Full-length 16S rRNA gene amplicon analysis of gut microbiota in pigs fed with different diets in growing and finishing stages.

The present study utilized full-length 16S rRNA gene sequencing to investigate the impact of dietary protein content on the composition and function of gut microbiota, and to analyze the gut microbiota of pigs in the growing (30 kg) and finishing (120 kg) stages under different feeding conditions. The results indicated that the gut microbiota was significantly different between pigs fed high- and low-protein diets. Comparing fecal samples from pigs at 30 and 120 kg, pigs at 30 kg showed a significant increase in the relative abundance of Clostridium butyricum, whereas at 120 kg, the abundance of Lactobacillus reuteri and Lactobacillus johnsonii decreased. To access the functional profiles and metabolic pathways based on amplicon sequence variants (ASVs), the microbiome of the 120 kg exhibited significant enrichments in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to metabolism-related category, including Alanine, aspartate and glutamate metabolism, Tyrosine and Thiamin metabolism, and Inositol phosphate metabolism. Meanwhile, analysis using the MetaCyc database showed that the metabolic pathways of the 30 kg group were significantly distinct when compared to the 120 kg of fecal samples. Overall, the findings indicated that the gut microbiota composition and function in the 30 and 120 kg fecal samples were markedly shaped by different dietary protein levels.

Effect of Dietary Crude Protein and Apparent Metabolizable Energy Levels on Growth Performance, Nitrogen Utilization, Serum Parameter, Protein Synthesis, and Amino Acid Metabolism of 1- to 10-Day-Old Male Broilers.

This research compared how different levels of dietary crude protein (CP) and apparent metabolizable energy (AME) affect the growth performance, nitrogen utilization, serum parameters, protein synthesis, and amino acid (AA) metabolism in broilers aged 1 to 10 days. In a 4 × 3 factorial experimental design, the broilers were fed four levels of dietary CP (20%, 21%, 22%, and 23%) and three levels of dietary AME (2800 kcal/kg, 2900 kcal/kg, and 3000 kcal/kg). A total of 936 one-day-old male Arbor Acres broilers were randomly allocated to 12 treatments with 6 replications each. Growth performance, nitrogen utilization, serum parameter, gene expression of protein synthesis, and AA metabolism were evaluated at 10 d. The results revealed no interaction between dietary CP and AME levels on growth performance (p > 0.05). However, 22% and 23% CP enhanced body weight gain (BWG), the feed conversion ratio (FCR), total CP intake, and body protein deposition but had a detrimental effect on the protein efficiency ratio (PER) compared to 20% or 21% CP (p < 0.05). Broilers fed diets with 2800 kcal/kg AME showed increased feed intake (FI) and inferior PER (p < 0.05). Broilers fed diets with 3000 kcal/kg AME showed decreased muscle mRNA expression of mammalian target of the rapamycin (mTOR) and Atrogin-1 compared to those fed diets with 2800 kcal/kg and 2900 kcal/kg AME (p < 0.05). Increasing dietary CP level from 20% to 23% decreased muscle mTOR and increased S6K1 mRNA expression, respectively (p < 0.05). The muscle mRNA expression of Atrogin-1 was highest for broilers fed 23% CP diets (p < 0.05). The mRNA expression of betaine homocysteine methyltransferase (BHMT) and Liver alanine aminotransferase of the 22% and 23% CP groups were higher than those of 20% CP (p < 0.05). Significant interactions between dietary CP and AME levels were observed for muscle AMPK and liver lysine-ketoglutarate reductase (LKR) and branched-chain alpha-keto acid dehydrogenase (BCKDH) mRNA expression (p < 0.05). Dietary AME level had no effect on muscle AMPK mRNA expression for broilers fed 21% and 22% CP diets (p > 0.05), whereas increasing dietary AME levels decreased AMPK mRNA expression for broilers fed 23% CP diets (p < 0.05). The mRNA expression of LKR and BCKDH was highest for broilers fed the diet with 2800 kcal/kg AME and 22% CP, while it was lowest for broilers fed the diet with 3000 kcal/kg AME and 20% CP. The findings suggest that inadequate energy density hindered AA utilization for protein synthesis, leading to increased AA catabolism for broilers aged 1 to 10 days, and a dietary CP level of 22% and an AME level of 2900 to 3000 kcal/kg may be recommended based on performance and dietary protein utilization.

Modeling and optimization of laying hen manure drying process to reduce protein and ammonium-N losses by adding sodium bentonite and wheat straw.

Laying hen manure (LHM) is a major source of pollution due to its high nitrogen (N) and moisture content (MC). Therefore, reducing the MC of LHM is necessary to retain its recyclable value and reduce environmental pollution. One effective way is by incorporating sodium bentonite (SB) and wheat straw (WS) as amendments in the LHM. This work aimed to optimize the drying conditions of LHM and investigate the effect of SB and WS utilization on the dehydration rate, reduction of crude protein (CP), and reduction of ammonium-N (N [Formula: see text] -N). The response surface methodology (RSM) was used to optimize these processes. For this purpose, two sets of experiments (drying of LHM with and without SB and Ws) were designed. The independent parameters were air temperature (70, 80, and 90 °C), air velocity (1, 1.5, and 2 m s-1), layer thickness (5, 10, and 15 mm), SB (2%, 4%, and 6%), and WS (3%, 7.5%, and 12%). The results indicated that temperature and WS had the most significant influence on all responses. To maximize the dehydration rate and minimize the reduction of CP and N [Formula: see text] -N, the optimal conditions were a temperature of 78 °C, air velocity of 1 m s-1, and layer thickness of 5 mm in the first set of experiments, and a temperature of 80 °C, air velocity of 1.5 m s-1, layer thickness of 11 mm, 6% SB, and 12% WS in the second set of experiments. Under the optimum conditions, LHM treated with 6% SB and 12% WS retained 10% more CP and 58% more N [Formula: see text] -N than untreated LHM. Therefore, according to the obtained results, SB and WS are recommended as additives to reduce the CP and N [Formula: see text] -N losses of LHM during the drying process.

Refining dietary metabolisable energy and crude protein levels in relation to duck performance and behaviour.

1. The study evaluated the effect of dietary metabolisable energy (ME) content and crude protein (CP) level on the growth performance and behaviour of ducks.2. A total of 720, Cherry Valley ducks were allocated to 36 pens in groups of 20 birds. For the initial period, from 1 to 21 d age, six diets, containing a standard (SME), low (LME) and high (HME) ME of 12.14, 11.93 and 12.35 MJ/kg, and standard (SCP) or high (HCP) CP contents of 210 or 220 g/kg diet, respectively, were mixed. For the period from 22 to 42 d age, the diets contained ME of 12.98 (SME), 12.77 (LME), 13.19 (HME) MJ/kg and the levels of CP were 170 (SCP) or 180 (HCP) g/kg, respectively.3. An ME by CP interaction was seen from 1 to 21 d age in ducks fed HME + HCP diet, which had greater weight gain than those fed LME + SCP (P < 0.05). Compared to LME + SCP, dietary HME decrease feeding but increased walking behaviour compared to LME + SCP and SME + SCP (P < 0.05). High CP in LME and SME diets increased drinking behaviour (P < 0.05), but there was no change in HME diet. Compared to LME, feeding HME reduced ground pecking (P < 0.05). Feeding HME reduced feeding behaviour (P < 0.05) from 22 to 42 d age. During the same period, standing behaviour was reduced in HCP + LME (P < 0.05). Drinking was reduced in LME + SCP compared to SME + HCP and HME + HCP (P < 0.05).4. A diet formulated with HME and HCP is effective for enhancing growth performance of ducks aged 1-21 d and saving time for feeding or ground pecking, which may induce spending more time on other activities.

Adding mixed probiotic to a low-crude-protein diet: Effects on production efficiency, nutrient retention, faecal gas discharge, faecal score and meat quality of finishing pigs.

This study examined the impact of mixed probiotic inclusion in a reduced crude protein (CP) diet on production performance, nutrient retention, gas emissions, faecal score and meat quality of finishing pigs. In total, 150 pigs (body weight [BW] of 49.9 ± 2.80 kg and 6-week trial) were arbitrarily distributed to one of three dietary treatments (10 replications per treatment, five pigs including three gilts and two barrows per replication). The dietary treatments were Positive Control/standard diet, 17.5% CP (PC); Negative Control/reduced (2.5%) CP diet, 15% CP (NC); and NC + 0.1% probiotic mix (NCP). Pigs fed the NCP diet exhibited tendency to increase BW gain at Week 6, increased the average daily gain (ADG) of pigs during Weeks 3-6 and showed tendency to increase ADG during the overall period than the NC diet. The CP digestibility decreased at Week 6 and presented a tendency to decrease at Week 3 in pigs fed the NC diet compared with the PC diet. However, CP digestibility increased with the NCP diet at Weeks 3 and 6 compared with the NC diet. A tendency in the reduction of H2S emissions from pig's faeces at Weeks 3 and 6 was observed by the NCP diet compared with NC and PC diets. Pigs fed the NC diet showed a lower faecal score than the PC diet at Week 6. The NC diet resulted in lower cooking loss and drip loss to the PC diet. Moreover, longissimus muscle area showed tendency to increase, cooking loss exhibited tendency to decrease and drip loss decreased in the meat samples of pigs receiving the NCP diet compared with the NC diet alone. The NCP diet exhibited great promise in maintaining performance by enhancing the growth performance, digestibility, mitigating gas emissions and improving the quality of meat in finishing pigs.

Forage potential of several halophytic species grown on saline soil in arid environments.

This study was carried out to evaluate the forage quantity and quality of several halophyte species grown in arid-saline environments. After identifying 44 halophytic species in the region and considering the potential of quantitative and qualitative forage production, 13 species from four families, i.e. Amaranthaceae, Asteraceae, Leguminosae and Convolvulaceae, and eight genera were selected for further evaluation. These species differed significantly in terms of both forage quantity, measured in terms of fresh (FW) and dry weight (DW), and forage quality assessed in terms of tissue water content (TWC), ash, nitrogen content (N), crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), dry matter digestibility and metabolizable energy (ME). The highest fresh and dry weights were obtained from Suaeda ferticosa (1006.3 g and 306.3 g, respectively) and Noaea mucronata (909.3 g and 309 g, respectively). However, based on forage quality characteristics, Alhagi maurorum, Bassia scoparia, Noaea mucronata, Halostachys belangriana and Cressa cretica showed the best forage potential. Values of ash, CP, ADF, NDF and ME measured in the halophytes species ranged between 7.9% and 33.2%, 6.2% and 15.8%, 30.0% and 50.3%, 33.2% and 56.4%, 5.6 and 8.7 MJ kg-1, respectively. The forage quality of the evaluated halophytic plants was influenced by unfavorable environmental conditions such as high soil salinity and low rainfall, however, these species can be considered as new sources of forage. Nevertheless, further studies are needed to improve the quality of such halophytic species by reducing the ash content and increasing the ME.

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.

Multiple amino acid supplementations to reduce dietary protein for pigs during early and late finisher periods under commercial conditions.

BACKGROUND: With the easy availability and competitive prices of crystalline amino acids (AAs), the reduction of dietary crude protein (CP) for pigs during early and late finisher periods is possible under commercial conditions. Two experiments were conducted to assess the growth efficiency of early and late-finishing pigs fed with protein-restricted diets supplemented with Lys, Met, Thr, Trp, Val, Ile and His. In Experiment 1, 840 early finishing pigs were allocated to four dietary treatments with CP levels designed at 150, 142, 134, and 126 g kg-1 diet. In Experiment 2, 768 late-finishing pigs were allotted to four dietary treatments providing CP levels at 140, 130, 120, and 110 g kg-1 diet. RESULTS: In Experiment 1, the data showed that CP levels could be decreased from 150 to 126 g kg-1 without adversely affecting performance of early finishing pigs as no significant difference was observed for final bodyweight, average daily gain (ADG), feed to gain ratio (F:G), or average daily feed intake (ADFI). In Experiment 2, late-finishing pigs consuming 120 g kg-1 CP tended to have the highest ADG and lowest F:G whereas those fed the 110 g kg-1 CP diet showed the opposite trend. Based on quadratic analysis, the optimum CP levels to maximize ADG and minimize F:G were 126 and 127 g kg-1 , respectively. CONCLUSION: These findings showed that dietary CP levels could be decreased to 126 g kg-1 for early finishing pigs while improved performance was noted in late-finishing pigs consuming 120 g kg-1 CP. © 2023 Society of Chemical Industry.

Feed intake and milk yield and composition of lactating dairy goats in response to partial substitution of soybean meal for formaldehyde-treated sesame meal in the diet.

This study was conducted to evaluate the effect of substitution of soybean meal (SBM) for formaldehyde-treated sesame meal (FTSM) on nutrient intake and digestibility, ruminal and blood parameters and milk production and composition in lactating Murciano-Granadina goats. Forty lactating goats were randomly assigned to one of the following four treatments: (1) diet with 16.5% CP, containing SBM (CON); (2) diet with 16.5% CP, containing untreated SM (USM); (3) diet with 16.5% CP, containing FTSM (FT); and (4) diet with 14.5% CP containing FTSM (LPFT). The results showed that nutrient intake was highest in the FT group (p < 0.001), while it was similar between the CON and LPFT groups, except for the intake of CP, which was higher in the CON group. The FT and LPFT had lower ruminal pH compared to CON and USM groups (p < 0.001), with goats in group FT having the highest volatile fatty acids (VFA) production (p < 0.001). The highest propionate concentration was observed in the LPFT treatment (p < 0.001), followed by the FT, CON, and USM treatments. Goats offered USM and LPFT treatments presented the highest and lowest acetate: propionate values, respectively, among the experimental groups (p < 0.001). The results also showed that LPFT goats had the lowest blood urea nitrogen (BUN) level (p = 0.004), while FT goats presented a lower non-esterified FA (NEFA) level compared with CON and LPFT goats (p = 0.01). Goats offered the FT diet had the highest milk yield (p = 0.002) and energy-corrected milk yield (p < 0.001) among all dietary groups. The highest milk fat (p < 0.001), protein (p = 0.001), lactose (p = 0.007), total solids (p = 0.003), and solids-not-fat (SNF) (p = 0.003) contents were observed in FT goats, which didn't differ from USM goats. The inclusion of formaldehyde-treated SM increased the percentage of C18:3 (p < 0.001) and C20:1 (p = 0.04) FAs compared with USM and CON treatments. Milk from USM, FT, and LPFT goats had lower levels of saturated (p < 0.001) and medium-chain FAs (p = 0.014) compared with CON goats, whereas milk from CON goats had lower levels of unsaturated, monounsaturated, and long-chain FAs compared to other groups (p < 0.001). The lowest and the highest concentrations of polyunsaturated FAs were observed in CON and LPFT goats, respectively (p = 0.001). It can be concluded that SBM can be advantageously replaced by formaldehyde-treated SM in the diet as a feasible alternative to improve feed intake and production performance of dairy goats.

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

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

Assessment of dietary protein supplementation on milk productivity of commercial organic dairy farms during the grazing season.

Variability of protein and energy supply from pasture during the grazing season is a primary factor that can influence milk production of grazing organic dairy herds in the Northeast United States. This study evaluated the effects of altering the crude protein (CP) content of dietary supplements included in dairy rations fed to grazing organic dairy herds, on milk production and composition. Six commercial organic farms participated in a 6-wk trial, consisting of a 2-wk baseline period and 4-wk experimental period. Farms were paired by their summer 2017 milk urea nitrogen profile, and farms within each pair were assigned by restricted randomization to (1) continuation of their regular supplements (n = 3, control group, CON), or (2) supplement with altered CP as percentage of dry matter, formulated using an organic barley and roasted soybean mix (n = 3, treatment group, TRT). Throughout the 6-wk trial, individual milk samples were collected at 2 consecutive milkings weekly, while pasture and supplement samples, pasture measurements, and management information were collected twice weekly per farm. Data were statistically analyzed using the MIXED procedure of SAS (version 9.4, SAS Institute Inc.) for all parameters, and effects of treatment, week, and their interaction (treatment × week) were determined. The supplement CP (percentage of dry matter) during the baseline period was 13.5% for CON and 15.3% for TRT and 14.8% for CON and 19.3% for TRT during the experimental period. Milk production was 21% higher during the experimental period for TRT compared with CON (24.1 vs. 19.9 kg of milk per day, respectively). Milk production decreased for CON from wk 1 to wk 6 (23.6 vs. 20.4 kg of milk per day), whereas TRT maintained milked production from wk 1 to wk 6 (22.8 vs. 22.7 kg of milk per day). Milk composition was different between groups, with CON having higher fat percent (4.21 vs. 3.73%, respectively) and protein percent (3.15 vs. 3.05%, respectively) compared with TRT for the 6 wk. The milk urea nitrogen concentrations were similar between TRT and CON for the baseline period (11.9 vs. 12.1 mg/dL) and the final week of the experimental period (14.5 vs. 14.2 mg/dL). Although the effects of different diet CP fractions, particularly rumen undegradable protein and soluble protein, must be further delineated, these results indicate that altering the CP content of dietary supplements fed to grazing organic dairy cattle during the summer period in the Northeast US could be a useful mechanism to maintain milk production.

Production performance of Holstein cows at 4 stages of lactation fed 4 dietary crude protein concentrations.

Dairy cow responses to dietary crude protein (CP) may depend on stage of lactation. The primary objective of this study was to evaluate the effects of 4 concentrations of dietary CP on dry matter intake (DMI), production performance, net energy for lactation (NEL) output in milk, feed efficiency (FE: milk NEL/DMI), and nitrogen use efficiency (100 × milk protein-N/N intake) when fed to cows grouped as early, mid-early, mid-late, and late lactation. Our secondary objective was to determine the range of CP concentration at which production responses were not negatively affected across days in milk (DIM). Multiparous Holstein cows (n = 64) were stratified by DIM [initial average ± standard deviation: 86 ± 14.9 (early), 119 ± 10.0 (mid-early), 167 ± 22.2 (mid-late), and 239 ± 11.1 (late)] and then randomly assigned within DIM group to receive 1 of 4 total mixed rations containing 13.6, 15.2, 16.7, and 18.3% CP (dry matter basis) according to a 4 × 4 factorial arrangement of treatments. Cows were individually fed a covariate diet for 14 d, followed by 56 d of treatment diets. Milk yield and DMI were recorded daily and milk components were analyzed weekly for 2 consecutive days at 3 daily milkings. Data were analyzed using a categorical mixed-effect model to evaluate the effects of CP concentration and DIM using linear, quadratic, and cubic contrasts, and their interactions. Additionally, a mixed-effect cubic regression model was fit with DIM, dietary CP concentration, and their interaction as continuous independent variables. Dietary CP concentration deemed optimal across DIM was determined as the range of CP for which the dependent responses did not differ from the predicted maximum. With advancing stage of lactation, DMI, milk NEL output, and FE decreased linearly (from 30.4 to 28.4 kg/d for DMI, from 33.2 to 23.3 Mcal/d for NEL output, and from 1.09 to 0.82 Mcal milk NEL/kg DMI for FE for early and late lactation cows, respectively). Responses to dietary CP concentration were linear, quadratic, and cubic with the greatest values observed when cows were fed the 16.7% CP diet across DIM (30.8 kg/d, 31.0 Mcal/d, and 1.01 Mcal/kg for DMI, milk NEL output, and FE, respectively). There was an interaction between dietary CP concentration and stage of lactation for DMI, milk NEL output, milk component yield, and FE, which was due to the decline in response to additional CP as lactation progressed. Compared with the 16.7% CP diet, feeding the 18.3% CP diet decreased milk NEL 0.81 and 5.3 Mcal/d for early and late lactation cows, respectively, indicating that feeding a higher CP concentration in late lactation had a negative effect on cow performance. Nitrogen use efficiency declined linearly with increasing CP concentration and DIM. Regression analysis suggested that dietary CP ranging from 16.3 to 17.4% maintained production in early and mid-early lactation. However, dietary CP could be reduced to between 15.7 and 17.1% in late lactation. This research suggested that there are distinct ranges of dietary CP concentrations that maintain cow performance at each stage of lactation.

Effect of supplement crude protein concentration on milk production over the main grazing season and on nitrogen excretion in late-lactation grazing dairy cows.

The objectives of this study are to evaluate the effects of (1) a potential interaction between supplement crude protein (CP) concentration and differing cow genotypes on milk production, (2) differing cow genotypes on milk production, and (3) decreasing the supplement CP concentration on milk production and N excretion during the main grazing season within a spring-calving herd. A 2 × 2 factorial arrangement experiment, with 2 feeding strategies [14%; n = 30 (lower CP; LCP) and 18%; n = 28 (higher CP; HCP) CP concentrate supplements] offered at varying levels according to pasture availability and days in milk (DIM) was conducted over the main grazing season from April 3 to September 3, 2019, at University College Dublin Lyons Farm. Cows were also grouped into 2 genotype groups: lower milk genotype; n = 30 [LM; milk kg predicted transmitting ability (PTA): 45 ± 68.6 (mean ± SD); fat kg PTA: 10 ± 4.9; and protein kg PTA: 7 ± 2.3] and higher milk genotype; n = 28 [HM; milk kg PTA: 203 ± 55.0; fat kg PTA: 13 ± 3.8; and protein kg PTA: 10 ± 2.4]. A total of 46 multiparous and 12 primiparous (total; 58) Holstein Friesian dairy cows were blocked on parity and balanced on DIM, body condition score, and Economic Breeding Index. Cows were offered a basal diet of grazed perennial ryegrass pasture. The N partitioning study took place from August 25 to 30, 2019 (187 ± 15.2 DIM). No interactions were observed for any milk production or milk composition parameter. No effect of supplement CP concentration was observed for any total accumulated milk production, daily milk production, or milk composition parameter measured. The HM cows had increased daily milk yield (+1.9 kg), fat and protein (+0.15 kg), and energy-corrected milk (+1.7 kg), compared with the LM cows. Furthermore, HM cows had decreased milk protein concentration (-0.1%) compared with LM cows. For the N partitioning study, cows offered LCP had increased pasture dry matter intake (PDMI; +0.9 kg/d), dietary N intake (+0.022 kg/d), feces N excretion (+0.016 kg/d), and decreased N partitioning to milk (-2%), and N utilization efficiency (-2.3%). In conclusion, offering cows LCP had no negative influence on milk production or milk composition over the main grazing season where high pasture quality was maintained. However, any potential negative effects of offering LCP on milk production may have been offset by the increased PDMI. Furthermore, offering cows LCP decreased N utilization efficiency due to the higher PDMI and feed N intake associated with cows on this treatment in our study.

Effects of dietary butyrate supplementation and oral nonsteroidal anti-inflammatory drug administration on serum inflammatory markers and productivity of dairy cows during the calving transition.

Dairy cattle experience inflammation during the calving transition period, and butyrate and nonsteroidal anti-inflammatory drugs (NSAID) are expected to reduce the inflammation. Our objective was to evaluate the effects of dietary butyrate supplementation and oral NSAID administration on feed intake, serum inflammatory markers, plasma metabolites, and milk production of dairy cows during the calving transition period. Eighty-three Holstein cows were used in the experiment with a 2 × 2 factorial arrangement of treatments. The cows were blocked by parity and calving date, and randomly assigned to a dietary butyrate or control supplement, and NSAID or a placebo oral administration. Experimental diets were iso-energetic containing calcium butyrate at 1.42% of diet dry matter (DM) or the control supplement (1.04% commercial fat supplement and 0.38% calcium carbonate of diet DM). The close-up diets contained 13.3% starch and 42.4% neutral detergent fiber on a DM basis, and were fed from 28 d before expected calving date until calving. The postpartum diets contained 22.1% starch and 34.1% neutral detergent fiber on a DM basis and were fed from calving to 24 d after calving. Oral NSAID (1 mg of meloxicam/kg of body weight) or placebo (food dye) was administered 12 to 24 h after calving. Dietary butyrate supplementation and oral NSAID administration did not affect milk yield or postpartum serum concentrations of amyloid A and haptoglobin. However, butyrate-fed cows increased plasma fatty acid concentration on d -4 relative to calving (501 vs. 340 µEq/L) and tended to increase serum haptoglobin concentration (0.23 vs. 0.10 mg/mL). There was a supplement by drug interaction effect on plasma glucose concentration on d 4; in cows administered the placebo drug, butyrate supplementation decreased plasma glucose concentration compared with control-fed cows (62.8 vs. 70.1 mg/dL). Butyrate-fed cows tended to have lower milk crude protein yield compared with cows fed the control diet (1.21 vs. 1.27 kg/d). Dietary butyrate supplementation and oral NSAID administration did not have overall positive effects on production performance of dairy cows during the calving transition period.

In situ ruminal disappearance of crude protein and phytate from differently processed rapeseed meals in dairy cows.

BACKGROUND: The influence of different processing conditions of rapeseed meal on ruminal degradation of crude protein and phytate in dairy cows was investigated. Following oil extraction from the rapeseed, five residence times in the desolventizer/toaster were chosen to remove the solvent from the meal. Rapeseed cake and rapeseed meals were incubated in situ in the rumen of three fistulated dairy cows to determine ruminal degradation parameters. RESULTS: With increasing residence time in the desolventizer/toaster the ruminal degradation of crude protein decreased significantly for every treatment step. Ruminal phytate degradation and crude protein degradation were affected almost identically. CONCLUSION: The processing conditions of rapeseed meal have a major impact on the ruminal degradation of crude protein and phytate, indicating a potential conflict of interest regarding the production process. Large amounts of undegradable rumen protein are often intended for high-yielding dairy cows whereas a high level of ruminal degradation is preferred for phytate to increase absorption of phosphorus in the small intestine. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Control measures for airborne ammonia and respirable dust exposure in swine barns.

Extended exposure to airborne contaminants such as ammonia (NH3) and respirable dust in swine facilities has been associated with various health problems among swine barn workers. The overall goal of this study was to assess the impact of selected control measures, namely, canola oil sprinkling, low crude protein diet, high level of cleaning, and manure pH manipulation, on NH3 and respirable dust concentrations in swine production rooms through area sampling and on worker exposure to these contaminants in accordance with National Institute of Occupational Safety and Health (NIOSH) methods for occupational exposure monitoring. Results from five trials showed that low crude protein diet can be used for reducing worker exposure to NH3 while oil sprinkling can be used for controlling respirable dust levels in swine rooms. Reduction in airborne levels did not translate to reduction in occupational exposure. Commercial NH3 monitors showed higher readings than the standard NIOSH 6015 method.

Feeding behavior of post-weaned crossbred steers supplemented in the dry season of the year.

The objective of this study was to evaluate the feeding behavior of grazing steers supplemented in the dry season of the year. Thirty-two castrated crossbred (½ Holstein-Zebu) steers with an average initial weight of 378 ± 7.54 kg, aged 14 months, were distributed into four treatment groups in a completely randomized design with eight replicates. The animals were managed in an area covered with a pasture of Brachiaria brizantha cv. Marandu, in a rotational grazing system. The supplement was formulated so that the animals in the different treatment groups would ingest the same amount of crude protein (CP) daily. Thus, the treatments consisted of increasing levels of supplementation, based on the animals' body weight (BW), as the protein content of the supplement was reduced. The following treatments (dry matter basis) were tested: T2, supplement at 0.2% BW, with 50% CP; T4, supplement at 0.4% BW, with 25% CP; T6, supplement at 0.6% BW, with 16.67% CP; and T8, supplement at 0.8% BW, with 12.5% CP. Forage dry matter intake decreased linearly (P < 0.05), characterizing a substitution effect. The increasing supplementation levels influenced the animals' feeding behavior, especially grazing time, total feeding time, number of grazing bouts, and number of bites per day, which showed a positive quadratic response (P < 0.05), and rumination time, number of rumination bouts, number of cuds ruminated per day, and number of chews per ruminated cud, which exhibited a negative quadratic behavior (P < 0.05). Dry matter and neutral detergent fiber (NDF) feed efficiencies and dry matter and NDF rumination efficiencies responded quadratically (P < 0.05). In conclusion, concentrate supplementation at up to 0.8% BW improves the feeding behavior of grazing steers in terms of the intake of concentrate supplement and forage as well as the feed and rumination efficiencies.

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

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

Effect of increasing dietary protein with constant lysine:methionine ratio on production and omasal flow of nonammonia nitrogen in lactating dairy cows.

Eight lactating cows were fed 4 diets in which dietary crude protein (CP) was increased in steps of approximately 2 percentage units from 11 to 17% of DM by replacing high-moisture corn with soybean meal supplemented with rumen-protected Met to maintain a Lys:Met ratio of 3:1 in metabolizable protein. Trial design was a replicated 4 × 4 Latin square; experimental periods lasted 28 d, with data and sample collection being performed during wk 3 and 4 of each period. Digesta samples were collected from the rumen as well as the omasum to measure metabolite concentrations and ruminal outflow of N fractions using infusion of 15N-enriched ammonia to quantify microbial nonammonia N (NAN) and nonmicrobial NAN. Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc.). There were linear increases in the yields of milk and true protein and concentration of milk urea N, and a linear decrease in N efficiency, with increasing dietary CP. Apparent ruminal and total-tract N digestibility increased linearly with increasing dietary CP, but estimated true total-tract N digestibility was not affected. Apparent digestibility of the other macronutrients was not influenced by diet. Ruminal ammonia, total AA and peptides, and branched-chain VFA also increased linearly with dietary CP. The 15N enrichment of liquid- and particle-associated microbes linearly declined with increasing dietary CP due to decreasing 15N enrichment of the ammonia pool. Although no effect of dietary CP on nonmicrobial NAN flow was detected, total NAN flow increased linearly from 525 g/d at 11% CP to 637 g/d at 17% CP due to the linear increase in microbial NAN flow from 406 g/d at 11% CP to 482 g/d at 17% CP. Under the conditions of this study, when dietary CP was increased by adding soybean meal supplemented with rumen-protected Met, improved milk and protein yields were driven not by RUP supply but by increased ruminal outflow of microbial protein.

In situ and in vitro determination of the protein value of feeds for ruminants.

The objective of this study was to estimate the amount of post-rumen crude protein (prCP), a precursor to metabolisable protein for ruminants, of feeds and feed mixtures using an in situ and in vitro method, and to contrast the results of both approaches. For this, 34 samples were examined: 9 feeds, 13 feed mixtures made thereof and 12 feed mixtures provided by commercial dairy farms. As a minor aspect, additivity of protein values from feeds was evaluated by comparing measured and calculated values of feed mixtures. Effective prCP was calculated for assumed rumen passage rates (k) of 0.05 h-1 (prCP5) and 0.08 h-1 (prCP8) by in situ measurements of rumen undegraded CP and fermented organic matter (FOM) assuming an efficiency of 181 g microbial CP/kg FOM. Additionally, effective prCP in vitro was estimated using the modified Hohenheim gas test (modHGT) through incubation in rumen-fluid buffer solution for 8 and 24 h followed by ammonia distillation. In vitro estimations were highly correlated with in situ values for both passage rates (k = 0.05 h-1: p < 0.001, R2 = 0.68; k = 0.08 h-1: p < 0.001, R2 = 0.76). The in vitro method yielded higher values for effective prCP than the in situ approach with 29 g/kg OM (k = 0.05 h-1) and 37 g/kg OM (k = 0.08 h-1) on average for all samples. Small positive associative effects - reflecting non-additivity - were found, averaging at 2.2 g prCP8/kg OM (p < 0.05) for the in situ and 10.7 g prCP8/kg OM (p < 0.001) for the in vitro approach. Due to the need of an assumption of a certain value for microbial efficiency in situ, effective prCP might be more accurately estimated in vitro, accounting for nutrient-specific efficiencies as well as interactions between carbohydrate and protein degradation by rumen microbes. Furthermore, the modHGT highlighted associative effects more pronounced and seems suitable as a routine method due to the comparably low effort and high sample throughput. The potential of the modHGT to determine the protein value of feeds could be demonstrated by our study.