Replacement of wheat bran with spineless cactus (Opuntia ficus indica Mill cv Gigante) and urea in the diets of Holstein x Gyr heifers

The aim of this study was to evaluate the replacement effect of wheat bran with spineless cactus and urea in heifers. Twenty-four heifers with an average initial weight of 185?±?13 kg were used in this experiment. Four levels of spineless cactus corrected with urea and ammonium sulfate (9:1) were studied: 0, 33, 66, and 100 % replacement with wheat bran. Samples of feed, orts, and feces were analyzed to estimate the intake and digestibility of dry matter (DM) and nutrients. Indigestible neutral detergent fiber was used as an internal marker. The experiment was conducted in a completely randomized design. Dry matter, neutral detergent fiber, and total digestible nutrient intake demonstrated a quadratic effect (P?P?P?相似文献   

Effect of field pea (Pisum sativum L.) level on intake,digestion, ruminal fermentation and in vitro gas production in sheep fed maintenance diets

The objective of this study was the characterization of the nutritive value, ruminal fermentation and nutrient digestibility of field pea (Pisum sativum L.) hay (FPH) by‐product through in situ, in vitro and in vivo tests. A FPH diet was administered ad libitum to four sheep (live weight (LW) 38.0 ± 2.0 kg) at four inclusion levels (0, 25, 50 and 75%) over a conventional sorghum grain/oat straw ration in a 4 × 4 Latin square design. The in situ degradability of FPH was 67% dry matter (DM), 71% crude protein and 66% neutral detergent fiber (NDF). The inclusion of FPH did not affect (P ≥ 0.05) the DM (61 ± 0.4 g/LW^0.75/day) and organic matter (OM) intake (56 ± 0.7 g/LW^0.75/day). Total DM digestibility (68 ± 2.5%), OM (70 ± 3%), and NDF (60 ± 3%), were not different (P ≥ 0.05) between control and FPH inclusion diets. The diet had no effect on ruminal pH, ruminal ammonia concentration, total and individual volatile fatty acids. The chemical composition and sheep intake behavior indicate that FPH by‐product is medium quality forage when incorporated in maintenance rations.     

Replacement of Tifton hay by spineless cactus in Girolando post-weaned heifers´ diets

This study aims to evaluate the effect of the Tifton 85 hay (Cynodon dactylon L. Pers) replacement by Orelha de Elefante Mexicana spineless cactus (Opuntia stricta [Haw.] Haw) on the nutrient intake and digestibility, growth performance, microbial protein synthesis, and efficiency of dietary nitrogen compound utilization in the diets of Girolando heifers. Twenty-four (3.5 months and 100 kg ± 3.5 kg) Girolando heifers (5/8 Holstein x Gyr) were used and arranged in a completely randomized design. Dry matter, organic matter, crude protein, and neutral detergent fiber decreased linearly as a function of the levels of Tifton hay (TH) replacement by Orelha de Elefante Mexicana spineless cactus (OEM). The non-fiber carbohydrate intake and coefficient of dry matter digestibility increased, while the neutral detergent fiber (NDF) digestibility decreased linearly with the OEM inclusion. After evaluating the growth performance by observing weight gain and morphometric measurements, there were no significant alterations. The urinary volume, nitrogen balance as well as the efficiency of nitrogen retention had increased, while the urinary and plasma urea concentrations had decreased linearly with the OEM inclusion. The results obtained in this study show that Orelha de Elefante Mexicana spineless cactus should replace Tifton hay in post-weaned heifer diets.     

Effects of Bermudagrass hay and soybean hulls inclusion on performance of sheep fed cactus-based diets

The objective of this experiment was to determine the effects of replacing corn with soybean hulls (SH) or Bermudagrass tifton hay (TH) on performance of sheep fed cactus-based diets. Three ruminally fistulated sheep were used in a 3 × 3 Latin square experiment with 21-day periods. All diets contained 75% spineless cactus (dry matter basis, DM) and formulated to be isonitrogenous. Fiber source had no influence on nutrient intakes except for the intake of neutral detergent fiber (NDF) which was lower (p < 0.05) for animals fed corn relative to those fed SH or TH. Time expended in rumination and total chewing time were higher (p < 0.05) for animals fed TH than those fed SH or corn. In vivo nutrient digestibilities were similar for all dietary treatments and averaged 69.6%, 74.8%, 69.9%, and 61.8% for DM, organic matter, crude protein, and NDF, respectively. Feeding SH relative to TH and corn decreased ruminal pH (p < 0.05) and increased concentration of total volatile fatty acids (p < 0.05). However, ruminal NH₃–N concentration was higher (p < 0.05) for animal fed TH than for those fed SH or corn. Abdominal distension and ruminal biofilm production were greater (p < 0.05) in animals fed corn or SH than in those fed TH. It was concluded that replacing corn with SH or TH up to 15% of the diet DM in a cactus-based diet had no effect on nutrient intakes or total tract nutrient utilization. Changes in ruminal fermentation parameters reflected differences in ruminal degradability between the two fiber sources. Bermudagrass tifton hay was more effective than SH in reducing the risk of bloat associated with feeding high levels of spineless cactus to ruminants.     

Spineless cactus (Opuntia ficus-indica) and saltbush (Atriplex halimus L.) as feed supplements for fattening Awassi male lambs: effect on digestibility,water consumption,blood metabolites,and growth performance

The effect of replacing 13.6% and 20.3% of a total ration of fattening Awassi lambs by two combinations of fresh saltbush (Atriplex halimus) and fresh spineless cactus (Opuntia ficus-indica) cladodes at a ratio of 1.9:1 (TRT1) and 1.7:1 (TRT2) on water intake, digestibility, blood metabolites, and fattening performance was evaluated. Thirty-six lambs with average initial live weight 34.5?±?4.18 kg were randomly assigned to three diets (control, TRT1, and TRT2). The control received a diet containing 166 g/kg barley straw and 834 g/kg of commercial concentrate mixture; TRT1 comprised 126 g barley straw, 739 g/kg concentrate mixture, 47 g/kg spineless cactus, and 89 g saltbush; TRT2 comprised 67 g/kg barley straw, 704 g/kg commercial concentrate mixture, 86 g/kg spineless cactus, and 144 g saltbush. A growth trial of 100 days (10 days of adaptation and 90 days of collection) followed by a metabolism trial of 17 days (10 days of adaptation and 7 days of a total feces and urine collection) was carried out. Daily dry matter intake, digestibility of crude protein, ether extract and nutrient detergent fiber, nitrogen balance, average daily gain, feed conversion ratio, and blood metabolites were not significantly affected by the treatment. Water consumption in TRT2 was significantly 16% less compared with the control. A combination of saltbush and spineless cactus at a ratio of 1.7:1 (TRT2) replaced 60% of barley straw and 16% of concentrate mixture without adverse effects on health and growth performance of Awassi male lambs. This represents a potential reduction in feed costs for smallholder farmers.

     

Silage fermentation and ruminal degradation of stylo prepared with lactic acid bacteria and cellulase

In order to improve the silage fermentation of stylo (Stylosanthes guianensis ) in tropical areas, stylo silages were prepared with commercial additives Lactobacillus plantarum Chikuso‐1 (CH 1), L. rhamnasus Snow Lact L (SN ), Acremonium cellulase (CE ) and their combination as SN +CE or CH 1 + CE , and the fermentation quality, chemical composition and ruminal degradation of these silages were studied. Stylo silages treated with lactic acid bacteria (LAB ) or cellulase, the pH value and NH ₃‐N ? total‐N were significantly (P  <  0.05) decreased while the ruminal degradability of dry matter (DM ), crude protein (CP ), neutral detergent fiber (aNDF om) and acid detergent fiber (ADF om) were significantly (P  <  0.05) increased compared to control. Compared to LAB or cellulase‐treated silages, the DM , CP contents and relative feed value (RFV ), and the ruminal degradability in LAB plus cellulase‐treated silages were significantly (P  <  0.05) higher, but the aNDF om content was significantly (P  <  0.05) lower. CH 1 + CE treatment was more effective in silage fermentation and ruminal degradation than SN +CE treatment. The results confirmed that LAB or LAB plus cellulase treatment could improve the fermentation quality, chemical composition and ruminal degradation of stylo silage. Moreover, the combined treatment with LAB and cellulase may have beneficial synergistic effects on ruminal degradation.     

Tifton hay, soybean hulls, and whole cottonseed as fiber source in spineless cactus diets for sheep

The objective of this paper was to evaluate the effect of three different sources of fiber (tifton hay, soybean hulls, and whole cottonseed) in spineless cactus diets for sheep in the semiarid region of northeastern Brazil. Twenty-one sheep in finishing phase with indeterminate breed, non-castrated, and with initial weight of 18.90?±?1.07 kg were randomly distributed to individual stalls where they were confined for the duration of the experiment. The intakes of dry and organic matter, total carbohydrates, and total digestive nutrients were not influenced (P?>?0.10) by the different fiber sources (1.10, 0.97, 0.73, and 0.80 kg/day, respectively). However, sheep which received the whole cottonseed diet were characterized by a lower (P?<?0.10) intake of crude protein and neutral detergent fiber and greater (P?<?0.10) intake of ether extract (0.11, 0.29, and 0.048 kg/day, respectively). The different sources of fiber resulted in similar times spent feeding (P?>?0.10), although the rumination time was greater for tifton hay (P?<?0.10) (429.05 min/day). The digestibility coefficient of dry and organic matter differed between the treatments (P?<?0.10), with the soybean hull diet showing a higher level of digestion (83.23 and 86.72 %, respectively). The whole cottonseed diet gave the smallest digestibility coefficient of crude protein (68.95 %) and greatest for ether extract (85.94 %). The daily weight gain of animals fed on whole cottonseed was significantly lower (P?<?0.10). On the basis of these findings, we recommend the use of tifton hay or soybean hulls as important additional source of fiber in forage spineless cactus diets for sheep in finishing phase.     

Silages in the form of diet based on spineless cactus and buffelgrass

This study was conducted to evaluate the fermentation pattern and the in situ dry matter degradability of silages in the form of diet. Five diets were formulated based on spineless cactus (Opuntia fícus-indica cv. ‘Gigante’) and buffelgrass (Cenchrus ciliaris). The experimental design was completely randomised, with five treatments and three replicates in which the diets differed in the proportion of buffelgrass (0%, 15%, 25%, 30% and 35%, on a fresh matter basis). There was significant difference (p < 0.05) in the chemical composition of the diets, with all dry matter contents being within the ideal range. Ammonia-nitrogen content was not affected (p > 0.05). There were significant differences (p < 0.05) in dry matter recovery across diets, which ranged from 96.28% to 99.93%. The pH values decreased as the time of opening (days) was extended. Organic acid contents differed across all diets; however, overall, all diets showed satisfactory lactic acid contents. As the proportion of buffelgrass in the diets was increased, the degradability of dry matter decreased. Based on fermentation profile, losses and chemical composition the diet with higher proportion of spineless cactus can be recommended for silage production.     

Spineless cactus associated with Tifton hay or sugarcane bagasse may replace corn silage in sheep diets

The effect of the replacement of corn silage with spineless cactus associated with Tifton 85 hay or sugarcane bagasse was evaluated on the performance, body weight components and sheep meat quality. Twenty-one Santa Inês male sheep with initial body weight of 22.9 ± 2.9 kg were used. They were confined in individual stalls for 74 days receiving the following diets: corn silage + concentrate (CS); spineless cactus + Tifton 85 hay + concentrate (TH); spineless cactus + sugarcane bagasse + concentrate (SB). After the feedlot period, the animals were slaughtered and their body components were weighed and sampled. Data were submitted to Tukey’s test at 5% probability. The average daily gain (0.25 vs 0.14 kg), cold carcass weight (13.3 vs 13.7 kg), loin muscularity (0.6 vs 0.4 kg) and liver weight (0.7 vs. 0.5 kg) were higher (P < 0.05) for the TH diet when compared to that for the CS. The physical-chemical parameters of meat were not influenced (P > 0.05) by the treatments and presented about 20.1% of crude protein, 6.1% of crude fat and shear force of 2.0 kgf/cm². In complete diets for sheep, Tifton 85 hay associated with spineless cactus provides greater weight gain, cold carcass muscularity and organ weight when compared to those for animals fed with corn silage as exclusive roughage. Sugarcane bagasse associated with spineless cactus may replace corn silage in complete diets for sheep.     

Effect of spineless cactus intake (<Emphasis Type="Italic">Opuntia ficus-indica</Emphasis>) on blood glucose levels in lactating sows and its impact on feed intake,body weight loss,and weaning-estrus interval

The effect of spineless cactus intake (Opuntia ficus-indica) on blood glucose (BG) levels in lactating sows and its impact on daily and total feed intake (dFI^?1 and TFI, respectively), body weight loss (BWL), and weaning-estrus interval length (WEI) were evaluated. Thirty-four hybrid (Yorkshire × Landrace × Pietrain) sows in lactation phase were used. Sows were divided into two groups: G1 (n = 17) where they received commercial feed and G2 (n = 17) provided with commercial feed plus an average of 2.0 ± 0.5 kg spineless cactus, based on a sow’s body weight. The variables evaluated were BG, dFI^?1, TFI, BWL, and WEI. Statistical analysis was performed by using a fixed and mixed model methodology, under a repeated measurements experiment. Group effects were found on all analyzed variables (P < 0.05). The BG was lower in G2 (55.2 and 64.5 mg/dL pre- and post-prandial, respectively), compared to that in G1 (70.9 and 80.1 mg/dL pre- and post-prandial, respectively) (P < 0.05). G2 showed better performance than G1 for dFI^?1, BWL, and WEI (P < 0.05) whose averages were 5.5 ± 1.8 kg, 7.4 ± 4.5%, and 5.3 ± 1.2 days, respectively. Averages for these variables in G1 were 4.7 ± 1.5 kg, 16.8 ± 4.6%, and 6.1 ± 1.6 days, respectively. Intake of spineless cactus reduced BG levels in lactating sows, generating greater dFI^?1, lower BWL at the end of lactation, and a lower WEI.     

Research note: The silage characteristics of two varieties of forage sorghum mixed in different proportions and at two stages of maturity

Abstract

Two varieties of forage sorghum, low grain Dekalb FS‐5 (FS) and higher grain Pioneer 947 (GS) were harvested at the milk and dough stages of maturity respectively. Each variety was ensiled separately and as mixtures under laboratory conditions. The mixtures comprised FS.GS at ratios of 3:1 and 1:1 respectively. At the milk stage the FS had a dry matter (DM) content of 338 g kg^?1 and water‐soluble carbohydrates (WSC) content of 120 g kg^?1, as compared with 389 g kg^?1 and 63 g kg^?1, respectively for the GS. At the dough stage, these contents were 374 g kg^?1 and 123 g kg^?1 for the FS, and 520 g kg^?1 and 29 g kg^?1 for the GS, respectively. At the dough stage the GS had higher neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents than FS (592 g kg^?1 and 379 g kg^?1 vs. 533 g kg^?1 and 339 g kg^?1 DM, respectively). In the silage harvested at milk stage, the pH of FS alone decreased most slowly, whereas at the dough stage the pH of the GS remained highest. In mixtures the pH decline accelerated with an increasing proportion of FS. Following harvest at the milk stage the 3:1 (FS:GS) had the best ensiling characteristics, whereas following at the dough stage the 1:1 mixture provided the most stable silage. Rumen degradability of the silage of GS was higher than that of the FS silage, especially for material harvested at dough stage of maturity (59.2 g kg^?1 vs. 50.9 g kg^?1). Mixing FS with GS at the ensiling increased the digestibility of the resulting silage as compared with FS alone.     

Age and Body Condition of Goats Influence Consumption of Juniper and Monoterpene-Treated Feed

Redberry juniper (Juniperus pinchotii Sudworth) is an invasive, evergreen tree that is rapidly expanding throughout western and central Texas. Goats will consume some juniper on rangelands; however, intake is limited. The objective of our research was to determine how the age and body condition of goats influence their consumption of juniper and an artificial feed containing 4 monoterpenes. Two separate experiments were conducted. Experiment 1 examined the intake of redberry juniper foliage and used 39 goats either young (2 yr) or mature (> 6 yr). One-half of each age group was fed appropriate basal rations to reach either a high (HBC) or low body condition (LBC). Goats in LBC ate more (P < 0.01, 8.6 g · kg⁻¹ body weight [BW] ± 0.7 SE) juniper than those in HBC (2.3 g · kg⁻¹ BW ± 0.3 SE), and young animals consumed more (P < 0.05, 7.2 g · kg⁻¹ BW ± 0.7 SE) juniper than mature goats (3.9 g · kg⁻¹ BW ± 0.5 SE) across body condition treatments. In experiment 2, 36 goats, either young (2 yr) or mature (> 6 yr) and in either HBC or LBC, were offered a synthetic ration treated with 20.8 g · kg⁻¹ of 4 monoterpenes found in redberry juniper. Goats in LBC ate more (P < 0.01, 25.3 g · kg⁻¹ BW ± 1.0 SE) of the terpene-treated feed than those in HBC (17.5 g · kg⁻¹ BW ± 0.7 SE), and young animals ate more (P < 0.05, 22.5 g · kg⁻¹ BW ± 0.8 SE) than mature goats (20.3 g · kg⁻¹ BW ± 0.8 SE) across body condition treatments. Total intake as a proportion of body weight was also affected by body condition. Age and body condition are important factors that influence intake of chemically defended plants. A better understanding of how these attributes affect diet selection will aid livestock producers in improving grazing management.     

Effects of species and season on chemical composition and ruminal crude protein and organic matter degradability of some multi-purpose tree species by West African dwarf rams

Seasonal chemical composition and ruminal organic matter (OM) and crude protein (CP) degradabilities were determined in four tropical multi-purpose tree species (MPTS) namely; Pterocarpus santalinoides, Grewia pubescens, Enterolobium cyclocarpum and Leucaena leucocephala. Three West African dwarf (WAD) rams fitted with permanent rumen cannula were used for the degradability trials. Foliage samples were collected four times to represent seasonal variations as follows: January--mid dry; April--late dry; July--mid rainy and October--late rainy seasons. Leaf samples were randomly collected from the trees for estimation of dry matter (DM) and chemical composition. Ruminal in sacco OM and CP degradabilities were estimated from residues in nylon bags. All samples had high CP (161-259 g/kg DM) and moderate fibre concentrations [neutral detergent fibre (without residual ash], 300-501 g/kg DM; acid detergent fibre (without residual ash), 225-409 g/kg DM and acid detergent lignin, 87-179 g/kg DM across seasons. Interaction effects of species and season on chemical composition were highly significant (p = 0.001) except for trypsin inhibitor (p = 0.614). The MPTS recorded more than 60% OM and CP degradability at 24 h, which implied that they were all highly degradable in the rumen. Their incorporation into ruminant feeding systems as dry season forage supplements is therefore recommended.     

Spineless cactus as a replacement for sugarcane in the diets of finishing lambs

The effects of replacement of sugarcane by spineless cactus (0, 33, 66, and 100 % on dry matter (DM) basis) were evaluated on intake, digestibility of nutrients, ingestive behavior, and performance of finishing lambs. Thirty-six non-castrated Santa Ines lambs at 4 months of age and an initial body weight of 22?±?2.3 kg were assigned in a randomized block design. A quadratic effect was found for intake of DM, organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), and digestible organic matter (DOM), with maximum values of 1.31, 1.19, 0.219, 0.358, and 0.845 g/day estimated with 42.5, 38.5, 38.8, 21.3, and 44.9 % replacement level, respectively. The digestibility of DM, OM, CP, and EE increased linearly; however, there was a quadratic effect on NDF digestibility with maximum value estimated of 500 g/kg with 64.2 % replacement level. Rumination time, total chewing, and rumination efficiency decreased linearly with the replacement levels; however, idle time increased linearly. A quadratic effect was found for final weight, body weight gain, and total weight gain with maximum values estimated of 38.6 kg, 0.232 kg/day, and 16.2 kg with 39.1, 38.2, and 40.4 % replacing levels. The replacement of 49.5 % sugarcane by spineless cactus can be recommended as optimal level, and problems related to intake, digestibility, and performance are concentrated outside that level.     

微生态制剂对玉米秸秆青贮发酵品质、营养成分及瘤胃降解率的影响

本研究以玉米秸秆为研究对象,探讨酶制剂、菌制剂以及酶制剂与菌制剂混合处理对玉米秸秆青贮料发酵品质、营养成分以及瘤胃降解率的影响。玉米秸秆(干物质含量为42%~44%)用青贮切碎机切短至2 cm,将各处理青贮剂溶于蒸馏水,与原料混合均匀后,装入聚乙烯袋(24 cm×40 cm)中,每袋1 kg,然后用真空包装机抽真空封口,室温贮藏45 d后开封取样。采用实验室化学分析法及半体内试验测定发酵品质、营养成分和瘤胃降解率。结果表明,1)与对照组相比,菌制剂(LAB₁ 和LAB₂)处理组pH值和NH₃-N含量均显著降低(P<0.05),乳酸(LA)含量、有机物(OM)及可溶性碳水化合物(WSC)保存量、干物质(DM)、OM、粗蛋白(CP)的瘤胃降解率显著增加(P<0.05);菌制剂处理组的WSC含量显著高于对照组和酶制剂处理(P<0.05)。2)与对照组相比,酶制剂(CE₁和CE₂)处理组pH值、NH₃-N含量、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、纤维素均显著降低(P<0.05),乳酸(LA)含量、有机物(OM)及可溶性碳水化合物(WSC)保存量、干物质(DM)、OM、粗蛋白(CP)的瘤胃降解率显著增加(P<0.05);有降低酸性洗涤木质素(ADL)含量的趋势,但是差异不显著(P>0.05)。3)酶菌复合处理组(MCL₁和MCL₂)pH值最低(P<0.05),NDF、纤维素在瘤胃中降解能力显著高于其他处理组(P<0.05),ADL降解率在数值上高于其他组,但差异不显著(P>0.05);与对照组相比,酶菌混合处理组能够降低NDF、ADF、纤维素含量(P<0.05)。综上,酶菌复合添加剂喷洒到秸秆中进行青贮发酵后,能够有效破除玉米秸秆青贮饲料的特殊的木质素-纤维素-半纤维素复合体结构,改善秸秆青贮饲料的发酵品质,提高营养物质的保存量及反刍动物瘤胃对秸秆营养物质的降解率,从而提高秸秆的可利用率,其中MCL₂处理组效果最佳。     

苎麻营养成分分析及瘤胃降解特性研究

为系统的研究苎麻的营养价值及其在山羊瘤胃中的降解特性,利用化学分析等方法检测了7个茬次苎麻的粗蛋白(CP)、氨基酸(AA)组成、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)等营养成分、单宁等抗营养成分的含量,并采用3只装有永久瘤胃瘘管的波尔山羊为试验动物,对苎麻的部分营养成分的降解率和降解参数进行测定。结果表明,7个茬次苎麻的CP含量均较高且品质较好,CP平均值达到了19.57%,而且呈现出随着茬次的增加,CP含量有所下降的趋势,但是第7茬和第6茬相比CP含量略有升高。AA总和平均值达到了16.40%,占CP平均值含量的83.80%,赖氨酸(Lys)的平均含量达到了0.84%,苏氨酸(Thr)的平均含量达到了0.82%。抗营养因子方面,单宁可能是苎麻最主要的抗营养因子,平均值达到了0.67%。苎麻的干物质(DM)、CP、有机物(OM)、NDF和ADF的降解率均随着瘤胃消化时间的延长而不断提高,有效降解率分别达到了47.00%,35.53%,44.29%,57.68%和38.59%。由此得出,苎麻的营养价值较高,主要体现在CP含量高且品质较好,主要营养成分的瘤胃降解率均较高,可以作为反刍动物优良的粗饲料资源加以开发利用。     

Effects of dietary protein levels and 2‐methylbutyrate on ruminal fermentation,nutrient degradability,bacterial populations and urinary purine derivatives in Simmental steers

The objective of this study was to evaluate the effects of dietary crude protein (CP ) levels and 2‐methylbutyrate (MB ) supplementation on ruminal fermentation, bacterial populations, microbial enzyme activity and urinary excretion of purine derivatives (PD ) in Simmental steers. Eight ruminally cannulated Simmental steers, averaging 18 months of age and 465 ± 8.6 kg of body weight (BW ), were used in a replicated 4 × 4 Latin square design by a 2 × 2 factorial arrangement. Low protein (98.5 g CP /kg dry matter [LP ] or high protein (128.7 g CP /kg dry matter [HP ]) diets were fed with MB supplementation (0 g [MB ?] or 16.8 g steer^?1 day^?1 [MB +]). Steers were fed a total mixed ration with dietary corn straw to concentrate ratio of 50:50 (dry matter [DM ] basis). The CP  × MB interaction was observed for ruminal total VFA , molar proportions of acetate and propionate, acetate to propionate ratio, ammonia‐N, effective degradability of neutral detergent fibre (NDF ) and CP , microbial enzyme activity, bacterial populations and total PD excretion (p  < .05). Ruminal pH decreased (p  < .05), but ruminal total VFA concentration increased (p  < .05) with increasing dietary CP level or MB supplementation. Acetate molar proportion increased (p  = .043) with MB supplementation, but was not affected by dietary CP level. Propionate molar proportion decreased (p  < .05) with increasing dietary CP level or MB supplementation. Consequently, acetate‐to‐propionate ratio increased (p  = .001) with MB supplementation, but was not affected by dietary CP level. Ruminal ammonia‐N content increased (p  = .034) with increasing dietary CP level, but decreased (p  = .012) with MB supplementation. The effective degradability of NDF and CP increased (p  < .05) with increasing dietary CP level or MB supplementation. Microbial enzyme activity, bacterial populations and total PD excretion also increased (p  < .05) with increasing dietary CP level or MB supplementation. The results indicated that ruminal fermentation, nutrient degradability, microbial enzyme activity, ruminal bacterial populations and microbial protein synthesis improved with increasing dietary CP level or MB supplementation in steers.     

Chemical composition,nitrogen degradability and in vitro ruminal biological activity of tannins in vines harvested from four tropical sweet potato (Ipomoea batatas L.) varieties

This study investigated the potential of vines from four sweet potato varieties (Tia Nong 57, Tia Nong 66, Ligwalagwala and Kenya) as alternative feed resources for ruminant livestock. The chemical composition [neutral detergent fibre (NDF), acid detergent fibre (ADF), crude protein (CP) and acid detergent insoluble nitrogen (ADIN)], in vitro ruminal nitrogen (N) degradability and in vitro ruminal biological activity of tannins in the vines, harvested at 70 and 110 days after planting (DAP), were determined. Variety and harvesting stage did not (p > 0.05) influence CP and NDF content of the vines. Concentration of CP ranged from 104.9 to 212.2 g/kg DM, while NDF ranged from 439.4 to 529.2 g/kg DM across harvesting stages and varieties. Nitrogen degradability (ND) at 70 and 110 DAP was highest (p < 0.05) in Ligwalagwala (743.1 and 985.0 g/kg DM, respectively). Treatment of vines with tannin‐binding polyethylene glycol (PEG) increased (p < 0.05) in vitro ruminal cumulative gas production parameters (a, b and c). The in vitro ruminal biological activity of tannins, as measured by increment in gas production parameters upon PEG inclusion, had a maximum value of 18.2%, suggesting low to moderate antinutritional tannin activity. Ligwalagwala vines, with highly degradable N, would be the best protein supplement to use during the dry season when ruminant animals consume low N basal diets and maintenance is an acceptable production objective. Tia Nong 66 and Kenya varieties, with less degradable N, may be more suitable for use as supplements for high‐producing animals such as dairy goats.     

Does the level of forage neutral detergent fiber affect the ruminal fermentation,digestibility and feeding behavior of goats fed cactus pear?

This study aimed to evaluate the effects of forage neutral detergent fiber (fNDF) levels on the voluntary feed intake, digestibility, ruminal fermentation and feeding behavior of goats fed diets with cactus pear. Five non‐lactating ruminally cannulated goats fed ad libitum were randomly assigned to a 5 × 5 Latin square design. Treatments consisted of levels of fNDF at 0, 109, 222, 339 and 463 g/kg of dry matter (DM) in cactus pear‐based diets. The intakes of DM and NDF were quadratically affected (p ≦ .045) by fNDF levels. Voluntary water intake (VWI) increased linearly as the fNDF levels increased in the diet. The digestibility coefficients of organic matter, NDF and ether extract and total digestible nutrients concentration were quadratically affected (p ≦ .048) by fNDF levels. The ruminal pH linearly increased (p = .001) with fNDF levels, ranging from 5.44 to 5.81 for diets containing 0 and 463 g fNDF/kg DM, respectively. The fNDF levels promoted a linear increase (p = .006) in chewing time, linearly decreased (p = .007) resting time and quadratically affected (p = .033) rumination time. The inclusion of fNDF in the diets provided favorable conditions for ruminal function, digestibility and feeding behavior in goats fed diets containing cactus pear.     

Effects of concentrate‐to‐forage ratios and 2‐methylbutyrate supplementation on ruminal fermentation,bacteria abundance and urinary excretion of purine derivatives in Chinese Simmental steers

This study evaluated the effects of dietary concentrate levels and 2‐methylbutyrate (2MB ) supplementation on performance, ruminal fermentation, bacteria abundance, microbial enzyme activity and urinary excretion of purine derivatives (PD ) in steers. Eight ruminally cannulated Simmental steers (12 months of age; 389 ± 3.7 kg of body weight) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement. Moderate‐concentrate (400 g/kg diet [MC ]) or high‐concentrate (600 g/kg diet [HC ]) diets were fed with or without 2MB (0 g/day [2MB ?] or 15.0 g/day [2MB +]). Dry matter intake and average daily gain increased, but feed conversion ratio decreased with the HC diet or 2MB supplementation. Ruminal pH decreased, but total volatile fatty acid increased with the HC diet or 2MB supplementation. Molar proportion of acetate and acetate‐to‐propionate ratio decreased with the HC diet, but increased with 2MB supplementation. Propionate molar proportion and ruminal NH ₃‐N content increased with the HC diet, but decreased with 2MB supplementation. Neutral detergent fibre degradability decreased with the HC diet, but increased with 2MB supplementation. Crude protein degradability increased with the HC diet or 2MB supplementation. Abundance of Ruminococcus albus , Ruminococcus flavefaciens , Fibrobacter succinogenes and Bufyrivibrio fibrisolvens as well as activities of carboxymethyl cellulase, cellobiase, xylanase and pectinase decreased with the HC diet, but increased with 2MB supplementation. However, abundance of Prevotella ruminicola and Ruminobacter amylophilus as well as activities of α‐amylase and protease increased with the HC diet or 2MB supplementation. Total PD excretion also increased with the HC diet or 2MB supplementation. The results suggested that growth performance, ruminal fermentation, CP degradability and total PD excretion increased with increasing dietary concentrate level from 40% to 60% or 2MB supplementation. The observed diet × 2MB interaction indicated that supplementation of 2MB was more efficacious for improving growth performance, ruminal fermentation and total PD excretion with promoted ruminal bacteria abundance and enzyme activity in the MC diet than in the HC diet.