Levels Of Rumen Undegradable Protein Research Articles

Effect of feeding different levels of rumen undegradable protein on growth and economics of production in female crossbred calves

Effect of feeding different levels of rumen undegradable protein on growth and economics of production in female crossbred calves

Effect of Tannin Inclusion on the Enhancement of Rumen Undegradable Protein of Different Protein Sources

Tannins can be utilized to increase rumen undegradable protein (RUP) by their capacity to form complexes with diverse nutrients present in the feed. In that regard, high-performance ruminants demand elevated RUP levels. The objective of this study was to evaluate the effects of incorporating varying levels of tannin into three protein sources (cottonseed, peanut, and soybean meals) on ruminal kinetic parameters, ruminal fermentation, and intestinal digestibility. Thus, three in situ experiments were conducted to investigate the ruminal degradation kinetics, where Fraction A represents the soluble portion, Fraction B relates to the portion potentially degraded in the rumen, and kd denotes the degradation rate of Fraction B, for both dry matter (DM) and crude protein (CP) in the rumen. Additionally, the study assessed dry matter effective degradability (ED), rumen undegradable protein (RUP), and intestinal digestibility (ID). These experiments utilized three cannulated animals for the in situ incubations. Regarding cottonseed meal in terms of DM degradation kinetics, tannin inclusion had a quadratic effect on fraction A (p < 0.01), B (p = 0.10, trend), kd (p = 0.03), and ED (p < 0.01). Fraction A of CP had a cubic effect (p = 0.03), being greater for the control compared with the other treatments. The inclusion of tannin linearly increased RUP (p < 0.01). The RUP proportion increased 29, 33, and 45% when 20, 40, and 60 g/kg tannin were used, respectively, compared to the control. For peanut meal, the A fraction of protein and RUP responded quadratically as tannin was included in peanut meal (p < 0.01). However, tannin levels did not affect fraction B of protein and ID. Regarding soybean meal, fractions A and B of DM and ED had cubic effects (p < 0.01), being greater for the control compared with the other treatments, and responded quadratically as tannin increased. Also, tannin inclusion had a cubic effect on fractions A and B of protein, RUP, and ID (p < 0.01). The cubic behavior showed greater B fraction and ID and lower A fraction and RUP for the control compared other treatments (p < 0.01). Tannins offer a promising avenue for elevating RUP levels in diets featuring cottonseed and peanut meals. Nevertheless, no advantages were observed when treating soybean meal with tannin.

Influence of flaxseed with rumen undegradable protein level on milk yield, milk fatty acids and blood metabolites in transition ewes

An experiment was conducted to determine the effects of two levels of rumen undegradable protein (RUP) without or with whole or extruded flaxseed on milk yield, milk component, milk fatty acids (FAs) profile and plasma metabolites in transition ewes. Three weeks before and after lambing, seventy-two Baluchi ewes were used in a completely randomized design with a 3 × 2 factorial arrangement of treatments. The treatments contained 1) no flaxseed + 20% RUP (no flaxseed, low RUP [NFLR]); 2) no flaxseed + 40% RUP (no flaxseed, high RUP [NFHR]); 3) 10% whole flaxseed + 20% RUP (whole flaxseed, low RUP [WFLR]); 4) 10% whole flaxseed + 40% RUP (whole flaxseed, high RUP [WFHR]); 5) 10% extruded flaxseed + 20% RUP (extruded flaxseed, low RUP [EFLR]), and 6) 10% extruded flaxseed + 40% RUP (extruded flaxseed, high RUP [EFHR]). Ewes fed 10% extruded flaxseed exhibited higher (p < 0.001) dry matter intake (DMI) and colostrum yield (p < 0.1) compared to other treatments. Two types of flaxseed and RUP levels had no significant effect on milk yield, but milk fat and protein contents decreased and increased in diets containing 40% RUP, respectively. Ewes fed extruded flaxseed produced milk with lower concentrations of saturated fatty acids (SFA) and higher α-linolenic and linoleic acids and also polyunsaturated fatty acids (PUFA) compared to other groups (p < 0.05). During post-lambing, the ewes fed diets containing flaxseed exhibited higher concentration of serum non-esterified FAs (NEFA) compared to diets without flaxseed (p < 0.01). The concentration of serum β-hydroxybutyric acid (BHBA) decreased in the diets containing flaxseed types at pre-lambing, but increased in diets containing extruded flaxseed at post-lambing (p < 0.01). The serum glucose concentration of ewes (pre and post-lambing) which consumed diets containing extruded flaxseed or 40% RUP increased, but blood urea concentration was elevated following supplementation of diet with whole flaxseed or 40% RUP (p < 0.001). In conclusion, utilization of 10% extruded flaxseed in the diets of transition ewes had positive effects on animal performance with favorable changes in milk FAs profile. However, there is no considerable advantage to supply more than 20% RUP level in the diet of transition dairy sheep.

Interaction of dietary rumen undegradable protein level and supplemental rumen-protected conjugated linoleic acid on performance of growing goat kids

Abstract This study aimed to investigate the effects of dietary rumen undegradable protein (RUP) level and supplemental rumen protected conjugated linoleic acid (rpCLA) on performance, nutrient digestibility, rumen fermentation, urinary purine derivatives and plasma metabolites in growing kids. Thirty-two Kurdish kids (13.06 ± 1.08 kg BW) were fed diets differing in RUP level (low = 250 vs. high = 350 g/kg of dietary CP) supplemented either with 15 g/kg rpCLA or 12 g/kg of hydrogenated soybean oil (HSO). The experiment was lasted for 100 days including a 20-d of adaptation period. Goat kids fed diet containing high RUP supplemented with rpCLA had the lowest dry matter intake, but the greatest average daily gain and feed efficiency compared to the other groups (P ≤ 0.05). The interaction of dietary RUP level and rpCLA supplementation had no effect on organic matter, crude protein and ether extract digestibility and ruminal fermentation parameters (P > 0.05). Goat kids fed diet containing high RUP supplemented with HSO had the greatest plasma concentration of triglycerides compared to the other groups (P ≤ 0.05). Urinary uric acid and allantoin concentrations were not influenced by the experimental diets (P > 0.05). In conclusion, feeding diet containing high RUP level supplemented with 15 g/kg rpCLA improved production performance of growing goat kids.

Effects of reducing crude protein concentration in starter feed containing constant rumen undegradable protein on dairy calves performance.

This study aimed at investigating the effects of decreasing crude protein (CP) in diets with constant rumen undegradable protein (RUP) content on dry matter (DM) intake, growth, feed efficiency (FE) and blood parameters in calves in a randomized complete block design. Dietary treatments included: (a) a calf starter containing 200g/kg CP (62g/kg RUP, based on DM), (b) a starter containing 180g/kg CP (65g/kg RUP, based on DM) and (c) a starter containing 160g/kg CP (65g/kg RUP, based on DM). A total 42 newborn male and female Holstein calves were fed 8L milk/day until day 45, after which they were weaned and continued the experiment until day 75. Solid feed intake and total DM intake were measured daily, and body weight and skeletal growth parameters including withers height and heart girth were recorded weekly. Blood samples were collected on days 45 and 75. Solid feed intake, total DM intake, weaning weight, average daily gain from birth to weaning and from birth to 75days, final weight and FE were not affected by the experimental treatments. In addition, skeletal growth parameters were similar among groups. Glucose concentration was similar among treatments; however, calves fed the starter containing 160g/kg CP had significantly lower plasma concentrations of albumin and urea nitrogen compared with those fed starters containing 180 and 200g/kg CP. These results indicate that CP level in the calf starter could be decreased to 160g/kg DM if RUP levels stay at 65g/kg DM, without negatively affecting feed intake and calf performance.

Supplementation with different non-fiber carbohydrate sources in dairy cow diets with high or low rumen-undegradable protein content

ABSTRACT The objective for this study was to evaluate the supplementation with different non-fibrous carbohydrate (NFC) sources for grazing dairy cows in diets with high or low concentrations of rumen undegradable protein (RUP). Twelve multiparous cows averaging 30kg/d of milk production and 45±23 days in milk in a 4x4 Latin square design with 2 × 2 factorial arrangement were used. The difference in NFC content of the diets was achieved using ground corn (GC) or dried citrus pulp (DCP). Dietary RUP was altered by the partial replacement of soybean meal (LRUP) by roasted whole soybean and corn gluten meal (HRUP). Greater dry matter intake (DMI) was observed in DCP treatments compared to GC treatments (19.2 and 17.7kg/day of DM, respectively). Milk fat concentration was lower for LRUP treatments (3.4%) when compared to HRUP (3.6%). The milk protein concentration was greater for GC treatments (2.9%) in relation to DCP treatments (2.8%). Lower milk ureic nitrogen was observed when DCP diets were fed compared to those with GC (17.8 and 21.2mg/dL, respectively). The use of DCP as CNF source increased dry matter intake as well as milk fat concentration, although no differences in milk production were observed for RUP level.

Nutrient digestibility, nitrogen excretion, and milk production of mid-lactation Jersey × Friesian cows fed diets containing different proportions of rumen-undegradable protein.

The present study was planned to test the hypothesis that feeding lactating dairy cattle with varying levels of rumen-undegradable protein (RUP) can enhance protein utilization, milk production, milk protein, and nitrogen (N) excretion. Forty mid-lactating crossbred (Jersey × Friesian) cattle were randomly divided into four groups. Four treatment diets were formulated to contain 30%, 40%, 50%, and 60% RUP of crude protein. Dry matter (DM) and crude protein intakes were significantly reduced with increasing dietary RUP levels. Crude protein digestibility increased linearly with incremental increases in dietary RUP levels. Cattle fed 60% RUP showed a linear decrease in N intake compared to that in the other groups. A linear decrease in urinary N and linear increases in net N, milk N, and N-use efficiency were observed with increasing dietary RUP levels. Actual milk, energy-corrected milk, and 4% fat-corrected milk yields (kg/day) increased linearly with an increasing degradability of protein. However, milk protein, solids not fat and total solids, as well as the yields of protein, fat, and lactose, showed significant increases with increased RUP supplementation. Collectively, the results indicate that formulating dairy cow diets to contain 60% RUP results in better lactating performance and N-use efficiency and lower N excretion.

Interaction effect of ruminal undegradable protein level and rumen-protected conjugated linoleic acid (CLA) inclusion in the diet of growing goat kids on meat CLA content and quality traits.

The aim of the present study was to determine the effects of dietary rumen undegradable protein (RUP) level and rumen-protected conjugated linoleic acid (rpCLA) on meat fatty acid (FA) profile, chemical compositions and colour parameters of growing kids. Thirty-two Kurdish goat kids (13·06 ± 1·08 kg body weight) were fed diets differing in RUP level (low = 250 v. high = 350 g/kg of dietary crude protein) supplemented either with 15 g/kg of rpCLA or 12 g/kg of hydrogenated soyabean oil (HSO) for 80 d. Interaction of dietary rpCLA and RUP level had no effect on hot carcass weight, dressing and cut percentage, and meat chemical composition and colour parameters. Meat total SFA, MUFA and PUFA concentrations were not influenced by experimental diets, whereas kids fed diets supplemented with rpCLA had lower meat total SFA and higher PUFA concentrations compared with those fed diets supplemented with HSO. The concentration of meat trans-11-8 : 1 was not influenced by rpCLA supplementation, RUP level and their interaction. Kids fed diets containing rpCLA supplementation had higher meat total CLA and cis-9, trans-11-CLA and trans-10, cis-12-CLA isomers compared with those fed diets containing HSO supplementation. Desaturase indexes of C14, C16 and C18 were not influenced by rpCLA supplementation, RUP level and their interaction. It is concluded that supplementing growing kids' diets with RUP and 15 g/kg of rpCLA not only decreased meat fat content but also increased some FA considered to be of potential benefit to human health.

Effects of rumen undegradable protein on intake, digestibility and rumen kinetics and fermentation characteristics of dairy heifers

The aim of this work was to evaluate the influence of increasing amounts of rumen undegradable protein (RUP) on intake, nutrient digestibility, rumen kinetics and fermentation characteristics and N use efficiency of dairy Holstein heifers. Eight rumen-cannulated Holstein heifers (initial body weight 276 ± 8.3 kg) were used in a replicate 4 × 4 Latin square design with four dietary RUP amounts in the total dietary protein, as follows: 38% of RUP (38RUP), 44% of RUP (44RUP), 51% of RUP (51RUP) and 57% of RUP (57RUP). The experimental period was 84 days, subdivided into four periods of 21 days (14 days for adaptation + 7 days for collections). Eight spot collections of faeces, urine, ruminal content and omasal digesta were performed at 9-h intervals, as follows: on 15th day samples were collected at 0600 h and 1500 h; on 16th day samples were collected at 0000 h, 0900 h and 1800 h; on 17th day samples were collected at 0300 h, 1200 h and 2100 h. Two complete rumen evacuations were performed: one on 19th day 4 h after morning feeding and another on 21st day immediately before morning feeding. Total (kg/day) and relative (g/kg of body weight) intake of dry matter, crude protein (CP), neutral detergent fibre corrected for ash and protein were not affected (P > 0.10) by dietary RUP amounts. Ruminal (P = 0.06) and intestinal (P = 0.09) digestibilities of CP presented a tendency to decrease with increasing RUP. There were no effects of dietary RUP amounts (P > 0.10) on the rates of ingestion, passage and digestion (%/h) as well on the total volatile fatty acid concentration in the rumen. Urinary N excretion presented a tendency (P = 0.08) to decrease with increasing RUP. In addition, retained N presented a tendency (P = 0.09) to increase according to dietary RUP amounts and greater values were observed for treatments 51RUP and 57RUP. Microbial protein synthesis, microbial efficiency and the efficiency of use of N for microbial synthesis decreased with increasing RUP (P < 0.05). Metabolisable protein flow presented a tendency to increase (P = 0.091) and greater values were observed for 51RUP and 57RUP. In general, urinary N excretion decreased, while the flow of metabolisable protein and RUP increased with increasing RUP levels. As a consequence of this pattern, the treatments 51RUP and 57RUP presented increases in the retained N.

Effects of rumen-undegradable protein on intake, performance, and mammary gland development in prepubertal and pubertal dairy heifers

The objective of this study was to evaluate the influence of different amounts of rumen-undegradable protein (RUP) on intake, N balance, performance, mammary gland development, carcass traits, and hormonal status of Holstein heifers at different physiological stages (PS). Sixteen prepubertal (PRE) heifers (initial BW = 106 ± 7.6 kg; age = 4.3 ± 0.46 mo) and 16 pubertal (PUB) heifers (initial BW = 224 ± 7.9 kg; age = 12.6 ± 0.45 mo) were used in an experiment over a period of 84 d. Four diets with increasing RUP contents (38, 44, 51, and 57% of dietary crude protein) and heifers at 2 PS (PRE or PUB) were used in a 4 × 2 factorial arrangement of treatments in a completely randomized design. Throughout the experiment, 2 digestibility trials were performed over 5 consecutive days (starting at d 36 and 78) involving feed and ort sampling and spot collections of feces and urine. At d 0 and 83, body ultrasound images were obtained for real-time carcass trait evaluation. The mammary gland was ultrasonically scanned at d 0 and every 3 wk during the experiment. Blood samples were taken at d 0 and 84 to determine serum concentrations of progesterone, estrogen, insulin-like growth factor I (IGF-I), and insulin. No interaction between PS and the level of RUP was found for any trait. Apparent digestibility of dry matter, organic matter, and neutral detergent fiber corrected for ash and protein was not affected by RUP level but was lower for PRE compared with PUB heifers. Sorting against neutral detergent fiber corrected for ash and protein (tendency only) and for crude protein was greater for PUB than PRE heifers. Pubertal heifers had greater average daily gain (905 vs. 505 g/d) and N retention (25.9 vs. 12.5 g/d) than PRE heifers. In addition, average daily gain and N retention were greatest at 51% RUP of dietary protein. Mammary ultrasonography indicated no effects of RUP amounts on mammary gland composition, whereas PRE heifers had greater pixel values than PUB, indicating higher contents of fat rather than protein in the mammary glands of PRE heifers. Serum progesterone and IGF-I concentration was affected only by PS, and PRE heifers had greater values of progesterone and IGF-I concentrations than PUB heifers. Serum insulin concentration was unaffected by PS but tended to be higher at 51% of RUP. In conclusion, an RUP level of 51% increases body weight, average daily gain, feed efficiency, and N retention in heifers regardless of the PS. In addition, PRE heifers have a lower sorting ability and reduced intake, total-tract digestibility, and N retention. They also have higher amounts of fat in their mammary glands, even at moderate growth rates.

Lowering rumen-degradable and rumen-undegradable protein improved amino acid metabolism and energy utilization in lactating dairy cows exposed to heat stress

The objective of this study was to evaluate the effects of reducing dietary rumen-degradable protein (RDP) and rumen-undegradable protein (RUP) on protein and energy metabolism in heat-stressed dairy cows. Eighteen primiparous and 30 multiparous mid-lactation Holstein cows were used in a completely randomized design arranged in a 2 × 2 factorial (n = 12/treatment). Cows were randomly assigned to 1 of 4 dietary treatments that included 2 levels of RDP (10 and 8%; D) and 2 levels of RUP (8 and 6%; U) of dry matter for 21 d as (1) 10D:8U, (2) 8D:8U, (3) 10D:6U, and (4) 8D:6U. Diets were isoenergetic and contained 50% forage and 50% concentrate (dry matter basis). Cows were housed in a freestall barn. Three weeks before start of treatments, all animals were fed the 10D:8U diet and received supplemental cooling to prevent heat stress. During the treatment period, cows experienced a daily increment in temperature-humidity index from 74 to 82 for 1000 to 2000 h. Blood samples were collected on d -1 and 21 of the treatment period to determine plasma concentrations of AA, glucose, insulin, fatty acids, and β-hydroxybutyrate. For primiparous cows, reducing from 10 to 8% RDP decreased insulin concentrations. For multiparous cows, we found significant RDP by RUP interactions for insulin, β-hydroxybutyrate, fatty acids, total essential AA, and 3-methylhistidine concentrations. Reducing from 10 to 8% RDP decreased insulin concentrations at 6% RUP, but concentrations did not change when reducing RDP at 8% RUP. Reducing from 10 to 8% RDP decreased β-hydroxybutyrate concentrations at 8% RUP, but concentrations did not change when reducing RDP at 6% RUP. Reducing from 10 to 8% RDP increased nonesterified fatty acid and total essential AA concentrations at 8% RUP, but concentrations did not change when reducing RDP at 6% RUP. Reducing from 8 to 6% RUP decreased 3-methylhistidine concentration at 8% RDP, but not at 10% RDP. Reducing from 8 to 6% RUP increased milk protein yield efficiency in primiparous and multiparous cows. These results indicate that reducing RDP and RUP lowers circulating insulin, which was associated with mobilization and utilization of fatty acids. Reduced RDP and RUP increases the use of AA to maintain milk protein synthesis and limit AA catabolism in cows exposed to warm climates.

350 Corn silage rumen undegradable protein levels and extent of digestion

350 Corn silage rumen undegradable protein levels and extent of digestion

Kinetics of digestion of low-quality forage grazed by beef cattle fed supplements containing increasing levels of rumen undegradable protein

This experiment was conducted to evaluate the degradation kinetics and microbial efficiency of beef cattle grazing on low-quality forage and receiving supplements with different levels of rumen undegradable protein (RUP). The animals grazed on palisade grass pasture solely or this pasture and supplement containing 40 or 60 g of RUP per 100 g of crude protein (CP). The degradation profiles of neutral detergent fiber, fiber carbohydrates, and neutral detergent insoluble protein were interpreted kinetically by using a decreasing logistic model. Treatments (no supplement, or RUP at 40 or 60 g−1 100 g CP) did not affect rumen fill; however, the increase in the indigestible fiber carbohydrate fraction that occurred at the expense of the digestible fiber carbohydrate fraction resulted in a greater rumen fill effect. The palisade grass showed a significant proportion of its nitrogen in the form of slowly degradable protein as neutral detergent insoluble protein, which amounted to 26 g per 100 g CP. Supplementation with 40 g of RUP per 100 g CP decresead the indigestible fraction of the low-quality forage. However, the absence of a rumen-fill effect demonstrates that the additional supply of nutrients contributes greatly to increasing growth efficiency and use of the available energy from the forage by the ruminal microorganisms.

Nutrient digestibility and growth of five breeds of sheep under different levels of undegradable protein

A study was conducted to evaluate the effect of feeding different levels of rumen undegradable protein (UDP) in concentrate on performance of five breeds of sheep. Namely: Compass Agrinak (CA); Garut Composite breed (KG); Barbados Cross breed (BC); St Croix breed (SC); and Local Garut (GL) breed. Ten heads of sheep were used from each breed, in which each breed was grouped into 5 groups according to their body weight, and each sheep in each group was assigned to one of two treatments diet. The diet treatment consisted of concentrate containing different levels of undegradable protein (UDP). The levels of undegradable protein were 4.5% and 7.5%. Concentrate were formulated in iso nitrogen (CP content 16.7%) and iso energy (ME content 2.5 Mcal/kg). During feeding trial the sheep were kept in individual pen for three months. Study was conducted in randomized complete block design in factorial 5 x 2 arrangement, 5 levels of breeds sheep and 2 levels of UDP content. Results shows that there was no interaction effect of breed and levels UDP on feed consumption, average daily gain and feed conversion. These variables were significantly (P 0.05) by interaction between breed of sheep and UDP levels in the diet except for OM digestibility. While breed of sheep did not affect nutrient digestibility and UDP levels only affected NDF digestibility. From this study, it is concluded that increasing UDP in the diet did not improve growth performance of sheep. At similar quality of feed the growth performance was affected by breed of sheep in which KG and GL sheep had similar average daily gain (86.01 vs 82.38 g/day).

Novel coproducts from corn milling and their use in ruminants’ nutrition

The article reviews published data on two novel coproducts originating from corn milling: high-protein distillers' grain (HPDG) and reduced-fat distillers' grain (RFDG). Based on a literature survey over the last decade, this article focuses on their chemical composition and, consequently, nutritive value and on the effects of their inclusion in ruminants' diets on rumen activity and animal performance. Compared to the classic distillers' grains, the two new coproducts expressed lower variability of their chemical composition, nutritive value, and specific feeding characteristics, allowing more targeted feeding strategies (protein balancing, avoidance of milk fat depression, etc.). Thus, HPDG has significantly higher crude protein content (~44%), lower fat content (~4.3%), and lower fibre content (~26.8% neutral detergent fibre (NDF) and ~12.3% acid detergent fibre (ADF)) compared to the classical distillers grains. In the case of RFDG, only the fat content is significantly lower (~4.8%), whereas the crude protein content (~32.1%) and the fibre content (~36.1% NDF and ~14.7% ADF) are only slightly lower compared to the classical distillers grains. On this basis, HPDG can successfully replace classic high-protein meals, such as soybean meal, thus providing high levels of rumen undegradable protein, although it has the same amino acid limitations as the originating raw material, corn grains. The use of RFDG instead of the classical distillers' grains allows much higher dietary inclusion, without adverse effects on rumen metabolism and animal performances. A further development of the two coproducts and further diversification of corn coproducts, allowing better solutions to various feeding situations, is expected.

에너지 및 반추위 미분해단백질 수준을 달리한 사료급여가 비유중기 유우에 미치는 영향

Sources of energy and rumen undegradable protein (RUP) have been used to meet nutrient requirements for high producing dairy cows. However studies for manipulation the levels of energy and RUP in diets have been mainly achieved using dairy cows at early-lactation period. The objective of this study thus, was to investigate the effects of different energy and rumen undegradable protein (RUP) levels on dry matter intake and milk yield in Holstein cows at mid-lactation period. Basal diet was prepared as TMR to meet nutrient requirements for dairy cows at mid-lactation according to NRC recommendation. Cows of control group (Con) were fed only basal diets while ground corn (0.5 kg/d), heat-treated soybean meal (0.5 kg/d), and their mixture (0.25 kg of each supplements/d) were added to diets for cows of treatment groups (T1, T2, and T3 respectively) to modulate the level of energy and RUP contents in diets. Addition of energy or RUP source in basal TMR did not affect in total DMI while TMR intake tended to be higher in Con compared to T3. Cows fed T3 diets tended to show increased milk yield and MUN content than those of Con. Cows for T2 as well as T3 had lower ADG (P<0.05) compared with those of Con. We concluded that the addition of RUP source in diets for dairy cows on mid-lactation period might cause the decrement of DMI and ADG.

Effects of Increasing Rumen‐Undegradable Protein Supplementation Levels on Early Weaned Calves Grazing Stargrass

Early weaned beef calves (Bos spp.) grazing warm‐season grasses may benefit from increasing levels of rumen‐undegradable protein (RUP) supplementation due to the limited RUP supplied by the forage and their high nutrient requirements. The objective of this study was to test the effects of increasing levels of RUP supplementation on performance of early weaned calves grazing stargrass (Cynodon nlemfuensis Vanderyst) pastures. The experiment was conducted in Ona, FL, from May to August 2007 and 2008. Treatments were 1.5 g kg−1 body weight (BW) of three levels of supplemental RUP from soybean [Glycine max (L.) Merr.] meal (SBM) (350 g kg−1 RUP), Soyplus (SP) (600 g kg−1 RUP) (a modified expeller SBM) (West Central, Ralston, IA), or a 50:50 mixture of SBM and Soyplus (SBMSP) (475 g kg−1 RUP). Pasture size was 0.51 ha and four early weaned calves were assigned to each pasture. There was no effect of the treatments on mean herbage mass (HM; 2.7 Mg ha−1), forage crude protein (CP) (171 g kg−1), in vitro digestible organic matter (IVDOM) concentration (640 g kg−1), or calf average daily gain (0.56 kg d−1). Increased RUP supplementation did not affect forage dry matter intake (mean = 2.0% BW); however, there was a linear decrease in apparent dry matter digestibility from 640 to 600 g kg−1. Increasing levels of RUP supplementation may not increase performance of early weaned calves grazing stargrass pastures when forage CP is not limiting.

Effect of Rumen Undegradable Protein Levels on Performance of Thai Native x Brahman Beef Cattle

2 Abstract: This experiment aimed to study the effects of rumen undegradable protein levels on productive performance of Thai Native-Brahman beef cattle. Four yearling Thai Native x Brahman beef cattle with an average Body Weight (BW) of 175.5±18.6 kg were used in a 4 x 4 Latin square arrangement. The treatments were levels of Rumen Undegradable Protein (RUP) in concentrate at 30, 35, 40 and 45%. Concentrates were formulated to contain 14% CP and were fed at 2.0% BW. The results showed that the DM intake, OM digestibility and TVFA increased linearly (p<0.05) while the level of RUP increased. Moreover, the ruminal NH3-N (p<0.01) and BUN linearly decreased, whereas at 45% RUP the ruminal NH3-N concentratio n increased (quadratically, p<0.01). The bacteria and protozoa populations also increased as the level of RUP increased. However, the bacteria and protozoa populations decreased quadratically (p<0.05) when the level of RUP changed from 40 to 45%. The N retention (g/d) tended to increase with increasing the level of RUP. However, the N retention tended to decrease at the level of 45% RUP. It could be concluded that RUP level at 40% in concentrate had positive effects on productive performances.

Rumen‐Undegradable Protein Supplementation Effects on Early Weaned Calves Grazing Annual Ryegrass

Early weaned beef calves (Bos spp.) can be raised on cool‐season pastures in Florida but more information on protein supplementation is necessary to optimize the performance of those calves. The objective of this study was to evaluate the effects of three levels of rumen‐undegradable protein (RUP) supplementation on performance of early weaned calves grazing annual ryegrass (Lolium multiflorum Lam.) pastures. The study was conducted in Ona, FL in 2007 and 2008. Treatments were 1.5 g kg−1 body weight (BW) supplementation of three levels of supplemental RUP, soybean meal (SBM, 350 g kg−1 RUP), Soyplus (SP, 600 g kg−1 RUP, modified expeller soybean meal, West Central, Ralston, IA), or a 50:50 mixture of soybean meal‐Soyplus (SBMSP, 475 g kg−1 RUP). Pasture size was 0.3 ha and four early weaned calves were assigned to each pasture. There was a linear increase in herbage mass (HM, from 1.9–2.1 Mg ha−1) and herbage allowance (HA, from 1.1–1.4 kg dry matter [DM] kg−1 live weight, LW) with increasing levels of RUP. Increased RUP supplementation decreased forage dry matter intake (FDMI) and total dry matter intake (TDMI) in 2008 but there was no effect in 2007. There was no difference in average daily gain (ADG, 0.76 kg d−1) among treatments. Increasing the levels of RUP supplementation has potential to increase stocking rates of early weaned calves grazing annual ryegrass pastures.

Effect of protein degradability on milk production of dairy ewes

The objective of this experiment was to determine the effect of protein degradability of dairy sheep diets on milk yield and protein utilization across 2 levels of milk production. Three diets were formulated to provide similar energy concentrations and varying concentrations of rumen-degradable protein (RDP) and rumen-undegradable protein (RUP): 12% RDP and 4% RUP (12-4) included basal levels of RDP and RUP, 12% RDP and 6% RUP (12-6) included additional RUP, and 14% RDP and 4% RUP (14-4) included additional RDP. Diets were composed of alfalfa-timothy cubes, whole and ground corn, whole oats, dehulled soybean meal, and expeller soybean meal (SoyPlus, West Central, Ralston, IA). Estimates of RDP and RUP were based on the Small Ruminant Nutrition System model (2008) and feed and orts were analyzed for Cornell N fractions. Eighteen multiparous dairy ewes in midlactation were divided by milk yield (low and high) into 2 blocks of 9 ewes each and were randomly assigned within block (low and high) to 3 pens of 3 ewes each. Dietary treatments were arranged in a 3×3 Latin square within each block and applied to pens for 14-d periods. We hypothesized that pens consuming high-RUP diets (12-6) would produce more milk and milk protein than the basal diet (12-4) and pens consuming high-RDP diets (14-4) would not produce more milk than the basal diet (12-4). Ewes in the high-milk-yield square consumed more dry matter and produced more milk, milk fat, and milk protein than ewes in the low-milk-yield square. There was no effect of dietary treatment on dry matter intake. Across both levels of milk production, the 12-6 diet increased milk yield by 14%, increased milk fat yield by 14%, and increased milk protein yield by 13% compared with the 14-4 and 12-4 diets. Gross N efficiency (milk protein N/intake protein N) was 11 and 15% greater in the 12-6 and 12-4 diets, respectively, compared with the 14-4 diet. Milk urea N concentration was greater in the 12-6 diet and tended to be greater in the 14-4 diet compared with the 12-4 diet, indicating that the excretion of urea N in this study was more closely related to dietary crude protein concentration than to protein degradability.