High RUP Research Articles

PSIX-22 Performance, Digestibility, and Blood Parameters in Pregnant Beef Cows Fed Total Mixed Ration Silages

Abstract The aim of this study was to investigate the effects of two total mixed ration (TMR) silages (low and high rumen undegradable protein; RUP) on digestibility, blood parameters, and performance in pregnant beef cows. Thirty-three mid-gestation (~130 d of gestation) Tabapua beef cows were randomly assigned to 1 of 2 treatments: 1) a TMR silage containing Brachiaria grass, soybean hulls, urea, and mineral mix (low RUP; n = 16) or 2) a TMR silage containing Brachiaria grass, DDG, and mineral mix (high RUP; n = 17). The concentration of A1 fraction was, on average, 12.9% and 34.0% of N in low and high RUP silages, respectively. A preservative with a blend of organic acids, surfactants, and activated propionates was applied in both silages. Pressed bag silos were used to conserve silages for 7 wk. Cows were housed in individual pens for 100 d. During a 4-d digestion period (at 50 d of housing), fecal samples were collected for measurement of nutrient digestibility using undigested neutral detergent fiber as a marker. Blood parameters were collected at the last day of housing. Statistical analysis of experimental data was performed using the GLM procedure of SAS 9.4. Diet, calf sex (male or female), and interactions between these factors were considered fixed effects. No differences were obtained for initial BW. High RUP diet showed greater final BW (P = 0.0004) and ADG (P = 0.0003). Cows fed high RUP gained 50 g/d, while cows fed low RUP diet lost 445 g/d. Dry matter intake was greater by 23% (P < 0.0001) in cows consuming high RUP silage. Dry matter, CP, and NDF digestibility did not differ between treatments. Regarding blood parameters, no differences were observed for glucose at 0 h and 4 h post-feeding. Plasma urea at 0 h post-feeding was greater in cows fed low RUP silage (P = 0.0003). However, no differences were observed for plasma urea at 4 h post-feeding. The plasma concentrations of non-esterified fatty acids (P = 0.017) and beta-hydroxy-butyric acid (P = 0.002) were greater in cows consuming low RUP diet. Overall, feeding pregnant cows during mid-gestation with TMR silage containing high RUP promotes greater performance.

Effects of dietary protein concentration and degradability on performance, carcass characteristics, net energy utilization, and metabolizable protein balance of finishing beef heifers receiving 0 or 400 mg of ractopamine hydrochloride

This study evaluated the effects of feeding beef cattle finishing diets with greater than 14.0% dietary CP and with or without ractopamine hydrochloride (RH) on growth performance, carcass merit, net energy utilization, and metabolizable protein balance. Heifers (n = 525) were assigned to 48 pens in a generalized complete block design, and pens of cattle were assigned randomly to 0 or 400 mg of RH/animal per day and 3 CP treatments in a 2 × 3 factorial arrangement (n = 8 pens/treatment) fed for 35 d before slaughter. Dietary protein treatments were steamflaked corn-based diets containing 13.9% CP, 8.9% RDP, and 5.1% RUP (CON); 20.9% CP, 14.4% RDP, and 6.5% RUP (High RDP); or 20.9% CP, 9.7% RDP, and 11.2% RUP (High RUP) on a DM basis. No RH × CP interactions were observed. Final BW, ADG, water disappearance, DMI, and G:F were not different among CP treatments. Dressing percentage was greater for cattle fed High RDP than for those fed High RUP, but other carcass outcomes did not differ. The MP balance was greatest for High RUP, intermediate for High RDP, and least for CON. Cattle receiving 400 mg of RH had greater final BW, ADG, G:F, and hot carcass weight. The LM area was greater and KPH was less for 400 versus 0 mg of RH. Carcass-adjusted final BW, ADG, and G:F were greater for cattle consuming 400 mg of RH. Cattle fed 400 mg of RH had greater performance-adjusted and observed:expected NEm and NEg. The MP balance was less for 400 versus 0 mg of RH. Dietary CP requirements were greater for cattle fed 400 compared with 0 mg of RH but did not exceed the CP supplied by CON, High RDP, or High RUP. Feeding greater than 14.0% CP does not negatively affect performance or carcass characteristics of finishing cattle, and the absence of interactions between CP and RH suggests that RH does not increase CP requirements above those provided in a typical finishing cattle diet.

Supplementation of n-3 fatty acid and ruminal undegradable to degradable protein ratio in young lambs raised under heat condition: effects on growth performance and urinary purine derivatives.

The present study evaluated the effect of supplementation alpha-linolenic fatty acid source (ALA) with different rumen undegradable to degradable protein ratios [low ratio (LR) = 26:74; high ratio (HR) = 36:64 based on CP%] on growth performance, nutrient digestibility, fecal score, animal feeding behavior, and urinary purine derivatives (PD) in young lambs during hot season. Forty 10-day-old lambs (averaging body weight of 7.9 ± 0.8kg) were used in a completely randomized block design with a 2 × 2 factorial arrangement as following treatments (10 lambs/treatment): (1) no n-3 FA supplementation with LR diet (NALA-LR), (2) no ALA supplementation with HR diet (NALA-HR), (3) supplementation of ALA with LR diet (ALA-LR), and (4) supplementation of ALA with HR diet (ALA-HR). Results showed that ALA supplementation slightly increased feed efficiency (FE; tendency, P = 0.076), improved fecal score (P = 0.045), and reduced rectal temperature (tendency, P = 0.064) during pre-weaning period. The HR diets improved average daily gain (ADG; P < 0.01), wither height (post-weaning; P = 0.015), and final BW (P = 0.048) compared with LR diets. The greatest ADG (pre-weaning; P = 0.012), structural growth, and the lowest urinary nitrogen exertion (P = 0.043) were found in the ALA-HR treatment. No change was found for ruminal fermentation, nutrient digestibility, and animal behavior in lambs fed different experimental treatments. In summary, results indicated that concurrent feeding of ALA and high dietary RUP:RDP ratio can be recommendable that is likely due to more efficient nitrogen utilization when young lambs are raised during hot season. HIGHLIGHTS: • The interaction of n-3 FA and nitrogen was evaluated in pre-weaning lambs raised under heat condition. • Supplementation of n-3 FA increased FE and improved fecal score in heat-exposed lambs during pre-weaning period. • The high RUP:RDP ratio improved skeletal growth during post-weaning period. • Concurrent feeding of n-3 FA and high dietary RUP:RDP ratio is recommendable in young lambs raised during hot season.

Forage source (alfalfa hay vs wheat straw) and rumen undegradable to degradable protein ratio: Effects on growth performance, microbial protein yield, digestibility, blood metabolites, and behavior of Holstein dairy calves

Aim of the study: The effects of forage source (alfalfa hay; AH vs. wheat straw; WS) with rumen undegradable to degradable protein ratio [low ratio (LR) = 28:72; high ratio (HR) = 36:64] were evaluated in young dairy calves.Area of study: Arak, Iran.Material and methods: Forty-eight 3-d old female Holstein dairy calves (44.5 kg of BW) were allocated in four treatments: (1) AH with low dietary RUP:RDP ratio (AH-LR); (2) AH with high dietary RUP:RDP ratio (AH-HR); (3) WS with low dietary RUP:RDP ratio (WS-LR); and (4) WS with high dietary RUP:RDP ratio (WS-HR), being RDP and RUP rumen degradable and undegradable proteins, respectively. The calves weaned on d 53 of the experiment and remained in the study until d 73 of age.Main results: The average daily gain and feed efficiency were improved in dairy calves receiving HR diets compared to LR diets during the post-weaning period (p&lt;0.05). The fecal score (p=0.03) and neutral detergent fiber digestibility (p=0.04) were improved when calves fed WS diets compared to AH diets. Feeding HR diets increased allantoin (p=0.04) and microbial protein yield, and reduced blood urea nitrogen concentration (p=0.03) compared to LR diets. Assessing the interaction effects of the experimental factors resulted that the greatest BW, wither height, and blood beta-hydroxybutyrate, and the lowest urinary N concentration were observed in the WS-HR treatment (p&lt;0.05).Research highlights: Feeding WS with high RUP:RDP ratio is recommendable in dairy calves due to the improvement in gain and N efficiency.

Effects of protein content and rumen-undegradable to rumen-degradable protein ratio in finely ground calf starters on growth performance, ruminal and blood parameters, and urinary purine derivatives

This study investigated the effects of feeding finely ground starter diets containing either 18 or 22% crude protein (CP) content [dry matter (DM) basis] and high or low ratios of rumen-undegradable protein to rumen-degradable protein (RUP:RDP) on growth performance, nutrient digestibility, ruminal fermentation, blood metabolites, and urinary purine derivatives in dairy calves. A total of 48 three-day-old female Holstein dairy calves with 40.2 ± 2.5 kg of initial body weight (BW) were randomly assigned in a complete randomized block design to a 2 × 2 factorial arrangement of treatments (12 calves/treatment). Treatments were as follows: (1) finely ground starter diet (mean particle size = 0.69 mm) with 18% CP and low RUP:RDP ratio [low ratio (LR) = 26:74; 18CP-LR]; (2) finely ground starter diet with 18% CP and high RUP:RDP ratio [high ratio (HR) = 35:65; 18CP-HR]; (3) finely ground starter diet with 22% CP and low RUP:RDP ratio (22CP-LR); (4) finely ground starter diet with 22% CP and high RUP:RDP ratio (22CP-HR) on DM bases. Blocking was based on the day of treatment assignment, and treatments were randomly assigned within each block. Calves received 4 L of milk daily from d 3 to 10, 7 L/d from d 11 to 40, 4 L/d from d 41 to 49, and 2.5 L/d from d 50 to 53, and then all calves were weaned but remained in the experiment until d 83 of age. The results showed that overall average daily gain (ADG), weaning BW, and feed efficiency (FE) were greater in 22% CP treatments than in 18% CP. Increasing the starter CP content from 18 to 22% of DM did not influence overall starter feed intake, milk intake, total dry matter intake (DMI), postweaning ADG, and FE of calves. No effect of RUP:RDP ratio was observed for starter feed intake, milk intake, total DMI, preweaning ADG, FE, and grams of CP per megacalorie of metabolizable energy. The RUP intake and postweaning ADG were greater for calves fed the HR diets than for those fed the LR diets. The digestibility of neutral detergent fiber was greater, and the digestibility of OM tended to be greater, and the ruminal concentrations of total short-chain fatty acids (SCFA), acetate proportion, and acetate-to-propionate ratio were greater in 22% CP than in 18% CP. A 2-way interaction between starter protein content and time was observed for total ruminal SCFA, acetate proportion, and acetate-to-propionate ratio, indicating that starter CP concentration had more effect on ruminal parameters. Preweaning urinary purine derivatives, preweaning microbial protein synthesis, and postweaning urinary nitrogen were greater for calves fed the 22CP diets than for those fed the 18CP diets but were not affected by the different RUP:RDP ratios. The concentrations of blood glucose and insulin were greater in 22% CP than in 18% CP diets. The blood insulin concentration was greater when calves received the HR diets compared with the LR diets. Therefore, we conclude that greater starter protein content can have beneficial effects on growth performance, probably through increased microbial protein synthesized and preweaning blood insulin concentration; however, a greater RUP:RDP ratio showed marginal effects on growth performance during the postweaning period.

Effects of inclusion different level of low-quality forage and ruminal undegradable protein to degradable protein ratio in starter diet on growth performance, ruminal fermentation, and urinary purine derivatives in young lambs

Forty 12-day-old lambs with an average BW of 6.37 kg were allocated in a completely randomized design with a 2 × 2 factorial arrangement to evaluate the effects of wheat straw feeding level (WS; 10% vs. 25%, DM basis) and rumen undegradable to degradable protein ratio [RUP:RDP; low ratio (LR) = 27:73; high ratio (HR) = 38:62] on growth performance, nutrient digestibility, ruminal fermentation, microbial protein yield (MPY), blood metabolites, and liver enzymes. Treatments (10 lambs/each; 5 males and 5 females) were: (1) 10% WS with low RUP:RDP ratio (10WS-LR); (2) 10% WS with high RUP:RDP ratio (10WS-HR); (3) 25% WS with low RUP:RDP ratio (25WS-LR); and (4) 25% WS with high RUP:RDP ratio (25WS-HR). Lambs were weaned on d 82 of the experiment and remained in the study until d 92. Lambs had free access to starter diet throughout the experiment. Results show that starter intake, average daily gain, and feed efficiency did not change among experimental treatments. Organic matter digestibility was reduced in 25WS diets. Greater organic matter digestibility, fibre digestibility (tendency; p = 0.064), wither height (d 82), and urinary allantoin was found in HR compared to LR diets. However, ruminal NH3-N concentration and urinary nitrogen excretion was greater in LR diets indicating lower nitrogen utilization efficiency. The greatest ruminal butyrate concentration as well as the greatest concentration of blood beta-hydroxybutyrate was found for 25WS-HR diet at d 90 of experiment. The blood urea concentration was reduced in HR diets compared to LR diets. In summary, high RUP:RDP ratio is advisable when young lambs received high level of WS in starter diet due to improve nutrient digestibility and nitrogen efficiency.

Effects of different rumen undegradable to rumen degradable protein ratios on performance, ruminal fermentation, urinary purine derivatives, and carcass characteristics of growing lambs fed a high wheat straw-based diet

Abstract The present study aimed to evaluate the effects of various rumen undegradable to rumen degradable protein ratios (RUP:RDP) on the performance, rumen fermentation pattern, urinary purine derivatives, and carcass characteristics in growing lambs when received a high dietary wheat straw level (420 g/kg, DM basis). Lambs (average initial live weight = 27.2 ± 2.4 kg) were individual housed (n = 18, 6 animals/treatment) to evaluate the effects of treatments. The RUP:RDP ratios tested were obtained through replacing extruded soybean meal (ESBM; RUP = 64 %, based on total CP) instead of conventional soybean meal (CSBM; RUP = 26 %, based on total CP) in proportion of 0, 50, and 100 % in order to obtain ratios of (1) low RUP:RDP ratio as LR diet (25:75); (2) moderate RUP:RDP ratio as MR diet (30:70) (3) high RUP:RDP ratio as HR diet (35:65). The study lasted 10 weeks. Dry matter intake did not differ among experimental treatments (P = 0.80), while average daily gain (ADG) and final BW were linearly improved (P

Effects of corn grain processing method (ground versus steam-flaked) with rumen undegradable to degradable protein ratio on growth performance, ruminal fermentation, and microbial protein yield in Holstein dairy calves

The hypothesis of the current study was that steam-flaking corn grain will increase ruminal available starch, but reduce undegradable protein reaching the small intestine and hence formulating the starter diet with higher undegradable protein content may influence dairy calf performance. The effects of corn processing method (ground corn grain; GC vs. steam-flaked corn grain; SFC) with rumen undegradable to degradable protein ratios [low ratio (LR) = 28:72; high ratio (HR) = 37:63 based on %CP] on growth performance, feeding behavior, nutrients digestibility, ruminal fermentation, urinary purine derivatives and blood metabolites of Holstein dairy calves were evaluated. Forty-eight 3-day-old calves (24 females and 24 males) with a starting BW of 39.5 kg were used in a completely randomized block design with a 2 × 2 factorial arrangement of treatments. Experimental treatments were: (1) ground corn with low RUP:RDP (GC-LR); (2) ground grain with high RUP:RDP (GC-HR); (3) steam-flaked corn with low RUP:RDP (SFC-LR); and (4) steam-flaked corn with high RUP:RDP (SFC-HR). All calves were weaned on d 63 of age and, remained in the study until d 83 to take final measurements. Starter intake was not influenced by the grain processing method nor by dietary RUP:RDP ratio; however, the average daily gain and feed efficiency were improved and final body weight was higher in SFC fed calves. Feeding SFC diet improved the faecal score, increased the time spent on eating and slightly increased ruminating time. The LR diet improved neutral detergent fiber digestibility. Greater ruminal concentrations for total short-chain fatty acids, propionate, and butyrate were obtained when calves fed on SFC diet in pre-weaning period. The greatest heights for both wither and hip among experimental treatments were obtained in SFC-HR treatment. The higher urinary allantoin excretion and microbial protein yield, and lower urinary nitrogen excretion on the other hand, reflected an improved nitrogen efficiency in the SFC diet compared to the GC diet. Blood concentrations for glucose, beta-hydroxybutyrate and insulin were higher, and blood urea nitrogen concentration was lower in calves fed on SFC diet. In conclusion, considering our experimental condition, feeding steam-flaked corn in starter diet of dairy calves is favourable compared to ground corn grain, but RUP:RDP ratio did not influence animal performance per se. Skeletal growth was improved when SFC was fed with greater RUP:RDP ratio in starter diet which may be recommendable in replacement heifer rearing programs.

Precision-feeding dairy heifers a high rumen-undegradable protein diet with different proportions of dietary fiber and forage-to-concentrate ratios.

The addition of dietary fiber can alter nutrient and N utilization in precision-fed dairy heifers and may further benefit from higher inclusion levels of RUP. The objective of this experiment was to determine the effects of feeding a high-RUP diet when dietary fiber content was manipulated within differing forage-to-concentrate ratios (F:C) on nutrient utilization of precision-fed dairy heifers. Six rumen-cannulated Holstein heifers (555.4 ± 31.4 kg BW; 17.4 ± 0.1 mo) were randomly assigned to 2 levels of forage, high forage (HF; 60% forage) or low forage (LF; 45% forage), and to a fiber proportion sequence (low fiber: 100% oat hay and silage [OA], 0% wheat straw [WS]; medium fiber: 83.4% OA, 16.6% WS; and high fiber: 66.7% OA, 33.3% WS) administered according to a split-plot 3 × 3 Latin square design (21-d periods). Similar levels of N intake (1.70 g N/kg BW) and RUP (55% of CP) were provided. Data were analyzed as a split-plot, 3 × 3 Latin square design using a mixed model with fixed effects of period and treatment. A repeated measures model was used with data that had multiple measurements over time. No differences were observed for DM, OM, NDF, or ADF apparent digestibility coefficients (dC) between HF- and LF-fed heifers. Heifers receiving LF diets had greater starch dC compared to HF heifers. Increasing the fiber level through WS addition resulted in a linear reduction of OM dC. There was a linear interaction for DM dC with a concurrent linear interaction in NDF dC. Nitrogen intake, dC, and retention did not differ; however, urine and total N excretion increased linearly with added fiber. Predicted microbial CP flow (MP) linearly decreased with WS inclusion mainly in LF heifers, as indicated by a significant interaction between F:C and WS. Rumen pH linearly increased with WS addition, although no F:C effect was detected. Ruminal ammonia concentration had an opposite linear effect with respect to MP as WS increased. Diets with the higher proportion of fiber benefited the most from a high RUP supply, complementing the substantial reduction in predicted MP caused by the incremental dietary fiber concentration. These results suggest that RUP supplementation is a practical method for reestablishing optimal ruminal N balance in the event of increased dietary fiber through forage inclusion in precision-fed dairy heifer diets.

THE EFFECT OF RUMEN UNDEGRADABLE PROTEIN LEVEL OF CONCENTRATE WITH RICE STRAW AS BASAL DIET ON GROWTH PERFORMANCE OF SUMBA ONGOLE BEEF CATTLE

This research was conducted to determine growth performance of SO beef catlle fed rice straw added with concentrate with different levels of RUP, RUP used was soybean meal protected with 0.8% formaldehyde. Thirty six SO bull were divided into two groups at random, group that fed low and high RUP. Feed in the form of rice straw and concentrate with a ratio of 30:70 in dry matter (DM). Cattle fed low RUP get concentrate containing DM 91.22%, crude protein (CP) 19.38%, RUP 33.05%, and TDN 51.71%, whereas cattle fed high RUP get a concentrate with DM 91.13%, CP 19.40%, RUP 41.13%, and TDN 51.57%. Water was given unlimited. The nutrient intake and growth performance parameters analyzed using independent sample t-test, average daily gain was analyzed by ANCOVA with initial body weight as covariates. Intake RDP and RUP had significant effect (P&lt;0.05) between cattle fed low and high RUP. Nutrient intake (DM, CP, TDN) and growth performance (average daily gain (ADG), feed conversion, feed cost per gain) showed not significant between cattle fed low and high RUP. The conclusion were the increased of RUP levels could improved growth performance of SO beff cattle.

Interactions between levels of heat-treated soybean meal and prilled fat on growth, rumen fermentation, and blood metabolites of Holstein calves.

This study evaluated the interaction of RUP and fat levels on growth, rumen fermentation, and blood metabolites of Holstein calves. Forty 3-d-old calves (20 females and 20 males) with a starting BW of 40.6 ± 2.8 kg were used in a completely randomized design with a 2 × 2 factorial arrangement of treatments. Within sex treatments were: (1) high RUP and low fat (HRUP-LF); (2) low RUP and high fat (LRUP-HF); (3) high RUP and low fat (HRUP-LF); and high RUP and high fat (HRUP-HF). Low-RUP starter contained 21.5%, whereas high RUP starter contained 34.3% RUP as % of CP, whereas low fat starter contained 2.9% and high starter contained 5.8% crude fat based on DM. Isonitrogenous levels in the starter grain were maintained by replacing solvent soybean meal with heat treated soybean meal while fat levels were increased by the addition of prilled fatty acids. Calves were housed individually and had ad libitum access to water and calf starter throughout the study. All calves were weaned on d 60 of age but remained in the study until d 70 for final measurements. Overall, there was no interaction between RUP and fat levels for measured variables. Starter intake tended ( = 0.09) to be greater for calves fed low fat starter during the postweaning period, although over the whole experiment and during the preweaning period, differences in starter intake were not different. Although there were no differences for most VFA concentrations, the molar proportion of butyrate tended ( < 0.08) to be greater in the rumen of calves fed low-fat starter compared to those fed high-fat starter. Serum total protein was lower ( < 0.05) and serum cholesterol was greater ( < 0.01) for calves fed high-fat starter by d 65 of life. The concentration of alanine aminotransferase was also lower ( < 0.05) for calves fed high-fat starter compared to those fed low-fat starter on d 65, and these levels tended to increase with the addition of RUP ( < 0.07). In conclusion, no effects were attributable to feeding a high-RUP starter. However, feeding a calf starter with over 3% fat appeared to decrease starter intake as growth progressed.

Nutrient content of brewers grains produced at a commercial brewery: Variation in protein/nitrogen, fiber, carbohydrate, fat, and minerals

<h2>ABSTRACT</h2> This study analyzed wet brewers grain samples taken from a large commercial brewery. Samples (n=48) taken over a 1-yr period averaged 33.1% CP (previous reports indicated CP% near or less than 30%). Low lysine concentrations and high RUP concentrations indicate a need for proper RUP and amino acid (AA) formulation. Samples were also divided and composited into low- and high-CP groups; every 3 samples, starting from the least to the greatest CP, were composited to produce 16 samples representative of the range in CP. These samples were analyzed for DM, CP, ammonia N, and AA concentration. The 8 lowest CP composites averaged 32.2% CP and the 8 highest averaged 34.0% CP. A difference was observed in AA concentrations (analyzed from borate-phosphate buffer residues, which contain insoluble true protein and are useful in determining RUP) between the 2 groups (P<0.05), but AA profiles were consistent between the 2 CP composite groups. Fiber (NDF) fractions were analyzed both with and without added sulfite. This yielded different results between methods, as samples without added sulfite yielded NDF values greater than current published values; hence, the use of sulfite is recommended for NDF analysis. Fat, starch, sugar, and mineral concentrations were within ranges already published.

The effect of lung stretch during sleep on airway mechanics in overweight and obese asthma

Both obesity and sleep reduce lung volume and limit deep breaths, possibly contributing to asthma. We hypothesize that increasing lung volume dynamically during sleep would reduce airway resistance in asthma. Asthma (n=10) and control (n=10) subjects were studied during sleep at baseline and with increased lung volume via bi-level positive airway pressure (BPAP). Using forced oscillations, respiratory system resistance (Rrs) and reactance (Xrs) were measured during sleep and Rrs was partitioned to upper and lower airway resistance (Rup, Rlow) using an epiglottic pressure catheter. Rrs and Rup increased with sleep (p<0.01) and Xrs was decreased in REM (p=0.02) as compared to wake. Rrs, Rup, and Rlow, were larger (p<0.01) and Xrs was decreased (p<0.02) in asthma. On BPAP, Rrs and Rup were decreased (p<0.001) and Xrs increased (p<0.01), but Rlow was unchanged. High Rup was observed in asthma, which reduced with BPAP. We conclude that the upper airway is a major component of Rrs and larger lung volume changes may be required to alter Rlow.

Effects of ruminal protein degradability and frequency of supplementation on site and extent of digestion and ruminal fermentation characteristics in lambs fed low-quality forage1

Four ruminally and duodenally cannulated Suffolk wether lambs (34.5 +/- 2.0 kg initial BW) were used in a 4 x 4 Latin square-designed experiment to examine the effects of ruminal protein degradability and supplementation frequency on site and extent of digestion in lambs consuming a low-quality forage diet. Wethers were fed a basal diet of mature crested wheatgrass hay (4.2% CP) for ad libitum consumption plus 1 of 4 supplements: 1) a high RDP supplement provided daily (RDP-D), 2) the high RDP supplement provided on alternate days (RDP-A), 3) a high RUP supplement provided on alternate days (RUP-A), or 4) a 50:50 mixture of the RDP and RUP supplements, provided on alternate days (MIX-A). Forage OM, N, NDF, or ADF intakes were not affected by treatment. True ruminal OM digestibility was greater (P < 0.001) for MIX-A lambs compared with other treatments. True ruminal N digestibility was less (P < 0.01) in RUP-A lambs compared with other treatments. Ruminal digestibilities of NDF and ADF were greater (P <or= 0.01) for MIX-A lambs compared with other treatments. There was a treatment x hour interaction (P < 0.001) with a delay in peak concentrations within the RDP-A lambs. However, lambs supplemented with RUP had less (P < 0.001) ruminal ammonia concentrations compared with RDP-D lambs, with RUP-A lambs exhibiting the least concentrations and least variation over time. Ruminal urease activity was not affected by treatment. Microbial N flow was not affected by treatment; however, there was an increase (P = 0.004) in microbial efficiency for RDP-D lambs. Alternate day protein supplementation with a mixture of RDP and RUP may improve digestibility in lambs consuming low-quality forage, which may be related to decreased fluctuation in ruminal ammonia concentrations as a result of greater endogenous N recycling.

Effects of ruminal protein degradability and frequency of supplementation on nitrogen retention, apparent digestibility, and nutrient flux across visceral tissues in lambs fed low-quality forage1

Two experiments were conducted to determine the effect of ruminal protein degradability and supplementation frequency on intake, apparent digestibility, N retention, and nutrient flux across visceral tissues of lambs fed a low-quality forage diet. In both experiments, wethers were fed a basal diet of mature crested wheatgrass hay (4.2% CP) for ad libitum consumption plus 1 of 4 supplements: 1) a high RDP supplement provided daily (RDP-D), 2) the high RDP supplement provided on alternate days (RDP-A), 3) a high RUP provided on alternate days (RUP-A), or 4) a 50:50 mixture of the RDP and RUP supplements provided on alternate days. In Exp. 1, 12 lambs (29.9 +/- 2.7 kg initial BW) were used. Forage OM, NDF, and ADF intake were not affected by treatment. Total tract digestibilities (OM, NDF, ADF, and N) were unaffected (P >or= 0.15) by treatment. Neither protein degradability nor supplementation frequency had an effect (P >or= 0.52) on N retention. In Exp. 2, 15 lambs (34 +/- 4 kg initial BW) fitted with indwelling catheters in a hepatic vein, the hepatic portal vein, a mesenteric vein, and a mesenteric artery were used. Release of ammonia N by the portal-drained viscera (PDV) was reduced (P = 0.004) in alternate-day-supplemented lambs compared with RDP-D. Consequently, hepatic uptake of ammonia N was least (P = 0.003) in all alternate-day lambs. Alpha-amino nitrogen (AAN) release by the PDV and hepatic uptake of AAN were not affected by treatment or supplementation frequency. Additionally, hepatic output and PDV uptake of urea N were not affected by treatment. Hepatic N uptake (ammonia N + AAN) accounted for urea synthesized by the liver in all treatments; however, hepatic urea synthesis was approximately 4.5-fold less for RUP-A lambs. This suggests that the provision of AA as RUP may provide a delay in ureagenesis, thus altering the timing of N recycling.

Seasonal changes in one seed juniper intake by sheep and goats in relation to dietary protein and plant secondary metabolites

Plant secondary metabolites (PSM) and nutrients can influence patterns of feed intake of small ruminants. Their effects depend on the type and amounts of PSM and nutrients fed. We hypothesized that one-seed juniper intake of goats and sheep would change in response to seasonal variations of PSM concentrations and type and amount of CP fed. To test this hypothesis, we fed 12 does (46.7 ± 1.25 kg) and 12 ewes (74.9 ± 1.23 kg) freshly harvested one-seed juniper branches in summer, fall, winter, and spring. Animals also received isoenergetic diets (1.6% BW) with either addition of a high rumen degradable (RDP, 12.5% CP) or undegradable (RUP, 12.5% CP) protein source or with no addition of supplemental protein (Control, 5% CP). Juniper branches were offered in unrestricted amounts for 30 min prior to feeding treatment diets and short-term intake was determined for 10 d per season. One-seed juniper leaves contained a diverse mix of terpenes, phenolics, and condensed tannins which were positively correlated to each other ( P < 0.05) and varied seasonally in concentration and composition ( P < 0.05). Juniper intake was greater for goats than sheep ( P < 0.05), and twice as high for animals fed high CP diets vs. control animals ( P < 0.05). Juniper intake in the fall, when levels of plant secondary metabolites were highest, was 41, 58, and 52% less ( P < 0.05) than in summer, winter, and spring, respectively. Addition of high RDP and RUP sources into diets induced different patterns of juniper intake across seasons, herbivores, and individual animals. In each diet treatment, a distinct subset of a few PSM explained 30–78% of overall variation in juniper intake of goats and sheep. This study suggests that increases in dietary protein levels can increase voluntary intake of one-seed juniper of small ruminants during seasons when PSM levels are low. Diets with protein sources of different degradability can potentially influence juniper intake of small ruminants differently, probably due to different nutrient–PSM associations that may result in different detoxification capabilities and post-ingestive experiences that influence individual juniper preference.

Proteolysis in alfalfa silages made from different cultivars

During silage fermentation, proteolysis reduces the nutritional value of N, particularly in alfalfa. This study evaluated the proteolysis of 27 alfalfa cultivars seeded in triplicate in 2 consecutive years. Forage from each plot was wilted to a targeted dry matter (DM) content of 250 g kg–1 and ensiled in laboratory silos. Minisilos were made with spring growth and summer regrowth in the first year of production for the first seeding, and with the first 2 yr of production for the second seeding, giving 3 harvest years altogether. Concentrations of NPN, NH3, FAA, DM, TN, and pH were measured in silages, whereas RUP concentration was evaluated in forages. Low NPN concentration indicates low proteolysis during silage fermentation. Spring growth and summer regrowth were analyzed separately by ANOVA as a completely randomized block design replicated over 3 harvest years. A principal component analysis was then performed on the ANOVA means. Silage DM was used as covariate when it was deemed appropriate. There was a significant variation among cultivars for NPN concentration in silages made of summer regrowth; it varied from 612 to 717 g kg–1 of TN. Concentration of NPN was significantly lower for cultivars WL 225, Rangelander, Iroquois, and WL 222, and higher for cultivars Oneida VR, Arrow, Vernal, Spredor 2, and Armor. Oneida VR and Rangelander had respectively high and low silage NPN concentration in both spring growth and summer regrowth. From cultivars with low silage NPN concentration, Rangelander was the only one with high forage RUP concentration in both spring growth and summer regrowth; proteins in this cultivar would be more resistant to microbial degradation during ensiling and in the rumen. Key words: Non protein nitrogen; proteolysis; alfalfa silage; cultivars

Soybeans Versus Animal Sources of Rumen-Undegradable Protein and Fat for Early Lactation Dairy Cows

Fifteen multiparous Holstein cows averaging 39 DIM were used in a replicated 5 × 5 Latin square design to compare roasted soybeans and animal by-products as supplements for increasing the RUP content of lactation diets based on alfalfa. The control diet contained roasted soybeans and was formulated to meet requirements for RUP. Rumen-undegradable protein in the diet was increased by including additional roasted soybeans or animal by-product proteins. To achieve diets with similar amounts of fat, we added tallow, hydrolyzed tallow fatty acids, or partially hydrogenated tallow to the control diet and to diets containing animal by-product proteins. Control diets and diets with high RUP were estimated to be 5.8 and 7.6% RUP (DM basis). The RDP of all diets was estimated to be approximately 11.3% of DM. Milk yield was increased by additional dietary RUP. Yield of FCM was greater for cows receiving animal by-products than for those fed additional roasted soybeans. Cows fed additional RUP yielded more milk protein, but milk protein percentage was decreased. Milk fat percentage was reduced by additional dietary RUP, but fat yield was not affected. Nutrient digestibility was greatest for diets containing animal by-products. Cows fed tallow yielded more milk, FCM, and protein that did those fed hydrolyzed tallow fatty acids or partially hydrogenated tallow. Lactation performance can be enhanced by supplementing animal by-products or roasted soybeans to diets based on alfalfa and formulated to meet NRC recommendations for RUP.

Effect of Type of Protein Supplementation on Duodenal Amino Acid Flow and Absorption in Lactating Dairy Cows

Four multiparous lactating Holstein cows, fitted with cannulas in the rumen, duodenum, and ileum, were used in a trial with a 4 × 4 Latin square design to examine the effect of source and degradability of dietary CP supplements on AA flow and absorption in the small intestine. The CP supplements consisted of fish meal or meat meal as the animal by-products supplement and soybean meal or heated soybean meal as the plant by-products supplement. Fish meal and heated soybean meal constituted the high RUP diets, and meat meal and soybean meal constituted the low RUP diets.Dry matter intakes were similar among treatments. However, intakes of OM, rumen-degradable OM, total CP, and RDP were affected by the source of the CP supplement and were higher for diets with plant by-products than for those diets with animal by-products. Data were similar for the calculated in situ digestibilities and for true in vivo digestibilities of rumen-degradable OM. Efficiency of bacterial CP synthesis was similar among diets; however, nonbacterial CP flow to the duodenum and OM, CP, and disappearance of AA from the small intestine were affected by the interaction of supplement source and degradability. Heat treatment of soybean meal reduced the availability of most of the essential AA for absorption in the small intestine by 2.3% compared with that of soybean meal; the biggest such reduction (20%) occurred for Met.Availability of AA in the small intestine was affected by source and degradability of the CP dietary supplement. Heat treatment at 140°C for 2.5h reduced the availability of Met absorption from the small intestine. Although the differences among availabilities of the individual AA in the small intestine ranged from 80 to 84% among treatments, for high yielding cows, these differences may have practical significance.