake) tended to be lower in HSxP pigs than in CON pigs (P < 0.10). The HSxAA pigs had higher ADG (P < 0.05), and tended to have higher weight of hot carcass and leg muscle, and the weight gain of hot carcass and leg muscle than the CON pigs (P < 0.10). The weight and daily weight gain of loin muscle was higher in the HSxAA than in the HSxP pigs (P < 0.05). Kidney weight and serum urea in HSxP pigs were higher than in CON and HSxAA pigs, but spleen weight was higher in HSxAA pigs than in CON and HSxP pigs (P < 0.05). These results confirm that HS reduces the VFI, and show that increased levels of AA either as free or protein-bound do not additionally reduce the VFI of HS pigs. These also show that extra free AA supply rather than protein-bound AA better ameliorate the reduced growth performance of HS pigs.