Dietary Crude Protein Content Research Articles

Influence of the protein status of piglets on their ability to select and prefer protein sources

Pigs may have retained the capacity to choose feeds based on their nutritional requirements, even after decades in which they are not allowed to select their diet composition due to the common feeding systems of the intensive pig industry. We used 480 early-weaned piglets in two experiments to assess their ability to select and prefer protein-related sources, depending on their protein status. Piglets were fed after weaning with two isoenergetic diets formulated to contain an optimal or sub-optimal crude-protein (CP) content, a high-protein (HP, 204g CP/kg as-fed) or a low-protein diet (LP, 142g CP/kg), respectively. In Experiment 1, the preference of piglets was assessed by using a choice test between protein (porcine digestible peptides [PDP] 40g/L) and carbohydrate (sucrose 40g/L) water-based solutions for a period of 3min. Piglets showed higher intake and preference for the sucrose 40g/L than for the PDP 40g/L solution, independently of the dietary CP content (9.8mL/kg body weight [BW] vs. 3.7mL/kg BW and 10.4mL/kg BW vs. 4.3mL/kg BW in HP and LP pigs, respectively). In Experiment 2, piglets were given eight training sessions in which two equally preferred flavors were mixed with protein (porcine animal plasma 60g/L, CSp) or carbohydrate (maltodextrin 60g/L, CSc) solutions. In the subsequent choice test, piglets fed the HP diet showed a tendency to a higher intake of CSc than of CSp (6.5mL/kg BW vs. 5.4mL/kg BW). On the other hand, piglets fed the LP diet showed a higher intake and preference for CSp than for CSc (15.5mL/kg BW vs. 10.2mL/kg BW), differences being higher for medium and low BW piglets than for heavy ones. The results show that piglets are unable to express a specific appetite for protein to correct previous underfeeding with it; however, they may show an appropriate dietary selection pattern in order to overcome protein deficiency through associative learning.

Dietary Protein Requirement of Juvenile Cachara Catfish, Pseudoplatystoma reticulatum

AbstractCachara, Pseudoplatystoma reticulatum, is a high commercial value carnivorous catfish in Brazil, but whose dietary protein requirement is still unknown. Aiming to determine this requirement, groups of 15 juveniles (16.08 ± 1.13 g) were fed isoenergetic diets (4600 kcal/kg gross energy) with increasing levels of crude protein (30, 35, 40, 45, 50, and 55%). After 60 d, regression analysis revealed a quadratic effect (P < 0.05) of increasing dietary crude protein concentration on growth variables. The highest weight gain and specific growth rate as well as the best feed conversion were shown by fish fed the 50% crude‐protein diet. Similarly, protease activities were significantly higher (P < 0.05) in fish fed 50% crude protein. However, the highest protein retention was observed in fish fed the 45% crude‐protein diet. Protein and dry matter digestibilities did not differ (P > 0.05) for diets containing 40, 45, or 50% crude protein. Therefore, based on weight gain and at a dietary energy concentration of 4600 kcal/kg, the estimated protein requirement for juvenile cachara between 16 and 85 g is 49.25% crude protein. This is equivalent to 44.79% digestible protein and a gross energy to digestible protein ratio of 10.27 kcal/g.

Evaluation of equations predicting the net portal appearance of amino acid nitrogen in ruminants

A better assessment of digestible protein and AA flows is required to improve the predictions of animal performance in ruminants (e.g., growth and yields of milk and milk protein). In that respect, 2 recent meta-analyses were conducted in our laboratory to establish the relationships between net portal appearance of AA nitrogen (NPA-AAN) and dietary characteristics either from the National Research Council (Washington, DC) or Institut National de la Recherche Agronomique (INRA; St Genès Champanelle, France). Three prediction equations were selected from these meta-analyses: one equation based only on N intake (NI) and 2 equations based on NI, the intake of neutral detergent fiber, plus the dietary concentration of either total digestible nutrients or digestible organic matter. In the current meta-analysis, 2 new equations were developed to predict NPA-AAN from the estimated supply of metabolizable protein (MP) and the protein truly digestible in the intestine (PDI). The reliability of these 5 equations to predict NPA-AAN was evaluated using an independent database. On average, NPA-AAN predictions based on the supply of MP or PDI had the highest coefficient of determination and the lowest root of mean square prediction error and mean and regression biases compared with predictions based on dietary characteristics, suggesting better reliability with the former. No major difference was detected between NPA-AAN predictions based on parameters from the National Research Council or INRA, except that predictions based on MP had the lowest mean and regression biases. In each equation, mean of residual NPA-AAN (observed NPA-AAN minus predicted values) was lowest and negative for sheep compared with dairy cows, suggesting that NPA-AAN were overpredicted in sheep. Many continuous variables biased NPA-AAN predictions based on NI only, but none of the tested variables biased the predictions based on the supply of MP or PDI, corroborating the better reliability for the prediction equations based on the supply of digestible protein. Of the tested continuous variables, only the dietary concentration of crude protein (CP) biased NPA-AAN predictions based on NI plus dietary characteristics. The NPA-AAN responses to dietary CP concentration were overpredicted as dietary CP concentration increased and underpredicted as CP decreased, suggesting that ruminants were more efficient at converting ingested N into digestible protein when fed low-CP diets compared with high-CP diets.

Growth performance of heavy pigs fed restrictively diets with decreasing crude protein and indispensable amino acids content

This study aimed to investigate the effect of decreasing dietary crude protein (CP) and indispensable amino acid (AA) content, relative to conventional diets, on growth performance of heavy pigs for dry cured ham production. Four dietary treatments (conventional: CONV, medium-high protein, medium-low protein, and low protein: LP) were formulated by replacing soybean meal with wheat grain to contain 146 to 117 and 133 to 108g CP/kg in early (90 to 130kg BW) and late finishing (130 to 165kg BW) periods, respectively. Within period, diets contained the same amounts of indispensable AA per unit of CP, and the standardized ileal digestible (SID) Lys content was 42.2 and 35.5g/kg of CP in early and late finishing periods, respectively. A total of 240 crossbred pigs, grouped in 3 batches of 80 pigs each, were assigned to one of 4 dietary treatments according to BW and sex (10 pigs per pen, gilts and barrows, and 2 pens per treatment in each batch). Pigs were fed restrictively using a single-space electronic feeder, and feed allowance increased from 2.4 at the start (92±10kg BW) to 3.2kg/d at the end of the trial (167±10kg BW), irrespective of sex. Initial and final BW and backfat depth (P2) measures were used to estimate body composition, and lipid and protein retention (Lr and Pr, respectively). These estimates, along with feed intake data, were used to study the partitioning of ME and SID Lys among body functions. Nitrogen excretion (NEx) was estimated as actual N intake – N retention, and N retention was computed as Pr/6.25. Final BW, average daily gain and final P2 backfat averaged 167kg, 0.665kg/d, and 18mm, respectively. Diet had no effect on these traits, as well as on gain to feed ratio (0.253), Lr (265g/d), Pr (95g/d), and the ME available for maintenance (0.845MJ/kg BW0.60). From CONV to LP the SID Lys intake decreased from 137 to 122g/kg Pr, and NEx decreased by 22%. In this production system, a reduction of dietary CP and indispensable AA content is advisable, as no negative impact on growth performance was observed compared to CONV. A reduced inclusion of soybean meal with a minimal supplementation of AA reduces feed costs and NEx. This would increase the number of pigs raised per unit of land where a maximum N load/ha is constrained by law.

Protein Requirements for Laying Indigenous Guinea Fowls (Numida Meleagris) in the Humid Tropical Zone of Ghana

This study was undertaken to assess the dietary crude protein (CP) concentrations required by growing indigenous guinea fowls (Numida meleagris) for optimum growth performance. One hundred and eighty (180) nine-week old pearl guinea fowl growers were randomly assigned to experimental diets with 160, 180, 200 and 220 g/kg CP, from 9 to 27 weeks of age for the growing phase in a complete randomized design (CRD). Rations used in the experiment were isocaloric, having ME of 12.30 MJ/ kg. Each dietary treatment was replicated 3 times, a pre-weighed amount of feed was given and water was provided ad libitum. Feed consumption was measured daily and body weight measured weekly. Mortality was recorded as and when it occurred. Other parameters measured included haematological and biochemical analysis, carcass parameters, age and weight at first lay and weight of first egg. Results show that diets containing 160 g/kg crude protein for growing guinea fowls is ideal for optimum growth performance and production.

Effects of dietary protein concentration on ammonia volatilization, nitrate leaching, and plant nitrogen uptake from dairy manure applied to lysimeters.

This lysimeter experiment was designed to investigate the effects of dietary crude protein (CP) concentration on nitrate-N (NO-N) and ammonia (NH) losses from dairy manure applied to soil and manure N used for plant growth. Lactating dairy cows were fed diets with 16.7% CP (HighCP) or 14.8% CP (LowCP) content. Feces and urine were labeled with N by ruminal pulse-doses of NHCl. Unlabeled and N-labeled feces and urine were used to produce manure for a study with 21 lysimeters in a greenhouse. Manure application rate was 277 kg N ha. Ammonia emissions were measured at 3, 8, 23, 28, 54, and 100 h after manure application. Manure was incorporated into the soil, and a leaching event was simulated. Spring barley was planted (387 plants per m) 7 d after the leaching event and harvested at senescence. Ammonia emission rates and the contribution of urinary N to NO-N were on average about 100% greater for HighCP vs. LowCP manures. With both LowCP and HighCP manures, a greater proportion of urinary vs. fecal N was recovered in leachate NO-N. There was no difference in whole-crop barley N yields between LowCP and HighCP manures, but barley kernel N yield tended to be greater ( = 0.09) for lysimeters treated with HighCP manures. Using a unique labeling approach, this lysimeter experiment demonstrated that when applied at equal soil N application rates, manure from cows fed the HighCP diet resulted in markedly greater NH emissions and urinary N losses with leachate NO-N than manure from cows fed the LowCP diet.

The effects of dietary protein levels on the population growth, performance, and physiology of honey bee workers during early spring.

This study was conducted to investigate the effects of dietary protein levels on honey bee colonies, specifically the population growth, physiology, and longevity of honey bee workers during early spring. Diets containing four different levels of crude protein (25.0, 29.5, 34.0, or 38.5%) and pure pollen (control) were evaluated. Twenty-five colonies of honey bees with sister queens were used in the study. We compared the effects of the different bee diets by measuring population growth, emergent worker weight, midgut proteolytic enzyme activity, hypopharyngeal gland development, and survival. After 48 d, the cumulative number of workers produced by the colonies ranged from 22,420 to 29,519, providing a significant fit to a quadratic equation that predicts the maximum population growth when the diet contains 31.7% crude protein. Significantly greater emergent worker weight, midgut proteolytic enzyme activity, hypopharyngeal gland acini, and survival were observed in the colonies that were fed diets containing 34.0% crude protein compared with the other crude protein levels. Although higher emergent worker weight and survival were observed in the colonies that were fed the control diet, there were no significant differences between the control colonies and the colonies that were fed 34.0% crude protein. Based on these results, we concluded that a dietary crude protein content of 29.5–34.0% is recommended to maximize the reproduction rate of honey bee colonies in early spring.

사료의 조단백질 및 아미노산 함량이 토종오리의 성장과 도체 특성에 미치는 영향

본 실험은 조단백질과 아미노산(Lysine/TSAA) 수준이 토종오리의 생산성 및 도체 특성에 미치는 영향을 연구하기 위해 수행되었다. 육성 전기는 토종오리 450수를 6개 처리에 공시하여 사용하였으며, 육성 후기는 육성 전기를 거친 토종오리 중 360수를 6개 처리에 공시하여 사용하였다. 육성 전기의 실험 사료는 조단백질 23 및 20% 아미노산(Lysine/TSAA)은 각각 1.31/1.09, 1.21/1.00 및 1.11/0.91와 1.11/0.91, 1.02/0.83 및 0.92/0.75였으며, 육성 후기에는 조단백질 19 및 17%, 아미노산(Lysine/TSAA)은 각각 1.00/0.79, 0.94/0.75 및 0.88/0.71와 0.88/0.71, 0.82/0.67 및 0.76/0.63로 처리하여 사용하였다. 육성 전기 실험 결과는 조단백질 수준이 증가함에 따라 생체중과 일당 증체량이 유의적으로 개선되었지만(P<0.05), 아미노산(Lysine/TSAA)과 조단백질 <TEX>${\times}$</TEX> 아미노산(Lysine/TSAA) interaction에 유의차는 나타나지 않았으며, 균일도는 조단백질, 아미노산(Lysine/TSAA) 및 조단백질 <TEX>${\times}$</TEX> 아미노산(Lysine/TSAA) interaction 모두에서 유의차가 나타나지 않았다. 육성 후기 실험 결과는 성장성적, 도체율 및 상대적 중량 모두에서 조단백질, 아미노산(Lysine/TSAA) 및 조단백질 <TEX>${\times}$</TEX> 아미노산(Lysine/TSAA) interaction간 유의차가 나타나지 않았으며, 토종오리 고기의 화학 및 물리적 특성인 육색, pH, 전단력가 및 가열 감량에서도 조단백질, 아미노산(Lysine/TSAA) 및 조단백질 <TEX>${\times}$</TEX> 아미노산(Lysine/TSAA interaction)간 유의차가 나타나지 않았다. 본 실험 결과, 토종오리는 육용종 오리와 달리 육성 후기의 경우 낮은 성장률으로 인하여 상대적으로 낮은 조단백질과 아미노산 수준이 필요할 것으로 사료된다. This study was undertaken to assess dietary crude protein (CP) and amino acid (AA) concentrations for growth performance and carcass characteristics in Korean native ducks. In a <TEX>$2{\times}3$</TEX> factorial arrangement, 1-d-old Korean native male ducks were allotted to 6 dietary treatments in a completely randomized design. Experimental diets contained 23 or 21% CP with 1.31/1.09, 1.21/1.00, 1.11/0.91 and 1.11/0.91, 1.02/0.83, 0.92/0.75 AA (Lysine/Total sulfur amino acid, Lysine/TSAA), respectively, from 0 to 3 wk of age. From 4 to 8 wk of age, experimental diets had 19 or 17% of diet; each contained 1.00/0.79, 0.94/0.75, 0.88/0.71 and 0.88/0.71, 0.82/0.67, 0.76/0.63 AA (Lysine/TSAA), respectively. Each dietary treatment has 6 replicates and feed and water were provided ad libitum. Body weight (BW), feed intake and uniformity were measured at 3 wk and 8 wk and carcass characteristics were evaluated at 8 wk of age. As CP increased from 21 to 23%, the BW and BW gain significantly increased (P<0.05) during 0 to 3 wk of age. From 4 to 8 wk of age, BW, feed intake, BW gain, feed conversion rations (FCR) and uniformity were not different (P>0.05) between treatments. Carcass yield and relative weights of liver, spleen, right breast and leg per 100 of BW were not different (P>0.05) between treatments. The meat color, shear force value, cooking loss and pH were not affected by dietary treatments (P<0.05). Korean native ducks require relatively low levels of dietary CP and AA for late growth and carcass yield due to low daily weight gain. This suggests the possible differences in CP and AA needs between Korean native ducks and commercial breeds from foreign breeding companies, especially late growth stage.

Urea-N recycling in lactating dairy cows fed diets with 2 different levels of dietary crude protein and starch with or without monensin

Rumensin (monensin; Elanco Animal Health, Greenfield, IN) has been shown to reduce ammonia production and microbial populations in vitro; thus, it would be assumed to reduce ruminal ammonia production and subsequent urea production and consequently affect urea recycling. The objective of this experiment was to determine the effects of 2 levels of dietary crude protein (CP) and 2 levels of starch, with and without Rumensin on urea-N recycling in lactating dairy cattle. Twelve lactating Holstein dairy cows (107±21d in milk, 647kg ± 37kg of body weight) were fed diets characterized as having high (16.7%) or low (15.3%) CP with or without Rumensin, while dietary starch levels (23 vs. 29%) were varied between 2 feeding periods with at least 7d of adaptation between measurements. Cows assigned to high or low protein and to Rumensin or no Rumensin remained on those treatments to avoid carryover effects. The diets consisted of approximately 40% corn silage, 20% alfalfa hay, and 40% concentrate mix specific to the treatment diets, with 0.5kg of wheat straw added to the high starch diets to enhance effective fiber intake. The diets were formulated using Cornell Net Carbohydrate and Protein System (version 6.1), and the low-protein diets were formulated to be deficient for rumen ammonia to create conditions that should enhance the demand for urea recycling. The high-protein diets were formulated to be positive for both rumen ammonia and metabolizable protein. Rumen fluid, urine, feces, and milk samples were collected before and after a 72-h continuous jugular infusion of 15N15N-urea. Total urine and feces were collected during the urea infusions for N balance measurements. Milk yield and dry matter intake were improved in cows fed the higher level of dietary CP and by Rumensin. Ruminal ammonia and milk and plasma urea nitrogen concentrations corresponded to dietary CP concentration. As has been shown in vitro, Rumensin reduced rumen ammonia concentration by approximately 23% but did not affect urea entry rate or gastrointestinal entry rate. Urea entry rate averaged approximately 57% of total N intake for cattle with and without Rumensin, and gastrointestinal rate was similar at 43 and 42% of N intake for cattle fed and not fed Rumensin, respectively. The cattle fed the high-protein diet had a 25% increase in urea entry rate and no effect of starch level was observed for any recycling parameters. Contrary to our hypothesis, Rumensin did not alter urea production and recycling.

Níveis de proteína na dieta de novilhas da raça Pantaneira: desempenho e digestibilidade aparente

The objective of this experiment was to verify the influence of increasing levels of dietary protein on performance, apparent digestibility and plasma and urinary urea in Pantaneira breed. The data were obtained from 15 heifers, 18 months old and 146 kg initial body weight, fed diets containing 11, 13, 15 and 17 % of crude protein (CP). The animals were confined for 114 days. At intervals of 28 days they were weighed and blood samples and spot samples of feces from the rectum and of urine were taken. The increase in dietary CP content did not influenced dry matter (DM) intake and average daily weight gain (ADG), but improved nutrient digestibility, increased blood nitrogen levels and increased excretion of urinary urea. A mean intake of 5.13 kg DM/animal/day and an ADG of 570 g were observed. Apparent digestibility values of 40.9, 59.6, 39.2, 41.3 and 34,0 % for DM, CP, total carbohydrate, neutral detergent fiber and acid detergent fiber, respectively, were found. Plasma urea concentration was 49.6 mg/dL; and an urinary urea loss of 110,0 g/animal/day was observed.

Rumen fermentation and microbial yield of high- or low-protein diets containing ground soybean seeds or homemade rapeseed expellers evaluated with RUSITEC

Guadagnin, M., Tagliapietra, F., Cattani, M., Schiavon, S., Worgan, H. J., Belanche, A., Newbold, C. J. and Bailoni, L. 2013. Rumen fermentation and microbial yield of high- or low-protein diets containing ground soybean seeds or homemade rapeseed expellers evaluated with RUSITEC. Can. J. Anim. Sci. 93: 363–371. This experiment aimed to compare diets containing two crude protein (CP) concentrations [147 or 109 g kg−1in dry matter (DM)] and two protein sources containing ground soybean seed (GSS) or rapeseed expeller (RSE). Diets were compared in terms of digestibility, volatile fatty acids (VFA) and ammonia concentrations, and N flows, using rumen simulation fermenters (RUSITEC). Home−made RSE (CP=287 g kg−1dry matter and ether extract=199 g kg−1DM) was produced using equipment adopted by small farms. Reduction of dietary CP content did not affect digestibility, except for a reduction of N apparent digestibility (P&lt;0.01), but increased efficiency of N utilization (P=0.001) without affecting microbial N production (P=0.82). Total VFA concentration was not (P=0.56) influenced by CP content. Compared with GSS, RSE exhibited a greater neutral detergent fibre digestibility (P&lt;0.01), it did not influence total volatile fatty acids (VFA; P=0.10) but decreased the proportions of acetate and propionate on total VFA (P&lt;0.001) and increased those of butyrate and branched-chain VFA (P&lt;0.001). Microbial efficiency was comparable for GSS and RSE. Results suggest that reduction of dietary CP concentration in DM did not impair in vitro digestibility and microbial growth. The protein mixture containing homemade RSE showed in vitro fermentative properties and microbial growth comparable with those of GSS.

Estimation of Ammonia Emissions from Beef Cattle Feedyards Using the Process-Based Model Manure-DNDC

<abstract><title><italic>Abstract.</italic></title> Ammonia (NH₃) emissions from beef cattle feedyards result in loss of agronomically important nitrogen (N) and can have negative environmental consequences. Both empirical and process-based models have been developed to estimate NH₃ emissions from various livestock production systems; however, little work has been conducted to assess their accuracy for large, open-lot feedyards. To validate Manure-DNDC, a process-based biogeochemical model, Manure-DNDC-simulated daily NH₃ fluxes were compared to emission data collected from two commercial feedyards, feedyard A and feedyard E, in the Texas High Plains from 2007 to 2009. Model predictions were in good agreement with observations from both feedyards (p < 0.001) and had high sensitivity to variations in air temperature and dietary crude protein (CP) concentration. Predicted mean daily NH₃ flux densities for the two feedyards had 71% to 78% agreement with observed values. In addition, Manure-DNDC estimates of annual feedyard emissions were within 3% to 15% of observations for the two feedyards, whereas a constant emission factor currently in use by the USEPA underestimated feedyard emissions by as much as 79%. The results from this study indicate that Manure-DNDC can be used to quantify average feedyard NH₃ emissions, assist with NH₃ emissions reporting, provide accurate information for legislators and policy makers, investigate methods to mitigate NH₃ loss, and help evaluate the effects of specific management practices on farm nutrient balances.

Interaction between dietary content of protein and sodium chloride on milk urea concentration, urinary urea excretion, renal recycling of urea, and urea transfer to the gastrointestinal tract in dairy cows

Dietary protein and salt affect the concentration of milk urea nitrogen (MUN; mg of N/dL) and the relationship between MUN and excretion of urea nitrogen in urine (UUN; g of N/d) of dairy cattle. The aim of the present study was to examine the effects of dietary protein and sodium chloride (NaCl) intake separately, and their interaction, on MUN and UUN, on the relationship between UUN and MUN, on renal recycling of urea, and on urea transfer to the gastrointestinal tract. Twelve second-parity cows (body weight of 645±37kg, 146±29d in milk, and a milk production of 34.0±3.28kg/d), of which 8 were previously fitted with a rumen cannula, were fitted with catheters in the urine bladder and jugular vein. The experiment had a split-plot arrangement with dietary crude protein (CP) content as the main plot factor [116 and 154g of CP/kg of dry matter (DM)] and dietary NaCl content as the subplot factor (3.1 and 13.5g of Na/kg of DM). Cows were fed at 95% of the average ad libitum feed intake of cows receiving the low protein diets. Average MUN and UUN were, respectively, 3.90mg of N/dL and 45g of N/d higher for the high protein diets compared with the low protein diets. Compared with the low NaCl diets, MUN was, on average, 1.74mg of N/dL lower for the high NaCl diets, whereas UUN was unaffected. We found no interaction between dietary content of protein and NaCl on performance characteristics or on MUN, UUN, urine production, and renal clearance characteristics. The creatinine clearance rate was not affected by dietary content of protein and NaCl. Urea transfer to the gastrointestinal tract, expressed as a fraction of plasma urea entry rate, was negatively related to dietary protein, whereas it was not affected by dietary NaCl content. We found no interaction between dietary protein and NaCl content on plasma urea entry rate and gastrointestinal urea entry rate or their ratio. The relationship between MUN and UUN was significantly affected by the class variable dietary NaCl content: UUN=−17.7±7.24 + 10.09±1.016 × MUN + 2.26±0.729 × MUN (for high NaCl); R2=0.85. Removal of the MUN × NaCl interaction term lowered the coefficient of determination from 0.85 to 0.77. In conclusion, dietary protein content is positively related to MUN and UUN, whereas dietary NaCl content is negatively correlated to MUN but NaCl content is not related to UUN. We found no interaction between dietary protein and NaCl content on performance, MUN, UUN, or renal urea recycling, nor on plasma urea entry rate and urea transfer to the gastrointestinal tract. For a proper interpretation of the relationship between MUN and UUN, the effect of dietary NaCl should be taken into account, but we found no evidence that the effect of dietary NaCl on MUN is dependent on dietary protein content.

EFFECTS OF DIETARY PROTEIN AND LIPID LEVELS ON GROWTH, FEED UTILIZATION AND BODY COMPOSITION OF CYPRINUS LONGIPECTORALIS

Cyprinus longipectoralis,also known as the spring carp,is a native fish with high economic and ecological value in the Erhai Lake,Yunnan Province,China.Since the 1970’,this fish species seldom appeared in the catch of Erhai Lake,because of overfishing and some other ecological reasons.In recent years,spring carps were recruited through artificial breeding and stock enhancement.However,during the artificial breeding process,farmers could not find a suitable commercial feed because little was known about the nutrient requirements of this species.As two main dietary nutrients,protein and lipid play a key role in fish growth and development.Therefore,this study was designed to investigate the effects of dietary protein and lipid levels on the growth,feed utilization and body composition of juvenile spring carps and the dietary protein and lipid requirements of this fish with initial body weight of 0.55 g,based on the broken-line method.The experimental diets were formulated based on casein,wheat middling,fish oil,corn oil and corn starch.This study adopted a factorial design of 3(protein level) × 3(lipid level) and the nine isocarlorie(17.8 kJ/g) diets contained the protein concentrations of 33%,39% or 45% and the lipid concentrations of 5%,8% or 11%,respectively.One of the nine experimental diets was fed to 30 fish in each tank(67 cm × 46 cm × 50 cm,with a water volume of 130 L) in triplicate for 56 days.During the experiment,the fish were fed by hand to satiation twice daily in an indoor flow system at(28±2)℃,and unconsumed feeds were siphoned 1h after feeding,dried and weighed.The results showed that there were no significant effects of dietary protein and lipid levels on growth,feed utilization and body composition except whole body moisture content(P0.05).Feeding rate decreased significantly while feed efficiency,energy retention efficiency,whole body protein and moisture content significantly increased with the increasing crude protein concentrations(P0.05).Specific growth rate,protein efficiency ratio,protein retention efficiency,and whole body ash content were not significantly affected by dietary crude protein concentrations(P0.05).Whole body lipid content significantly increased while specific growth rate,protein retention efficiency and whole body protein content significantly decreased with the increasing crude lipid concentrations(P0.05).However,feeding rate,feed efficiency,energy retention efficiency and whole body ash content were not significantly affected by dietary crude lipid levels(P0.05).Broken-line analysis based on specific growth rate showed that the optimum dietary protein/lipid ratio of juvenile spring carps was 7.30.We concluded that 33%—34% dietary crude protein level and 4%—5% lipid level were optimal for juvenile Cyprinus longipectoralis.

Diet factors and subclinical laminitis score in lactating cows of smallholder dairy farms in Thailand

The objective of this study was to evaluate the importance of dietary crude protein (CP) content, dietary neutral detergent fiber (NDF) content and feeding regime as well as other factors related to management and demographics on the occurrence of (subclinical) laminitis under practical Thai feeding conditions. Hemorrhage of the white line and the sole, sole ulcer and white-line fissure of all four claws of milking cows (n=119) on 25 farms (selected based on the occurrence of lameness) were macroscopically assessed to calculate the prevalence of subclinical laminitis (SCL) on each farm. Data were collected on farm characteristics, feed and feeding management, floor type and hoof care. Dry matter intake was assessed on each farm and feed ingredients collected and analyzed for dry matter (DM), CP and NDF. No significant differences were found for farm characteristics such as herd size, number of milking cows, parity and body condition scoring between farms with a low (<25%) or a high prevalence (>25%) of SCL. Percentages of DM and CP content of the rations did not differ, whereas mean NDF content in the ration was significantly higher in the low compared to the high prevalence farms. Multiple regression analysis of the data showed that a ration low in NDF content and/or in combination with the separate feeding of roughage and concentrate was associated with a high SCL prevalence. The results suggest that mixing concentrate with a substantial part of the roughage is an important strategy to prevent SCL in smallholder dairy farms under Thai feeding conditions. In addition, the dietary NDF content but not the dietary CP level is associated with SCL prevalence in dairy cows under Thai feeding conditions.

Prediction of urinary nitrogen and urinary urea nitrogen excretion by lactating dairy cattle in northwestern Europe and North America: A meta-analysis

A meta-analysis was conducted on the effect of dietary and animal factors on the excretion of total urinary nitrogen (UN) and urinary urea nitrogen (UUN) in lactating dairy cattle in North America (NA) and northwestern Europe (EU). Mean treatment data were used from 47 trials carried out in NA and EU. Mixed model analysis was used with experiment included as a random effect and all other factors, consisting of dietary and animal characteristics, included as fixed effects. Fixed factors were nested within continent (EU or NA). A distinction was made between urinary excretions based on either urine spot samples or calculated assuming a zero N balance, and excretions that were determined by total collection of urine only. Moreover, with the subset of data based on total collection of urine, a new data set was created by calculating urinary N excretion assuming a zero N balance. Comparison with the original subset of data allowed for examining the effect of such an assumption on the relationship established between milk urea N (MUN) concentration and UN. Of all single dietary and animal factors evaluated to predict N excretion in urine, MUN and dietary crude protein (CP) concentration were by far the best predictors. Urinary N excretion was best predicted by the combination of MUN, CP, and dry matter intake, whereas UUN was best predicted by the combination of MUN and CP. All other factors did not improve or only marginally improved the prediction of UN or UUN. The relationship between UN and MUN differed between NA and EU, with higher estimated regression coefficients for MUN for the NA data set. Precision of UN and UUN prediction improved substantially when only UN or UUN data based on total collection of urine were used. The relationship between UN and MUN for the NA data set, but not for the EU data set, was substantially altered when UN was calculated assuming a zero N balance instead of being based on the total collection of urine. According to results of the present meta-analysis, UN and UUN are best predicted by the combination of MUN and CP and that, in regard to precision and accuracy, prediction equations for UN and UUN should be derived from the total collection of urine.

Effect of water hyacinth (eichhornia crassipes) silage on intake and nutrient digestibility in cattle fed rice straw and cottonseed cake.

Four crossbred Sindhi heifers with an average body weight (BW) of 135 kg and a mean age of 17 months were used to investigate the effect of feeding different combinations of rice straw and ensiled water hyacinth (EWH) supplemented with a source of protein in the form of cottonseed cake (CSC) on intake and digestibility. Four treatments consisting of graded levels of EWH were arranged in a 4×4 Latin square. The levels of EWH were set at: 0 (EWH0), 15 (EWH15), 30 (EWH30), and 45% (EWH45) of an expected total dietary dry matter (DM) intake of 30 g total DM per kg BW per day. Rice straw was offered ad libitum, while CSC was given at a fixed level of 5 g DM/kg body weight (BW). Voluntary intake and digestibility were measured consecutively in the 4 experimental periods which each lasted 28 days. The crude protein (CP) content of EWH, rice straw and CSC were 174, 53 and 370 g/kg DM, respectively. Rice straw had the highest neutral detergent fibre (NDFom) content (666 g/kg DM), followed by EWH (503 g/kg DM) and the lowest content was 418 g/kg DM in the CSC. The actual EWH contents in the consumed diets were 0, 17, 32 and 52% for EWH0, EWH15, EWH30 and EWH45, respectively. Rice straw intake decreased with level of EWH offered from 3049 for EWH0 to 1014 g/day for EWH45. Crude protein intake was 16, 25 and 33% higher (p<0.001) in EWH15, EWH30 and EWH45 treatments, respectively, as compared to EWH0. Digestibility of organic matter (OM), CP, NDFom and acid detergent fibre (ADFom) increased with increasing level of EWH offered. The highest OM digestibility (72.2%) was found for treatment EWH45 and the lowest (47.4%) for treatment EWH0. In spite of similar dietary CP contents, CP digestibility increased by 21 (EWH15), 31 (EWH30) and 40% (EWH45) with increasing level of EWH in comparison with treatment EWH0. It is concluded that increasing level of EWH in cattle diets considerably improved CP intake and digestibility of nutrients.

Response of the Iberian sow to protein supply and feeding level during late gestation

One hundred and twenty purebred Iberian (IB) sows in their second or third parity were used in two consecutive trials to determine the effects of dietary crude protein (CP) concentration and feeding level (FL) during late gestation on sow and litter performance. The sows were kept in groups in open-air, fenced spaces and randomly assigned from day (d) 70 of gestation to one of four experimental treatments in a 2×2 factorial arrangement with 2 CP levels (120 and 101g CP/kg diet) and 2 FL (2.33 and 2.67kg/d; metabolizable energy (ME) content, 12.50MJ/kg diet). Nearing farrowing the sows were housed individually and fed a lactation diet (148g CP/kg; 4.5kg/d) for a 35-d lactation period. Piglets had no access to any feed. Body weight (BW) gain from d 70 of gestation to farrowing increased with FL (23.8±0.88 vs. 27.3±0.86kg; P<0.01, in second-parity sows; 18.2±1.14 vs. 25.0±1.23; P<0.001, in third-parity sows), but was not affected by dietary CP content. Average BW gains were 25.6±0.59 and 21.6±0.83kg in second- and third-parity sows, respectively. Body weight loss during lactation was not affected by FL, and in second-parity sows it tended to increase with the lowest CP diet (P=0.071). The CP×FL interactions were never significant (P>0.05). The dietary factors did not affect plasma metabolite levels in late gestation, except plasmatic urea which decreased in third-parity sows with FL. In lactation, plasma urea level increased with CP (P<0.05) in second-parity sows, and on increasing FL (P<0.05), in third-parity sows (P<0.05). The proportion of pigs born alive was not affected by the sows’ nutritional treatment. In second-parity sows, treatment did not affect total litter weight at birth or at weaning. On the contrary, in third-parity sows, total litter weight at birth increased on increasing dietary CP content (P<0.05). Also, total litter weight at weaning tended to increase in third-parity sows fed the highest FL (P=0.073). Pig BW at weaning was 8.09±0.110 and 8.05±0.135kg, respectively in the second- and third-parity sows. In conclusion, a daily provision of at least 2.67kg of the diet containing 120g CP/kg to the IB sow during the last third of pregnancy ensures adequate nutrient supply to fetuses and body reserves for lactation. This feeding regime provides 33.4MJ ME and 247g apparent digestible protein.

The effect of level of crude protein and available lysine on finishing pig performance, nitrogen balance and nutrient digestibility.

Two trials were conducted to investigate the effect of decreasing the crude protein (CP) content of diets for finishing pigs containing two levels of available lysine on nutrient digestibility, nitrogen (N) balance and production performance. Ten finishing diets containing five levels of CP (on average 144, 155, 168, 182 and 193 g/kg fresh basis) and two levels of available lysine (6.9 and 8.2 g/kg fresh basis) were formulated. The diets were offered to pigs on a performance trial (n = 800 Large White (LW)×Landrace (LR) pigs) from 10 wk of age until finish at 21 wks+5 d of age. Average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) were calculated. In addition, a digestibility/N balance trial was conducted using pigs (n = 80 LW×LR) housed in metabolism crates. Digestibility of dry matter (DM), CP, oil, fibre and energy was determined. N balance values were determined through analysis of N content of urine and faeces (‘as determined’). N balance values were also calculated using ADG values and assuming that 16% of growth is protein deposition (“as calculated”). Pig performance was poor between 10 and 13 wk of age which indicated that the dietary treatments were nutritionally inadequate for pigs less than 40 kg. There was a significant (p<0.01) quadratic effect of increasing CP level on feed intake, ADG and FCR from 10 to 13 wk which indicated that the lower CP levels did not supply adequate levels of essential or non-essential amino acids. There was no effect of increasing available lysine level throughout the early period, which in conjunction with the response in older pigs, suggested that both 8.2 and 6.9 g/kg available lysine were insufficient to drive optimum growth. There was a positive response (p<0.05) to increasing available lysine level from 13 wk to finish which indicated that 6.9 g/kg available lysine was not adequate for finishing pigs. Energy digestibility decreased with decreasing CP level of diets containing 6.9 g/kg available lysine which may be attributed to the higher fibre content of the lower CP diets. Nitrogen excretion (g/d) was lowered when dietary CP was reduced regardless of whether the values were determined through balance or calculated using ADG. Calculated N excretion decreased linearly (p<0.001) and quadratically (p<0.001) with decreasing dietary CP content. When the N balance figures calculated in this study were compared with those quoted in the Northern Ireland and English Nitrates Directive Action Programmes, N excretion was less per pig (wean to finish) offered a 169 g/kg CP, 8.2 g/kg available lysine diet (2.39 kg vs 3.41 kg (Northern Ireland) and 2.93 kg (England)).

Partial replacement of starch with acid detergent fibre and/or neutral detergent soluble fibre at two protein levels: Effects on ileal apparent digestibility and caecal environment of growing rabbits

The effects of the composition of peri-weaning diets on apparent ileal digestibility of nutrients and caecal environment were studied in growing rabbits. Eight diets were formulated according to a 2×2×2 factorial design to increase acid detergent fibre (ADF) from 230 to 290gkg−1 dry matter (DM) at the expense of mainly starch, to increase neutral detergent soluble fibre (NDSF) from 145 to 185gkg−1 DM at the expense of mainly starch, and to reduce crude protein (CP) content from 175 to 145gkg−1 DM. A total of 32 litters of eight kits were randomly assigned to the diets at 17 days of age, weaned at 28 days of age and slaughtered at 35 days of age to collect samples of ileal and caecal contents. The substitution of ADF for starch reduced the coefficient of apparent ileal digestibility (CAID) of DM (0.292 vs. 0.229; P<0.01). The substitution of NDSF for starch increased the CAID of NDSF (−0.040 vs. 0.099; P<0.01). An interaction between dietary ADF and NDSF levels was found for the CAID of CP, higher in the low ADF-low NDSF diets than in the rest (+0.074; P<0.05). The reduction of dietary CP content decreased the CAID of CP (0.578 vs. 0.525; P<0.05) and NDSF (0.086 vs. −0.038; P<0.01). Interactions between dietary ADF and NDSF levels were found affecting full caecum weight as well as DM content and pH of caecal digesta. The increase of ADF in the high NDSF diets reduced full caecum weight (−9.1gkg−1 live weight; P<0.01), increased DM content of caecal digesta (+31gkg−1; P<0.001) and reduced caecal pH (−0.10; P<0.05). In the low NDSF diets, higher ADF increased DM content of caecal digesta to a lesser extent (+16gkg−1; P<0.001) and increased caecal pH (+0.08; P<0.05). The increase of NDSF in the high ADF diets increased full caecum weight (+8.5gkg−1 live weight; P<0.01) and reduced caecal pH (−0.14; P<0.001). In the low ADF diets, higher NDSF increased full caecum weight more extensively (+15.5gkg−1 live weight; P<0.001) and reduced DM content of caecal digesta (−16gkg−1; P<0.001). Both ADF and NDSF replacing starch increased total volatile fatty acid (VFA) concentration of caecal digesta (+11.5% and +13.9%, respectively; P<0.01). The replacement with NDSF increased molar proportion of butyrate (0.095 vs. 0.112; P<0.001) at the expense of mainly acetate (0.841 vs. 0.820; P<0.001) and reduced ammonia concentration of caecal digesta (−8.1%; P<0.05). The reduction of dietary CP content decreased total VFA (−14.4%; P<0.001) and ammonia (−23.5%; P<0.001) concentrations of caecal digesta and increased caecal pH (5.87 vs. 5.93; P<0.05). Overall, the three dietary changes under study led to changes in the caecal environment which might be effective in reducing mortality rate in a context of rabbit epizootic enteropathy.