Dietary Crude Protein Content Research Articles

139 Effect of dietary crude protein concentration and sensory feed additive on nursery pig growth performance

Abstract Maximizing growth performance and feed intake for nursery pig diets is an ongoing challenge in the US swine industry. Using sensory feed additives is one strategy to optimize feed intake and growth rates of pigs. Weanling pigs (n = 416; average age = 19.8 d) were used to test the effects of sensory feed additive (SA; Luctamax Piglet, Lucta, Mahwah, NJ) addition to control (CON) and low crude protein (LCP; decreased 4% CP) nursery diets in a 2 x 2 factorial design (CON, CON+SA, LCP, LCP+SA). Decreased dietary CP was achieved by removing or decreasing fish meal and soy concentrate in phases 1 and 2 and reducing soybean meal in phase 3 and adding synthetic amino acids to maintain amino acid ratios (NRC 2012). Nursery treatments were fed in three phases; phase 1 (PH1, d 0-7, 0.10% SA), phase 2 (PH2, d 7-21, 0.10% SA), and phase 3 (PH3, d 21-36, 0.05% SA). Pigs were blocked by initial body weight (BW), sex, ancestry, and housed at 6 or 7 pigs/pen with 15 pens/treatment. Weekly pig BW and feed intake were used to calculate pen average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). Data were analyzed using GLM procedure of SAS 9.4. During PH1 pigs receiving the CON diets tended (P = 0.065) to have a greater G:F compared with pigs receiving LCP diets. For the remainder of this study there were consistent interactions between dietary CP and SA. When SA was added to the LCP diet ADFI increased but when SA was added to CON diet ADFI decreased and these changes in feed intake often led to similar dietary interactions in ADG. During PH2, pigs fed CON or LCP+SA diets had greater ADFI (P = 0.032) and tended to have a greater ADG (P = 0.094) but reduced G:F (P = 0.100) compared with pigs fed CON+SA or LCP diets. In PH3, pigs fed CON or LCP+SA diets had a greater ADG (P = 0.027) and ADFI (P = 0.011) compared with CON+SA or LCP diets. Pigs fed LCP diets had greater ADFI (P = 0.001) but reduced G:F (P = 0.0001) than pigs fed CON diets. Overall, pigs fed CON or LCP+SA diets had greater ADFI (P = 0.016) and tended to have a greater ADG (P = 0.059) but reduced G:F (P = 0.067) compared with pigs fed CON+SA or LCP diets. Pigs fed CON diets had a greater G:F (P < 0.001) compared with pigs fed LCP diets, while LCP pigs tended to have a greater ADFI (P = 0.054) compared with CON pigs. Inclusion of SA to LCP diet mitigated the adverse impact of replacing whole dietary proteins with high inclusion of synthetic amino acids. Careful consideration is needed when using sensory feed additives so as not to impede growth performance in diets containing traditionally greater levels of crude protein.

Crude protein content in diets associated with intestinal microbiome and metabolome alteration in Huanjiang mini-pigs during different growth stages.

Adequate crude protein (CP) content in diets plays a crucial role in the intestinal health of the animal. This study investigated the impacts of CP content in diets on the intestinal microbiome and metabolome profiles in growing Huanjiang mini-pigs. A total of 360 pigs with similar body weight (BW) were allocated for three independent feeding trials based on three different BW stages, including (i) 5-10 kg BW, diets consisting of 14, 16, 18, 20, and 22% CP content; (ii) 10-20 kg BW, diets consisting of 12, 14, 16, 18, and 20% CP content; and (iii) 20-30 kg BW, diets consisting of 10, 12, 14, 16, and 18% CP content. These experiments lasted 28, 28, and 26 days, respectively. The results showed that the Shannon and Simpson indices were decreased (p < 0.05) in the ileum of pigs in response to the 14-18% CP compared with the 20% CP content at 5-10 kg BW stage, while diets containing 12 and 14% CP had higher Chao1 (p < 0.05) and Shannon (p = 0.054) indices compared with 18% CP at 20-30 kg BW stage. Compared with the 20% CP, the diet containing 16% CP displayed an increasing trend (p = 0.089) of Firmicutes abundance but had decreased (p = 0.056) Actinobacteria abundance in the jejunum at 5-10 kg BW stage. In addition, a diet containing 16% CP had higher Lactobacillus abundance in the jejunum and ileum compared with the 18, 20, and 22% CP, while had lower Sphingomonas and Pelomonas abundances in the jejunum and Streptococcus abundance in the ileum compared with the diet containing 22% CP (p < 0.05). Diets containing lower CP content altered differential metabolites in the small intestine at the early stage, while higher CP content had less impact. These findings suggest that a diet containing lower CP content (16% CP) may be an appropriate dietary CP content for 5-10 kg Huanjiang mini-pigs, as 16% CP content in diet has shown beneficial impacts on the intestinal microbiome and metabolome profiles at the early growth stage of pigs.

Effects of Individual Essential Amino Acids on Growth Rates of Young Rats Fed a Low-Protein Diet.

To investigate the effects of individual essential amino acids (EAA) on growth and the underlying mechanisms, EAA individually supplemented a low-protein (LP) diet fed to young rats in the present study. Treatments were an LP diet that contained 6% crude protein (CP), a high-protein (HP) diet that contained 18% CP, and 10 LP diets supplemented with individual EAA to achieve an EAA supply equal to that of the HP diet. The CP concentration of the LP diet was ascertained from the results of the first experiment, which examined the effects of dietary CP concentrations on growth rates, with CP ranging from 2% to 26%. Weight gain was increased with the supplementation of His, Ile, Lys, Thr, or Trp as compared to the LP diet (p < 0.05). Feed intake was greater for the His-, Lys-, and Thr-supplemented treatments as compared to the LP group (p < 0.05). Protein utilization efficiency was lower for the HP group than other groups (p < 0.01). The supplementation of Leu, Lys, and Val led to reduced protein utilization efficiency (p < 0.05), but the supplementation of Thr and Trp led to greater efficiency than the LP group (p < 0.05). Compared to the LP group, plasma urea concentrations were elevated with individual EAA supplementation, with the exception of the Thr addition. The added EAA resulted in increased concentrations of the corresponding EAA in plasma, except for Arg and Phe supplementation. The supplementation of Arg, His, Leu, Lys, and Met individually stimulated mTORC1 pathway activity (p < 0.05), and all EAA resulted in the decreased expression of ATF4 (p < 0.05). In summary, the supplementation of His, Ile, Lys, Thr, or Trp to an LP diet improved the growth performance of young rats. Responses to His and Lys additions were related to the activated mTORC1 pathway and feed intake increases. The improved growth performance resulting from the addition of a single EAA is not solely attributed to the increased plasma availability of EAA. Rather, it may be the consequence of a confluence of factors encompassing signaling pathways, the availability of amino acids, and other associated elements. The additivity of these factors results in independent responses to several EAA with no order of limitation, as is universally encoded in growth models for all production animal species.

Relationships between Dietary Chemical Components and Enteric Methane Production and Application to Diet Formulation in Beef Cattle

We used published data consisting of 263 treatment mean observations from beef cattle and dairy steers and heifers, in which CH4 was measured via chambers or head boxes, to evaluate relationships between enteric CH4 production and dry matter intake (DMI) and dietary components. Daily DMI was positively related (slope = 15.371, p &lt; 0.001) to total daily production (g/d) of CH4 (r2 = 0.821). Among chemical components, dietary neutral detergent fiber (NDF) concentration was the most highly related (r2 = 0.696; slope = 0.2001; p &lt; 0.001) to CH4 yield (g/kg of DMI), with strong relationships also noted for dietary starch:NDF ratio (r2 = 0.662; slope = −2.4587; p &lt; 0.001), starch (r2 = 0.495; slope = −0.106; p &lt; 0.001), and the proportion of metabolizable energy relative to gross energy (r2 = 0.561; slope = −23.663; p &lt; 0.001). The slope (−0.5871) and intercept (22.2295) for the dietary ether extract vs. CH4 yield were significant (p &lt; 0.001), but the relationship was highly variable (r2 = 0.150). For dietary crude protein concentration, the slope for CH4 yield was not significant (−0.0344; p &lt; 0.381) with an r2 value near zero. Decreasing DMI by programming body weight gain or restricting feed intake could decrease CH4 production in confined cattle, but these approaches might negatively affect growth performance and product quality, potentially negating positive effects on CH4 production. Feeding higher-quality forages or using grazing management systems that decrease dietary NDF concentrations or substituting grain (starch) for forage should decrease both CH4 yield from enteric production and manure CH4 production via increased digestibility. Effects of feeding management and diet formulation strategies should be additive with other mitigation approaches such as feed additives, allowing the cattle industry to achieve maximal decreases in enteric CH4 production, while concurrently maintaining optimal beef production.

Reducing dietary protein and supplementation with starch or rumen-protected methionine and its effect on performance and nitrogen efficiency in dairy cows fed a red clover and grass silage-based diet

The increasing cost of milk production, in association with tighter manure N application regulations and challenges associated with ammonia emissions in many countries has increased interest in feeding lower crude protein (CP) diets based on legume silages. Most studies have focused on alfalfa silage, and there is a lack of information on low CP diets based on red clover silage. Our objectives were to examine the effects of dietary CP content and supplementing a low CP diet with dietary starch or rumen-protected Met (RPMet) on the performance, metabolism, and nitrogen-use-efficiency (NUE; milk N output/N intake) in dairy cows fed a red clover and grass silage-based diet. Fifty-six Holstein-Friesian dairy cows were blocked and randomly allocated to 1 of 4 diets over a 14-week feeding period. Diets were based on red clover and grass silages at a ratio of 50:50 (dry matter (DM) basis) and were fed as a total mixed ration, with a forage-to-concentrate ratio of 53:47 (DM basis). The diets were formulated to supply a similar metabolizable-protein (MP) content, and have a CP concentration of 175 g/kg DM (CON), or 150 g/kg DM (LP = low protein), or LP supplemented with additional barley as a source of starch (+ 64 g/kg DM; LPS) or RPMet (+ 0.3 g/100 g MP; LPM). At the end of the 14-week feeding period, 20 cows (5 per treatment) continued to be fed the same diets for a further 6 d, and total urine output and fecal samples collected. We observed that dietary treatment did not affect DM intake, with a mean of 21.5 kg/d, however, there was an interaction between diet and week with intake being highest in cows fed LPS in wk 4 and CON in wk 9 and 14. Mean milk yield, 4% fat corrected milk and energy corrected milk were not altered by treatment. Similarly, we found no effect of dietary treatment on milk fat, protein or lactose content. In contrast, milk and plasma urea concentrations were highest in cows fed CON. The concentration of blood plasma β-hydroxybutyrate was highest in cows receiving LPM and lowest in LPS. Apparent NUE was 28.6% in cows fed CON, and was higher in cows fed any of the low protein diets (LP, LPS or LPM) with a mean value of 34.2%. The sum of milk fatty acids with a chain length below C16:0 was also highest in cows fed CON. We observed that dietary treatment did not affect the apparent whole-tract nutrient digestibility of organic matter, N, neutral detergent fiber and acid detergent fiber, with mean values of 0.785, 0.659, 0.660 and 0.651 kg/kg respectively, but urinary N excretion was approximately 60 g/d lower in cows fed the low CP diets compared with CON. We conclude that reducing the CP content of red clover and grass silage-based diets from 175 to 150 g/kg DM while maintaining MP supply did not affect performance, but reduced the urinary N excretion and improved NUE, and that supplementing additional starch or RPMet had little further effect.

PSXI-16 Nitrogen Excretion and Urine Ph in Growing Pigs Decreased By Reducing Dietary Protein Concentrations

Abstract The objective of the present work was to determine effects of reducing dietary crude protein (CP) concentrations with indispensable amino acid (AA) supplementation on nitrogen balance and urinary pH in growing pigs. Three experiments were conducted using 12 barrows with an initial body weight of 29.9, 50.2, and 78.2 kg (standard deviation = 1.8, 2.2, and 3.7, respectively) individually housed in metabolism crates. In each experiment, a quadruplicated 3 × 2 incomplete Latin square design with 3 diets varying CP concentrations in each experiment and 2 periods per square was employed. In experiments 1 and 2, experimental diets based on corn, soybean meal, corn distillers dried grain with solubles, and rapeseed meal were formulated to contain 16.8, 15.0, and 13.2% CP as-fed basis and 16.8, 14.9, and 13.1% CP as-fed basis, respectively. In experiment 3, experimental diets based on corn and soybean meal were formulated to contain 15.1, 13.2, and 11.4% CP as-fed basis. All diets were supplemented with indispensable AA to meet all indispensable AA requirements. Each period consisted of a 5-day adaptation period followed by a 4-day collection period. On days 6 and 10, chromic oxide was added at 0.5% in morning meals as a marker and the marker-to-marker procedure was used for the quantitative collection of feces. Urine collection was initiated at 10:00 on day 6 and terminated at 10:00 on day 10. Polynomial contrasts were performed to test linear and quadratic effects of dietary CP concentrations on the response variables in each experiment. In all experiments, daily N intake was linearly decreased (P &amp;lt; 0.05) with decreasing dietary CP concentrations. Decreasing dietary CP concentrations resulted in linear reduction in daily fecal N excretion (P &amp;lt; 0.05) in experiment 2 and linear reductions in daily urinary N excretion (P &amp;lt; 0.05) in all experiments. Total N excretion linearly decreased (P &amp;lt; 0.05) with decreasing dietary CP concentration in all experiments. The urinary pH obtained from 30- and 50-kg pigs was linearly decreased (P &amp;lt; 0.05) with decreasing dietary CP concentrations. In conclusion, lowering dietary CP concentrations decreased N excretion and urinary pH in 30-, 50-, and 78-kg pigs.

209 Lowering Dietary Crude Protein Concentration Decreases Nitrogen Excretion and pH of Urine and Slurry in 15-kg Nursery Pigs

Abstract The objective of the present work was to determine the effects of reucing dietary crude protein (CP) concentrations with essential amino acid (EAA) supplementation on nitrogen balance, urinary pH, and slurry pH in nursery pigs. Twelve barrows with an initial body weight of 15.2 kg (standard deviation = 0.7) were individually housed in metabolism crates. A quadruplicated 3 × 2 incomplete Latin square design with 3 experimental diets and 2 periods per square was employed. Experimental diets based on corn, soybean meal, whey powder, fish meal, and blood plasma were formulated to contain 19.4% CP, 17.5% CP, and 15.7% CP by reducing inclusion rates of soybean meal. All experimental diets were supplemented with EAA to meet all EAA requirements. Each period consisted of a 4-day adaptation period and a 24-hour collection period followed by a 4-day collection period. On day 5, feces and urine were collected for 24 h and the feces and urine were mixed in a ratio of fecal weight and urine weight at the end of collection to obtain slurry samples. Then, pH of urine and slurry samples was measured immediately. On days 6 and 10, chromic oxide was added at 0.5% in morning meals as a marker and the marker-to-marker procedure was used for the quantitative collection of feces. Urine collection was initiated at 1000 h on day 6 and terminated at 1000 h on day 10. Orthogonal polynomial contrasts were performed to test linear and quadratic effects of dietary CP concentrations on the response variables. Daily N intake was linearly decreased with decreasing dietary CP concentrations (P &amp;lt; 0.05). Daily fecal and urinary N excretions linearly decreased with decreasing dietary CP concentrations (P &amp;lt; 0.05), whereas N retention rate as % of intake was linearly increased with decreasing dietary CP concentrations (P &amp;lt; 0.05). The urine pH and slurry pH were linearly decreased with decreasing dietary CP concentrations (P &amp;lt; 0.05). In conclusion, lowering dietary CP concentrations decreased N excretion and pH of urine and slurry.

Influence of Diet and Dietary Crude Protein Content on the Reproductive Performance of the Snail Archachatina marginata (Swainson, 1821)

The pressure to collect snails due to the high demand for their meat has encouraged snail farming. However, snail farming faces a number of problems, including the formulation of a feed that meets the nutritional requirements of snails. The aim of this study was to evaluate the influence of plant-based diets and three concentrated diets, and then to determine the protein level to be incorporated into a concentrated feed capable of positively influencing the reproductive performance of the Archachatina marginata snail. The study was conducted on 225 Arch. marginata juveniles fed two plant-based diets (R1 and R2) and 3 concentrated meal diets (R3, R4 and R5) with different protein contents (10.5%, 14% and 17.5%) for two years in experimental rearing. The R1 diet consists of Lactuca sativa, Carica papaya, Brassica oleracea, Cecropia peltata, Laportea aestuans and Phaulopsis falcisepala. The R2 diet was obtained by adding Leucena leucocephala leaves to R1. The first eggs were laid at 12 months on the R1 and R2 green forage diets and at 10 months on the R3 concentrate diet. Snails fed concentrated diets R4 and R5 laid their eggs at 9 months. The number of eggs laid per clutch and the average number of eggs per clutch in the animals fed the concentrated diets were statistically higher than those obtained with the vegetable diets (between 0.34 and 0.45 clutches and between 6.10 and 7.46 eggs respectively). The concentrated diets significantly improved the reproductive performance of Arch. marginata compared with the vegetable diets. In addition, reproductive performance was optimal on the R5 diet with the highest protein incorporation rate.

The influence of dietary crude protein concentrations, grain types and arginine:lysine ratios on the performance of broiler chickens.

The objective of this study was to investigate the effects of dietary crude protein (CP) concentrations, grain types and arginine:lysine ratios on performance parameters of broiler chickens. The 2×2×2 factorial array of dietary treatments harnessed two CP concentrations (210 and 170g/kg), two feed grains (wheat and sorghum), and two arginine:lysine ratios (104 and 110). Each dietary treatment was offered to 7 replicates of 14 birds per floor pen, a total of 784 off-sex male, Ross 308 broilers, from 14 to 35d post-hatch. The dietary CP reduction compromised weight gain by 10.0% (2078 versus 2310g/bird) as a main effect and FCR by 7.51% (1.474 versus 1.371), subject to an interaction. In a three-way interaction (P=0.008), expanded arginine:lysine ratios improved FCR by 2.30% in 170g/kg CP, sorghum-based diets but compromised FCR by 2.12% in corresponding wheat-based diets. Sorghum was the more suitable feed grain in reduced-CP diets as sorghum generated significant advantages in weight gain of 7.59% (2154 versus 2002g/kg) and FCR of 6.94% (1.421 versus 1.527) in birds offered 170g/kg CP diets. Both dietary CP and feed grain generated significant and divergent impacts in apparent ileal digestibility coefficients for the majority of 16 assessed amino acids. Dietary CP reductions increased non-bound amino acid inclusions (NBAA) in wheat-based diets (48.96 versus 9.80g/kg) to a greater extent than sorghum-based diets (35.3 versus 9.50g/kg) and increasing dietary NBAA inclusions were linearly associated with compromised weight gain (r=-0.834; P<0.001) and FCR (r=0.862; P<0.001). Increasing ratios of free arginine to lysine plasma concentrations were linearly (r=-0.466; P=0.004) related to improvements in FCR. The implications of the observed outcomes are discussed and possible explanations are advanced.

Effect of reduced crude protein diets supplemented with free limiting amino acids on body weight, carcass yield, and breast meat quality in broiler chickens

This study investigated the effect of reducing dietary crude protein (CP) content in the grower and finisher diets of broiler chickens on breast meat quality, muscle protein functionality, growth, carcass yield, and meat yield. To achieve this, a total of 1,269 one-day-old male Ross 308 chicks were fed 1 of 3 diets replicated 9 times each in a randomized complete block design with 9 blocks. The diets included a control (20.4% and 19.5% CP in the grower and finisher phase, respectively), a diet with a 1.5% reduction (CP-1.5%) and a diet with a 3.0% reduction (CP-3.0%) in CP content in both the grower and finisher phases. At the end of the experiment, the reduced-CP diets had no impact on body weight, feed intake, or feed conversion ratio. However, reduced-CP diet resulted in reduced (P < 0.001) total nitrogen intake (-7.46 and -11.94% in CP-1.5% and CP-3.0%, respectively). Breast meat quality was assessed (n=36 birds/group), and the experimental diets were associated with a slightly increased (P=0.07) ultimate pH (5.75, 5.79, and 5.81 for the control, CP-1.5%, and CP-3.0%, respectively). Breast fillets from the CP-1.5% and CP-3.0% groups had lower yellowness (b*, P < 0.001) and lower cooking loss (CL, P < 0.001) values than the control. Moreover, the solubility, emulsion activity, and stability indices of the sarcoplasmic and myofibrillar fractions of muscle proteins were not influenced by the diets. CP-1.5% and CP-3.0% diets were associated with an increased (P < 0.001) breast yield (18.39, 19.21, and 19.61% for the control, CP-1.5%, and CP-3.0%, respectively) while leg yield remained unchanged. Additionally, breast meat nutritional properties including protein and lipid contents were not impacted by the experimental diets. In conclusion, the CP content in the grower and finisher diets of broiler chickens can be reduced by as much as 3.0% without detrimental effects on performance or on meat quality as long as birds' amino acid requirements are adequately met.

78. Life cycle analysis of pig production – Effect of a reduction in dietary crude protein content and the origin of amino acids – Case study in northern Germany

78. Life cycle analysis of pig production – Effect of a reduction in dietary crude protein content and the origin of amino acids – Case study in northern Germany

The influence of substituting dietary peptide-bound with free amino acids on nitrogen metabolism and acid-base balance of broiler chickens depends on asparagine and glutamine supply.

Reducing dietary crude protein (CP) concentration while maintaining adequate amino acid (AA) supply by free AA inclusion can contribute to attenuate the negative environmental effects of animal farming. This study investigated upper limits of dietary free AA inclusions without undesirable effects including the dependence on asparagine (Asn) and glutamine (Gln) supply. Ten broilers were allocated to sixty-three metabolism units each and offered nine experimental diets from day (d) 7-21 (n 7). One diet (167 g CP/kg) contained 80 g soya protein isolate (SPI)/kg. In the other diets, 25, 50, 75 and 100 % of the digestible AA from SPI were substituted with free AA. Digestible Asn+aspartic acid (Asp) and Gln+glutamic acid (Glu) were substituted with Asp/Glu or 50/50 mixes of Asp/Asn and Glu/Gln, respectively. Total excreta were collected from d 11-14 and from d 18-21. Growth and nitrogen accretion were unaffected by 25 and 50 % substitution without and with free Asn/Gln, respectively, but decreased at higher substitution (P ≤ 0·024). Circulating concentrations of Asp, Glu and Gln were unaffected by treatment, while Asn decreased at substitution higher than 50 % when Asn/Gln were not provided (P ≤ 0·005). Blood gas analysis on d 21 indicated a compensated metabolic acidosis at substitution higher than 50 and 75 % without and with free Asn/Gln, respectively (P ≤ 0·017). Results suggest that adding Asn/Gln increased an upper limit for proportion of dietary free AA from 10 to 19 % of dietary CP and enabled higher free AA inclusion without affecting the acid-base balance.

P66 Impact of dietary crude protein concentration in dairy cow diets on nitrogen use efficiency and relationships with residual feed intake

P66 Impact of dietary crude protein concentration in dairy cow diets on nitrogen use efficiency and relationships with residual feed intake

Performance characteristics and digestion of growing rabbits fed Corn Gluten Residue Meal (CGRM), Soybean Gluten Residue Meal (SGRM), and Sorghum Brewer Dry Grain (SBDG)

Context: Grain by-products are nonconventional feed resources that can be used as supplemental diets for rabbits, especially during the dry season when native forages are scarce and limiting in essential nutrients. Hence, this present study is to determine the inclusion of residue, Corn Gluten Residue Meal (CGRM), Soybean Gluten Residue Meal (SGRM), and Sorghum Brewer Dry Grain (SBDG) as a replacement for maize on the performance and digestion coefficient of growing rabbits. Methods: Forty mixed breeds of rabbits (4 - 6 weeks old) were allotted into four experimental treatments in a completely randomized design. Four experimental diets were then compounded by replacing maize (40% inclusion level) with CGRM, SGRM, and SBDG then fed to the growing rabbits at 3% of their body weight. Results: The crude protein contents of diets containing grain by-products (19.06% – 20.87%) were better than maize (12.96%). Evidently, the maize diet (55.56%) was higher in carbohydrate fraction than these grain by-product-containing diets (42.20 – 49.98). Rabbits fed diets containing grain by-products had significantly higher (p &lt; 0.05) feed intake and final weight compared to rabbits fed maize. Rabbits-fed diets containing CGRM (87.41%) and SGRM (92.09%) were significantly higher (p &lt; 0.05) in digestible crude protein than maize (76.79%) and SBDG (74.29%) diets. Also, diets containing maize and SGRM were significantly higher (p &lt; 0.05) in the digestible carbohydrate fraction than diets. Whereas, rabbits fed diets CGRM and SBDG had significantly better (p &lt; 0.05) nitrogen balance and retention compared to rabbits fed diet SGRM and maize. Conclusion: It could be concluded that the inclusion of CGRM, SGRM, and SBDG led to better performances and digestion but with inferior carbohydrate fractions and digestion percentages compared to the maize diet.

Management factors affecting the environmental impact of cereal-based dairy farms

This study aimed to assess the environmental impact (cradle-to-farm gate LCA) of milk production of cereal-based dairy farms in northern Italy and to analyse which traits related to farm management (MAN_F), lactating cows’ ration composition (DIET_F), and animal responses (ANI_F) could be identified as main determinants to address specific mitigation strategies. Data originated from 28 dairy farms. The functional unit was 1 kg of fat- and protein-corrected milk (FPCM). Impact categories were global warming (GWP), acidification (AP) and eutrophication (EP) potentials and land occupation (LO). Impact values were analysed with a linear model to test separately the effects of MAN_F, DIET_F and ANI_F variables. One kg FPCM was associated with an average impact of 1.10 kg CO2-eq (GWP), 17.1 g SO2-eq (AP), 6.0 g PO4-eq (EP), and 1.3 m2/y (LO). Regarding MAN_F, GWP and LO linearly decreased with increasing values of stocking rate and feed self-sufficiency (FSS), whereas minimum EP was found for intermediate FSS values (50% DM). Regarding DIET_F, GWP linearly decreased at increasing levels of dietary inclusion of cereal silages, whereas AP and EP linearly decreased at decreasing dietary crude protein (CP) content values. Among ANI_F, GWP and EP were quadratically associated with milk yield (MY), evidencing the lowest values at intermediate MY (9100 ± 477 kg FPCM/cow per 305d-lactation). The GWP, AP and EP decreased with decreasing age at first calving. These results can contribute at drawing good practices for farmers and consultants to promote more environmentally sustainable dairy production while supporting farm functioning and farmers’ income. HIGHLIGHTS Farm and animal determinants of Life Cycle Assessment of cereal-based dairy farms were studied. Mitigation effects can be achieved by operating on farm organisation, cow’s diet, and animal responses. Good practices for farmers and consultants can be proposed for a better dairy production sustainability.

Performance of dairy cows offered high or low digestibility grass silages at a high or low total diet crude protein content

Performance of dairy cows offered high or low digestibility grass silages at a high or low total diet crude protein content

Implementing IPCC 2019 Guidelines into a National Inventory: Impacts of Key Changes in Austrian Cattle and Pig Farming

This study examined enteric and excreta emissions from cattle and pigs with a focus on effects of changed feeding practices. We assessed the impact of a revision of the Austrian Greenhouse Gas and Air Pollutant Inventory (national method, NM), i.e., the implementation of the Tier2-method of the IPCC-2019 guidelines, to a more dynamic integration of past and present feeding practices. Cattle—in particular, dairy cows—had the highest contribution to enteric CH4 emissions and to nitrogen (Nex) and volatile-solid (VSex) excretion, independent of the assessment method (NM or IPCC-2019). These emissions as well as excreta quantities are directly associated with feeding. The most relevant changes from implementing IPCC-2019 were (i) reduced enteric CH4 over the entire time series and (ii) increased Nex and VSex, especially for the period from 1990 to 2005. Additionally, uncertainties in the emissions and excreta were analyzed and related to the quantities of protein consumed. From 1990 to 2020, favorable trends per unit of protein were shown due to increased performance and concomitantly reduced animal numbers. The changes were especially pronounced for CH4, Nex, and VSex from dairy cows (−40% to −46%) but also substantial for other cattle (−26% to −31%), breeding pigs (−12% to −28%), and partially growing-fattening pigs (−3% to −20%). Future mitigation potential may result from reduced dietary crude-protein content, especially in pigs, and the use of feed additives. Feed additives for ruminants with enteric CH4-mitigating effects showed a particularly high reduction potential for the total amount of greenhouse gases from the livestock sector.

Impacts of Dietary Lysine and Crude Protein on Performance, Hepatic and Renal Functions, Biochemical Parameters, and Histomorphology of Small Intestine, Liver, and Kidney in Broiler Chickens

The present study aimed to investigate the effects of increasing dietary lysine (Lys) levels with an adequate dietary crude protein (CP) content, as well as the effects of a reduction in dietary CP content with the recommended amino acid (AAs) level, on the performance, blood biochemical parameters, and histomorphology of the duodenum, liver, and kidney in broiler chickens. A total of 500 broiler chickens were randomly distributed into five dietary treatment groups, following a completely randomized design, where, at the beginning, the control group (C) was fed a diet containing the standard CP and Lys levels: 23% CP with 1.44% Lys during the starter period; 21.5% CP with 1.29% Lys during the growing period; and 19.5% CP with 1.16% Lys during the finishing period. The Lys content was increased by 10% above the recommended control basal requirements in the second group (Gr1) and by 20% in the third group (Gr2), while using the same recommended CP percentage as the C group. The fourth group (Gr3) had a 1% lower CP content and the fifth group had a 2% lower CP content than the C group, with the same recommended AA level as the C group. Increasing the Lys content in the Gr1 group improved the broilers' weight gains (p < 0.05) during the starter, growing, and finishing periods. Decreasing dietary CP with the standard AA levels (Gr3 and Gr4) did not significantly affect (p > 0.05) the live weight gain, feed intake, or feed conversion ratio (FCR) of the broilers compared with those fed with the C diet. Blood total bilirubin, direct and indirect bilirubin, triglycerides, cholesterol, low-density lipoprotein (LDL), and very LDL were not different among the experimental groups. However, blood aspartate aminotransferase levels were increased (p < 0.05) in the Gr1 and Gr3 groups compared with the other treatment groups. All dietary treatments decreased the serum creatinine levels (p < 0.05) compared with the C group. The Gr2 broilers had greater serum total protein and globulin (p < 0.05) than those receiving the other treatments. Increasing dietary Lys levels resulted in a significant improvement in duodenum villus height and width (p < 0.05), while the low-CP diets resulted in shorter villi length and width, along with degenerated areas and lymphocytic infiltration. Low dietary CP content induced hepatocyte disorganization and moderate degeneration, along with vacuolated hepatic cells, excessive connective tissue, and lymphocytic infiltration. The cortical regions of the kidney exhibited obvious alterations in the Gr3 and Gr4 groups and large interstitial spaces were found between tubules. Renal tubules in the Gr3 and Gr4 groups were smaller in size and some of these tubules were atrophied. In conclusion, reducing dietary CP levels to 1% or 2% lower than the recommended level did not negatively affect growth performance, inducing minimal influence on the blood metabolic indicators of health status, and resulting in moderate alterations to the histomorphology of the duodenum, liver, and kidney. Furthermore, increasing the Lys content by 10% above the recommended level improved the growth performance, health status, and histomorphology of the duodenum, liver, and kidney in broiler chickens.

Feeding lower-protein diets based on red clover and grass or alfalfa and corn silage does not affect milk production but improves nitrogen use efficiency in dairy cows

Reducing the dietary crude protein (CP) concentration can decrease the financial cost and lower the environmental impact of milk production. Two studies were conducted to examine the effects of reducing the dietary CP concentration on animal performance, nutrient digestibility, milk fatty acid (FA) profile, and nitrogen use efficiency (NUE; milk N/N intake) in dairy cows fed legume silage-based diets. Thirty-six multiparous Holstein-Friesian dairy cows that were 76 ± 14 (mean ± SD) days in milk and 698 ± 54 kg body weight were used in a 3 × 3 Latin square design in each of 2 studies, with 3 periods of 28 d. In study 1, cows were fed diets based on a 50:50 ratio of red clover to grass silage [dry matter (DM) basis] containing 1 of 3 dietary CP concentrations: high (H) = 175 g of CP/kg of DM; medium (M) = 165 g of CP/kg of DM; or low (L) = 150 g of CP/kg of DM. In study 2, cows were fed 175 g of CP/kg of DM with a 50:50 ratio of alfalfa to corn silage (H50) or 1 of 2 diets containing 150 g of CP/kg of DM with either a 50:50 (L50) or a 60:40 (L60) ratio of alfalfa to corn silage. Cows in both studies were fed a total mixed ration with a forage-to-concentrate ratio of 52:48 (DM basis). All diets were formulated to meet the MP requirements, except L (95% of MP requirements). In study 1, cows fed L ate 1.6 kg of DM/d less than those fed H or M, but milk yield was similar across treatments. Mean milk protein, fat, and lactose concentrations were not affected by diet. However, the apparent total-tract nutrient digestibility was decreased in cows fed L. The NUE was 5.7 percentage units higher in cows fed L than H. Feeding L also decreased milk and plasma urea concentrations by 4.4 mg/dL and 0.78 mmol/L, respectively. We found no effect of dietary treatment on the milk saturated or monounsaturated FA proportion, but the proportion of polyunsaturated FA was increased, and milk odd- and branched-chain FA decreased in cows fed L compared with H. In study 2, DM intake was 2 kg/d lower in cows receiving L50 than H50. Increasing the alfalfa content and feeding a low-CP diet (L60) did not alter DMI but decreased milk yield and milk protein concentration by 2 kg/d and 0.6 g/kg, respectively, compared with H50. Likewise, milk protein and lactose yield were decreased by 0.08 kg/d in cows receiving L60 versus H50. Diet had no effect on apparent nutrient digestibility. Feeding the low-CP diets compared with H50 increased the apparent NUE by approximately 5 percentage units and decreased milk and plasma urea concentrations by 7.2 mg/dL and 1.43 mmol/L, respectively. Dietary treatment did not alter milk FA profile except cis-9,trans-11 conjugated linoleic acid, which was higher in milk from cows receiving L60 compared with H50. We concluded that reducing CP concentration to around 150 g/kg of DM in red clover and grass or alfalfa and corn silage-based diets increases the apparent NUE and has little effect on nutrient digestibility or milk performance in dairy cows.

Effects of dietary protein content and crystalline amino acid supplementation patterns in low protein diets on intestinal bacteria and their metabolites in weaned pigs raised under Different sanitary conditions.

The objective of this experiment was to investigate the effects of dietary crude protein (CP) content and crystalline amino acids (CAA) supplementation patterns in low CP (LCP) diets on intestinal bacteria and their metabolites in weaned pigs raised under clean (CSC) or unclean sanitary conditions (USC). One hundred forty-four piglets (6.35 ± 0.63 kg) were assigned to one of six treatments in a 3 × 2 factorial arrangement based on CP content and sanitary conditions in a randomized complete block design to give eight replicates with three pigs per pen over a 21-d period. Diets consisted of a high CP (HCP; 21%) and two LCP (18%) diets supplemented with 9 CAA (Lys, Met, Thr, Trp, Val, Ile, Leu, His, and Phe) or only six CAA (Lys, Met, Thr, Trp, Val, and Ile) to meet the requirements. The CSC room was washed weekly, whereas the USC room had sow manure spread in the pens from the beginning of the study and was not washed throughout the experiment. Jejunum and colon digesta were sampled on day 21. Both jejunum and colon digesta were analyzed for ammonia nitrogen, short-chain fatty acids, and biogenic amines but only colon digesta was analyzed for microbiome composition (16s rRNA sequencing on MiSeq). Data were analyzed using R software for 16S rRNA and the MIXED procedure of SAS for microbial metabolites. Sanitation, CP content, and CAA supplementation patterns did not affect the diversity of colonic bacterial composition in weaned pigs. Pigs raised under USC had greater (P < 0.05) jejunal ammonia nitrogen concentration than those raised under CSC. Pigs fed LCP diets had reduced (P < 0.05) jejunal ammonia nitrogen concentration compared to those fed the HCP diet. Interactions between sanitation and dietary CP content were observed (P < 0.05) for: (1) jejunal acetate and (2) colonic spermidine and spermine, whereby (1) acetate concentrations decreased from NCP to LCP in pigs raised under the CSC but those concentrations increased under the USC, and (2) spermidine and spermine concentrations increased in LCP diets compared to HCP diet under USC, unlike CSC which did not show any difference between HCP and LCP. In conclusion, reducing dietary CP lowered ammonia nitrogen content regardless of sanitation and increased microbial metabolites in weaned pigs raised under USC. However, LCP diets with different CAA supplementation patterns did not affect bacterial diversity in weaned pigs, regardless of the hygienic conditions where the animals were housed.