Effects of wheat straw particle size as a free-choice provision on growth performance and feeding behaviors of dairy calves

In the dairy calf feeding, supplementation of forage to the starter feed is commonly practiced. However, data are insufficient about how changes in particle size (PS) of forage affect calf performance and behavior in a free-choice forage provision system. This study aimed to assess the effects of supplementing wheat straw varying in PS on performance, skeletal growth characteristics, ruminal pH, nutritional behaviors, and blood metabolites of dairy calves. Forty-eight Holstein calves (43.8 ± 3.2 kg of BW) from d 15 of age were randomly assigned to one of the four treatments (n = 12/treatment; six males and six females): (1) starter without wheat straw supplementation (CON), (2) CON supplemented with wheat straw chopped at 1 mm geometrical mean particle length (GMPL) (fine PS), (3) CON supplemented with wheat straw at 4 mm GMPL (medium PS), and (4) CON supplemented with wheat straw at 7 mm GMPL (long PS). The calves were given ad libitum access to feed and water throughout the study. All calves were weaned on d 56 of age and continued the experiment until d 90. The starter, wheat straw, and total solid feed intakes were not affected by GMPL of wheat straw; however, CON calves had a lower solid feed-, total DM- and NDF-intake than calves offered wheat straw. Further, ADG, weaning, and final BWs as well as feed efficiency were similar between treatments. No difference was observed in growth rate of hip height, hip width, body barrel, wither height, and heart girth among treatments, however, wheat straw supplemented calves tended to have greater body length at weaning. Blood concentration of serum β-hydroxy butyrate was greater in wheat straw supplemented calves compared with CON calves on d 56 and 90. Calves supplemented with wheat straw spent more time eating starter and forage, lying and ruminating and less time for standing and non-nutritional behaviors compared with the CON calves on d 49 and 63 of the study. Moreover, calves offered wheat straw had greater ruminal pH than CON calves at 4 and 8 h after offering starter feed on d 35. In conclusion, supplementing wheat straw as a free-choice increased solid feed intake, rumen pH, and calves' welfare, however, PS of wheat straw had no effect.     

Effects of grain type and conditioning temperature during pelleting on growth performance,ruminal fermentation,meat quality and blood metabolites of fattening lambs

Ruminants can tolerate moderate concentrations of dietary tannin, making it feasible to replace corn with sorghum in ruminant diets; however, conditioning temperature of pelleted total mixed ration (PTMR) greatly affects nutrient digestibility. The objective was to determine effects of grain type and conditioning temperature during pelleting on growth performance, ruminal fermentation, meat quality and blood metabolites of fattening lambs. This was a 2 × 3 factorial study, with corn and sorghum and three conditioning temperatures (65, 75 and 85 °C) in a randomized complete design, with 36 lambs (120 ± 10.2 d and 24.9 ± 3.3 kg) grouped by weight and randomly allocated. The resulting six PTMRs were referred to as 65-S, 75-S and 85-S for sorghum-based diets, and 65-C, 75-C and 85-C for corn-based diets, for low, medium and high pelleting temperatures, respectively. There was no grain type × conditioning temperature (Grain × Temp) interaction on growth performance and apparent nutrient digestibility. Furthermore, grain type did not affect DM intake (DMI), average daily gain (ADG) or feed conversion ratio (FCR) of fattening lambs. Pelleting at 75 °C improved ADG (P < 0.03) and FCR (P < 0.02) of fattening lambs compared to other temperatures. There was a Grain × Temp interaction (P < 0.01) on ruminal pH (lowest in lambs fed 75-S). There tended (P = 0.07) to be a Grain × Temp interaction for total volatile fatty acid (VFA), and there were Grain × Temp interactions for molar proportions of acetate (P < 0.04), butyrate (P < 0.03) and branch-chained VFA (P < 0.01). Lambs fed sorghum-based PTMR had greater molar proportion of propionate (P < 0.03) and lower acetate to propionate ratio (A:P, P < 0.04). Lambs fed sorghum-based PTMR had higher plasma concentrations of urea nitrogen (N) (P < 0.03), glucose (P < 0.01) and alkaline phosphatase (P < 0.05), whereas other blood metabolites were not affected by treatments. There were Grain × Temp (P < 0.03) interactions for color coordinates of longissimus and mid-gluteal muscle. Lambs fed sorghum-based PTMR had lower (P < 0.01) dressing percentage and meat quality than those fed corn-based PTMR. We concluded that sorghum can replace corn in lamb diets without compromising growth performance and feed efficiency; furthermore, feeding sorghum vs corn improved rumen fermentation, with reduced A:P ratio and enhanced N and glucose utilization. Finally, pelleting at 75 °C increased feeding value of either sorghum- or corn-based PTMR for fattening lambs.     

Common vetch varietal differences in hay nutritive value,ruminal fermentation,nutrient digestibility and performance of fattening lambs

In some lower rainfall regions of the world (300–750 mm), common vetch (Vicia sativa L., hereafter referred to as vetch) has been shown to have yields competitive with alternate crops and provide high-quality hay for ruminant diets, but there are few studies of vetch performance as a livestock feed, or of vetch varietal differences in livestock feeding value. This study evaluated vetch varietal differences in hay nutritive value, ruminal fermentation properties, nutrient digestibility, nitrogen retention and animal performance in fattening lambs consuming a diet comprising 20% vetch. Fifty male Hu lambs with an initial BW of 17.7 ± 0.27 kg and 2–3 months of age were assigned randomly into five groups of 10 lambs, and each allocated one of five dietary treatments for 67 days (10 days of adaptation and a 57 day experimental period). All diets contained 30% maize stover, 50% concentrate, and with a different forage source (on an as-fed basis): 20% alfalfa hay (Control), 20% vetch 333A (C333A) hay, 20% vetch Lanjian No. 1 (CLJ1) hay, 20% vetch Lanjian No. 2 (CLJ2) hay, or 20% vetch Lanjian No. 3 (CLJ3) hay. Hay CLJ3 had greater contents of ash, CP, ether extract, in vitro organic matter digestibility and metabolizable energy, and lower cell wall contents (P < 0.05) than those of C333A and CLJ1 hays, but similar to the CLJ2 hay (P > 0.05). Compared to the Control diet, the CLJ2 and CLJ3 diets resulted in greater (P < 0.05) final BW, average daily gain, total tract apparent digestibility of CP and NDF, and nitrogen balance, both when expressed as g/day and relative to nitrogen intake, while animal performance when fed diets with C333A or CLJ1 diet did not differ (P > 0.05) from the Control diet. No differences (P > 0.05) were observed between dietary treatments with respect to average daily feed intake, ruminal pH, total volatile fatty acid contents and molar proportions of acetate, butyrate, valerate, isobutyrate, and isovalerate, or total tract apparent digestibility of DM, organic matter, and ADF. The feed efficiency of tested feeds ranked CLJ3 = CLJ2 > CLJ1 > Control with C333A intermediate between CLJ1 and Control. In summary, considering hay quality, nutrient digestibility and animal weight gain, performance as a ruminant feed of hays from recently released vetch cultivars Lanjian No. 2 and Lanjian No. 3 was superior to the older cultivar C333A and the alfalfa control.     

Effects of different sources of physically effective fiber on rumen microbial populations

Physically effective fiber is needed by dairy cattle to prevent ruminal acidosis. This study aimed to examine the effects of different sources of physically effective fiber on the populations of fibrolytic bacteria and methanogens. Five ruminally cannulated Holstein cows were each fed five diets differing in physically effective fiber sources over 15 weeks (21 days/period) in a Latin Square design: (1) 44.1% corn silage, (2) 34.0% corn silage plus 11.5% alfalfa hay, (3) 34.0% corn silage plus 5.1% wheat straw, (4) 36.1% corn silage plus 10.1% wheat straw, and (5) 34.0% corn silage plus 5.5% corn stover. The impact of the physically effective fiber sources on total bacteria and archaea were examined using denaturing gradient gel electrophoresis. Specific real-time PCR assays were used to quantify total bacteria, total archaea, the genus Butyrivibrio, Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens and three uncultured rumen bacteria that were identified from adhering ruminal fractions in a previous study. No significant differences were observed among the different sources of physical effective fiber with respect to the microbial populations quantified. Any of the physically effective fiber sources may be fed to dairy cattle without negative impact on the ruminal microbial community.     

Effects of an artificial hay aroma and compound feed formulation on feed intake pattern,rumen function and milk production in lactating dairy cows

The Kempen system is a dairy feeding system in which diet is provided in the form of a compound feed (CF) and hay offered ad libitum. Ad libitum access to CF and hay allows cows in this system to achieve a high DM intake (DMI). Out of physiological concerns, the voluntary hay intake could be increased and the consumption pattern of CF could be manipulated to maintain proper rumen functioning and health. This study investigated the effects of an artificial hay aroma and CF formulation on feed intake pattern, rumen function and milk production in mid- to late-lactating dairy cows. Twenty Holstein–Friesian cows were assigned to four treatments in a 4 × 4 Latin square design. Diet consisted of CF and grass hay (GH), fed separately, and both offered ad libitum, although CF supply was restricted in maximum meal size and speed of supply by an electronic system. Treatments were the combination of two CF formulations – high in starch (CHS) and fibre (CHF); and two GH – untreated (UGH) and the same hay treated with an artificial aroma (TGH). Meal criteria were determined using three-population Gaussian–Gaussian–Weibull density functions. No GH × CF interaction effects on feed intake pattern characteristics were found. Total DMI and CF intake, but not GH intake, were greater (P < 0.01) in TGH treatment, and feed intake was not affected by type of CF. Total visits to feeders per day, visits to the GH feeder, visits to the CF feeder and CF eating time (all P < 0.01) were significantly greater in cows fed with TGH. Meal frequency, meal size and meal duration were unaffected by treatments. Cows fed CHF had a greater milk fat (P = 0.02), milk urea content (P < 0.01) and a greater milk fat yield (P < 0.01). Cows fed TGH had a greater milk lactose content and lactose yield (P < 0.05), and milk urea content (P < 0.01). Cows fed TGH had smaller molar proportions of acetic acid and greater molar proportions of propionic acid compared with UGH. In conclusion, treatment of GH with an artificial aroma increased CF intake and total DMI, but did not affect hay intake. Additionally, GH treatment increased the frequency of visits to both feeders, and affected rumen volatile fatty acid profile. Type of CF did not affect meal patterns, ruminal pH, nor fermentation profiles.     

Cashew nut meal as feed supplement for lambs

Cashew nut meal (CNM) is widely used in tropical countries due to the high protein and energy levels; therefore, it has potential to be an alternative feed supplementation for livestock. Our objective was to evaluate the use of CNM as feed supplement for lambs. Twenty-four lambs were divided into a randomized block design with four treatments, starting with a diet control of Tifton 85 (Cynodon spp.) hay and CNM as a supplement at three different levels representing 6, 12, and 18% of the total mixed ration (TMR) provided. There were evaluated intake (g/day and g/kgBW^0.75); the digestibility of DM and nutrients; nitrogen balance; and ingestive behavior. The CP and ether extract (EE) intake (g/day) as well as DM, and organic matter (OM) intake (g/kgBW^0.75) were influenced by supplementation with CNM in a positive linear increase (P < 0.05). The digestibility of DM, OM and NDF increased according to the levels of CNM up to 12% and markedly decreased at the higher level (P < 0.05). The EE and CP digestibility raised according to the CNM levels (P < 0.05) and consequently increased the nitrogen retention resulting in a positive nitrogen balance. The protein and energetic characteristics of CNM show that it can be used as an alternative supplementation to low-quality forages for lambs. However, its use as a single supplement ingredient above 7% on total mixed ration may reduce fiber digestibility.     

Effect of wilting and the additives,straw, molasses and urea on the fermentation pattern of maize silage

The process of ensiling was studied in fresh maize (15% dry matter (DM)), wilted maize (18 and 24% DM) and maize mixed with 5–20% of wheat straw (18, 25 and 29% DM). Silages with 24% DM were preserved better than those with lower dry matter content. There was a significant change, with time, in pH, titrable acidity, volatile fatty acids, lactic acid, number of lactic acid bacteria, volatile nitrogen and soluble sugars in all the treatments. There was a significant decline in volatile fatty acids (P<0.05) and ammonia (P<0.01) production, and a significant increase in soluble sugar (P<0.01) in silages made after wilting. A significant decline in titrable acidity (P<0.01), volatile fatty acid production (p<0.05) and ammonia nitrogen (P<0.01), and a significant increase in pH (P<0.01) were found in silages of maize mixed with wheat straw. The overall rate of fermentation decreased during the first few days of fermentation in wilted and wheat straw silages, but the final products had characteristics of a good silage. In the second experiment the effect of urea and molasses was studied on wheat straw plus maize (15:85) silage with an initial DM content of 31–34%. Three levels of molasses (0, 3 and 6% of fresh weight) and two levels of urea (0 and 0.5% of fresh weight) were studied. Urea treatment with 3% molasses was found to be the best on the basis of silage characteristics.     

Comparison of the behaviour of Awassi lambs in cafeteria feeding system with single diet feeding system

This study was carried out to compare behavioural activities of Awassi lambs in cafeteria feeding system with conventional feeding (control) that animals fed concentrate. Sixteen, 3-month-old male lambs were housed individually for 42 days. The main effect was on the feeding systems, cafeteria and control. Cafeteria lambs (n=8) were offered the main ingredients (barley, cotton seed meal (CSM), wheat bran and alfalfa straw), while control animals (n=8) were fed a single diet (48% barley, 22% cottonseed meal, 18% wheat bran, 10% alfalfa and 2% vitamin–mineral mixture; having 2467 Kcal ME and 161 g kg⁻¹) with the same main ingredients with slightly higher nutrient content for growth. Food and water intakes were recorded daily, while behavioural observations were recorded twice a week for a period of 1 h at 5 min intervals at 13:00, 16:00, 19:00, 22:00, 01:00, 04:00, 07:00 and 10:00 h after the initiation of daily feeding. After every 5 min, each lamb was monitored to determine its eating, ruminating, drinking, walking, standing, playing, resting and other activities.Cafeteria lambs selected a diet that matched their growth requirement as did control lambs. However, cafeteria lambs ate more (P<0.01). Cafeteria animals preferred cotton seed meal (42.4%) to barley (32.9%) without changing their water intake, final live weight and daily gain (P>0.05). Cafeteria lambs also had higher rates of eating (22% versus 19%, P<0.01), ruminating (24% versus 23%, P>0.05) and resting (29% versus 23%, P<0.01) than the control lambs. On the other hand, cafeteria lambs spent less time standing (19% versus 25%, P<0.01) and walking (1.5% versus 2.1%, P<0.01) compared with control animals. In conclusion, cafeteria lambs selected a diet that matched their presumed biological (behavioral and nutritional) needs without changing their growth performance.     

Garlic skin induces shifts in the rumen microbiome and metabolome of fattening lambs

Garlic (Allium sativum L.) and its constituents have been shown to modify rumen fermentation and improve growth performance. Garlic skin, a by-product of garlic processing, contains similar bioactive components as garlic bulb. This study aimed to investigate the effects of garlic skin supplementation on growth performance, ruminal microbes, and metabolites in ruminants. Twelve Hu lambs were randomly assigned to receive a basal diet (CON) or a basal diet supplemented with 80 g/kg DM of garlic skin (GAS). The experiment lasted for 10 weeks, with the first 2 weeks serving as the adaptation period. The results revealed that the average daily gain and volatile fatty acid concentration were higher (P < 0.05) in lambs fed GAS than those in the CON group. Garlic skin supplementation did not significantly (P > 0.10) affect the α-diversity indices, including the Chao1 index, the abundance-based coverage estimator value, and the Shannon and Simpson indices. At the genus level, garlic skin supplementation altered the ruminal bacterial composition by increasing (P < 0.05) the relative abundances of Prevotella, Bulleidia, Howardella, and Methanosphaera and decreasing (P < 0.05) the abundance of Fretibacterium. Concentrations of 139 metabolites significantly differed (P < 0.05) between the GAS and the CON groups. Among them, substrates for rumen microbial protein synthesis were enriched in the GAS group. The pathways of pyrimidine metabolism, purine metabolism, and vitamin B6 metabolism were influenced (P < 0.05) by garlic skin supplementation. Integrated correlation analysis also provided a link between the significantly altered rumen microbiota and metabolites. Thus, supplementation of garlic skin improved the growth performance of lambs by modifying rumen fermentation through shifts in the rumen microbiome and metabolome.     

Performance, chewing activity, and ruminal parameters in yearling beef steers fed early-harvested sorghum silage: Effect of chop length and wheat straw addition

Two experiments were conducted to evaluate effects of silage chop length (SCL) and long wheat straw (WS) addition on performance, ruminal parameters, and chewing activity of yearling beef steers. The aim of the first experiment was to measure dry matter (DM) intake, average daily gain (ADG) and feed conversion (FC). For this, 59 Angus yearling steers were assigned to one of the four treatments in a 2 × 2 factorial arrangement. The factors were SCL (i.e., 5.8 and 9.4 mm mean particle length, MPL) and WS addition (i.e., 0 and 100 g/kg). Diets consisted of 792 g/kg of early-harvested sorghum silage (SS, Sorghum bicolor (L.) Moench.), 200 g/kg of pelleted sunflower meal, and 8 g/kg of urea and mineral–vitamin supplements. The amount of SS was reduced by 100 g/kg when WS was added to the diet. The second experiment, which aimed to evaluate ruminal parameters and chewing activity, consisted of two treatments with four rumen-cannulated steers fed with a diet comprised of finely chopped SS (5.8 mm MPL) either with or without WS. In the first experiment, SCL had no effect on DM intake, ADG or FC, while addition of WS depressed DM intake and ADG and had a negative effect on FC, without interactions between the factors. In the second experiment, WS addition reduced DM intake and volatile fatty acid concentration, but did not affect rumen pH or chewing activity. Results suggest that WS addition to these SS-based diets containing a high aNDF did not improve the ruminal environment, did not affect chewing activity and had a negative effect on steer performance, while SCL may not affect performance of beef steers.     

Effects of guanidinoacetic acid supplementation on growth performance,nutrient digestion,rumen fermentation and blood metabolites in Angus bulls

Guanidinoacetic acid (GAA) can improve the growth performance of bulls. This study investigated the influences of GAA addition on growth, nutrient digestion, ruminal fermentation and serum metabolites in bulls. Forty-eight Angus bulls were randomly allocated to experimental treatments, that is, control, low-GAA (LGAA), medium-GAA (MGAA) and high-GAA (HGAA), with GAA supplementation at 0, 0.3, 0.6 and 0.9 g/kg DM, respectively. Bulls were fed a basal diet containing 500 g/kg DM concentrate and 500 g/kg DM roughage. The experimental period was 104 days, with 14 days for adaptation and 90 days for data collection. Bulls in the MGAA and HGAA groups had higher DM intake and average daily gain than bulls in the LGAA and control groups. The feed conversion ratio was lowest in MGAA and highest in the control. Bulls receiving 0.9 g/kg DM GAA addition had higher digestibility of DM, organic matter, NDF and ADF than bulls in other groups. The digestibility of CP was higher for HGAA than for LGAA and control. The ruminal pH was lower for MGAA, and the total volatile fatty acid concentration was greater for MGAA and HGAA than for the control. The acetate proportion and acetate-to-propionate ratio were lower for MGAA than for LGAA and control. The propionate proportion was higher for MGAA than for control. Bulls receiving GAA addition showed decreased ruminal ammonia N. Bulls in MGAA and HGAA had higher cellobiase, pectinase and protease activities and Butyrivibrio fibrisolvens, Prevotella ruminicola and Ruminobacter amylophilus populations than bulls in LGAA and control. However, the total protozoan population was lower for MGAA and HGAA than for LGAA and control. The total bacterial and Ruminococcus flavefaciens populations increased with GAA addition. The blood level of creatine was higher for HGAA, and the activity of l-arginine glycine amidine transferase was lower for MGAA and HGAA, than for control. The blood activity of guanidine acetate N-methyltransferase and the level of folate decreased in the GAA addition groups. The results indicated that dietary addition of 0.6 or 0.9 g/kg DM GAA improved growth performance, nutrient digestion and ruminal fermentation in bulls.     

Source of Copper May Have Regressive Effects on Serum Cholesterol and Urea Nitrogen Among Male Fattening Lambs

An experiment was conducted to determine the effect of dietary copper (Cu) on mineral profile, hematological parameters, and lipid metabolism in lambs. Eighteen Zandi male lambs (approximately 3 months of age; 17.53?±?1.6 kg of body weight) were housed in individual pens and were assigned randomly to one of three treatments. Treatments consisted of (1) control (no supplemental Cu), (2) 10 mg Cu/kg dry matter (DM) from copper sulfate (CuS), and (3) 10 mg Cu/kg DM from Cu proteinate (CuP). The Cu concentration was 8.2 mg/kg DM in the basal diet. Blood was sampled from the jugular vein at the beginning of the study (enrollment, before feeding Cu supplement) and at days 25, 50, and 70 of experiment. The amounts of total serum glucose, urea nitrogen, calcium, phosphorus, iron, copper, zinc, and lipids and hematological parameters were measured. Average daily gain and feed efficiency were improved (P?<?0.05) with Cu supplementation and were better for the lambs fed diet supplemented with CuP. The concentrations of serum Ca, P, and Zn were not affected by source of Cu in the diet. However, Fe concentration was lower (P?<?0.01) in the Cu-supplemented groups. Experimental treatment had no significant effects on the hematological parameters. The serum glucose concentration was not affected by treatments. However, the urea nitrogen concentrations were significantly affected (P?<?0.05) by added Cu and was lower for CuP group as compared to the lambs in the CuS and control groups. Addition of Cu had no influence (P?>?0.05) on the serum triglyceride concentration, but lambs fed with CuP supplement had lower (P?<?0.05) serum cholesterol than the CuS and control animals. These results indicated that CuP supplemented at 10 mg/kg DM improved gain and enhanced the efficiency of nitrogen in male lambs.     

Combination of legume-based herbage and total mixed ration (TMR) maintains intake and nutrient utilization of TMR and improves nitrogen utilization of herbage in heifers

Diets combining herbage and total mixed rations (TMR) are increasingly used in temperate regions for feeding ruminants, but little information is available regarding the effects on nutrient intake and digestion of this feeding management in beef cattle. The aim of this study was to determine the effects of combining TMR (10% CP and 13% ADF), and legume-based herbage (14% CP and 27% ADF) on intake, nutrient digestion, ruminal fermentation, microbial N flow and glucose and nitrogen metabolism in heifers. The experiment was a 3×3 Latin square design replicated three times; each period lasted 18 days (10 adaptation days and 8 measurement days). Nine cross-bred (Aberdeen Angus×Hereford) heifers (214±18 kg) fitted with permanent rumen catheters and housed in individual metabolic cages were assigned to one of three treatments: 24 h access to TMR (T), 24 h access to herbage (H) or combined diets with 18 h access to TMR and 6 h access to herbage (T+H). Data were evaluated using a mixed model. Animals fed T+H (TMR 71% and herbage 29%) diets tended to have a higher dry matter intake as a proportion of their BW than animals fed T. The T+H diet did not change ruminal fermentation (pH, N–NH₃ and volatile fatty acids) or the N metabolism relative to the T diet, but increased the glucagon concentration and altered glucose metabolism. Conversely, animals fed T+H had increased purine derivatives excretion, increased N use efficiency for microbial protein synthesis and decreased plasma urea and urinary N excretion relative to animals fed H diet. The use of combined diets led to consumption of nutrients similar to a TMR diet, without reducing nutrient use and could improve N utilization compared with the herbage-only diet.     

Nutritional characterization of Mucuna pruriens: 4. Does replacing soybean meal with Mucuna pruriens in lamb diets affect ruminal,blood and tissue l-dopa concentrations?

The harmful effects of the 3,4-dihydroxy-l-phenylalanine (l-dopa) in Mucuna pruriens (Velvet bean) seeds have limited its use as a protein supplement for monogastrics and humans. Little is known about the extent of metabolism of Mucuna l-dopa in ruminants or its accumulation in ruminant tissues consumed as food by humans. This study aimed to determine if replacing soybean meal (SB) with Mucuna increases concentrations of l-dopa in rumen fluid, blood and muscle tissue of lambs. Twenty-seven RM lambs (RM; initial body weight, BW = 33.8 ± 5.44 kg) and 12 Florida Native (FN; initial BW = 24.9 ± 8.63 kg) lambs were assigned to four treatments and fed a basal diet of coastal bermudagrass hay, corn grain, and liquid molasses for 42 (FN) or 49 days (RM) and then slaughtered. Dietary supplements were formulated by substituting 0 (SB), 330 (Lo), 670 (Med) or at least 1000 (Hi) g/kg of SB with rolled Mucuna seeds (l-dopa, 24 g/kg dry matter, DM). Body weight was measured weekly and carcass characteristics and concentrations of l-dopa in rumen fluid, blood and the sterno-mandibularis muscle were measured at slaughter when concentrations of blood urea N, glucose, haptoglobin and cerruloplasmin were also measured. Lambs fed SB had higher (P<0.05) average daily gain than those fed Mucuna (0.20 versus 0.15 kg/day for RM; 0.21 versus 0.14 kg/day for FN). However, concentrate protein source did not affect dressing and concentrations of blood urea N, or blood glucose. Feeding the Hi diet versus the SB diet did not increase concentrations of blood cerruloplasmin, or l-dopa or concentrations of l-dopa metabolites in blood. No l-dopa was found in the ruminal fluid of the lambs and l-dopa concentrations in the sterno-mandibularis muscle were low (i.e., <5 ng l-dopa/g), and unaffected (P>0.05) by diet. Ingested Mucuna l-dopa was extensively metabolized in lambs, and did not accumulate to toxic levels in muscle tissues.     

Effects of Dietary Linseed Oil and Propionate Precursors on Ruminal Microbial Community,Composition, and Diversity in Yanbian Yellow Cattle

The rumen microbial ecosystem is a complex system where rumen fermentation processes involve interactions among microorganisms. There are important relationships between diet and the ruminal bacterial composition. Thus, we investigated the ruminal fermentation characteristics and compared ruminal bacterial communities using tag amplicon pyrosequencing analysis in Yanbian yellow steers, which were fed linseed oil (LO) and propionate precursors. We used eight ruminally cannulated Yanbian yellow steers (510 ± 5.8 kg) in a replicated 4 × 4 Latin square design with four dietary treatments. Steers were fed a basal diet that comprised 80% concentrate and 20% rice straw (DM basis, CON). The CON diet was supplemented with LO at 4%. The LO diet was also supplemented with 2% dl-malate or 2% fumarate as ruminal precursors of propionate. Dietary supplementation with LO and propionate precursors increased ruminal pH, total volatile fatty acid concentrations, and the molar proportion of propionate. The most abundant bacterial operational taxonomic units in the rumen were related to dietary treatments. Bacteroidetes dominated the ruminal bacterial community and the genus Prevotella was highly represented when steers were fed LO plus propionate precursors. However, with the CON and LO diet plus malate or fumarate, Firmicutes was the most abundant phylum and the genus Ruminococcus was predominant. In summary, supplementing the diets of ruminants with a moderate level of LO plus propionate precursors modified the ruminal fermentation pattern. The most positive responses to LO and propionate precursors supplementation were in the phyla Bacteriodetes and Firmicutes, and in the genus Ruminococcus and Prevotella. Thus, diets containing LO plus malate or fumarate have significant effects on the composition of the rumen microbial community.     

Growth performance,nutrient digestibility,blood parameters,and carcass characteristics by lambs fed an oregano and cobalt blend

Shifting ruminal fermentation via feeding a blend of oregano (Organum vulgare L.) essential oils and Co-lactate (EOC; Rum-A-Fresh, Ralco, Inc. Marshall, MN) could improve lamb growth and carcass performance. Eighteen Suffolk × Little Han Tail F1 male lambs (20.3 ± 0.23 kg BW and approximately 3 months old) were randomly assigned using a completely random design to one of three treatments. Treatments were (1) EOC0: basal ration without EOC, (2) EOC4: basal ration plus 4 g/d EOC, and (3) EOC7: basal ration plus 7 g/d EOC. Initial and 24 d BW was similar (P > 0.10), but at 48 and 72 d, lambs fed EOC7 demonstrated greater (P = 0.01) BW compared with EOC0 fed lambs, while lambs fed EOC4 were intermediate and similar (P > 0.05). Average daily gains (ADGs) for 0–24 and 0–72 d were greater (P < 0.05) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0, while DM intake was similar (P > 0.10). Feed conversions for 0–24 d were improved (P < 0.02) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. However, 0–72-d feed conversions were greater (P < 0.01) for lambs fed EOC7 compared to lambs fed EOC0, with lambs fed EOC4 being intermediate and similar (P > 0.05). DM, NDF, and ADF digestibilities were similar (P > 0.10) among treatments, while CP digestibility was greater (P < 0.01) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. Carcass weight and dressing percentages were improved (P < 0.01) for lambs fed EOC7 compared with lambs fed EOC0 and EOC4. Head width was greater (P > 0.01) for lambs fed EOC7 compared with lambs fed EOC0 and EOC4, while rump width was greater (P > 0.01) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. Plasma triglyceride and cholesterol concentrations were lower (P < 0.05) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0, while albumin, total serum protein, and glucose concentrations were greater (P < 0.05) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. Feeding an EOC blend as an alternative antibiotic growth promoter at 4 and 7 g/d linearly improved lamb growth performance, feed conversions, frame growth, carcass weights, dressing percentages, and immunity.     

Effects of feed withdrawal duration on animal behaviour,rumen microbiota and blood chemistry in feedlot cattle: implications for rumen acidosis

Feed withdrawal (FW) is a frequent issue in open outdoor feedlot systems, where unexpected circumstances can limit the animals’ access to food. The relationship among fasting period, animal behaviour during feed reintroduction (FR) and acidosis occurrence has not been completely elucidated. Twenty steers fitted with rumen catheters were fed a high-concentrate diet (concentrate : forage ratio 85 : 15) and were challenged by a protocol of FW followed by FR. The animals were randomly assigned to one of the four treatments: FW for 12 h (T12), 24 h (T24), 36 h (T36) or no FW (control group) followed by FR. The steers’ behaviour, ruminal chemistry, structure of the ruminal microbial community, blood enzymes and metabolites and ruminal acidosis status were assessed. Animal behaviour was affected by the FW–FR challenge ( P < 0.05). Steers from the T12, T24 and T36 treatments showed a higher ingestion rate and a lower frequency of rumination. Although all animals were suspected to have sub-acute ruminal acidosis (SARA) prior to treatment, a severe case of transient SARA arose after FR in the T12, T24 and T36 groups. The ruminal pH remained below the threshold adopted for SARA diagnosis ( pH value = 5.6) for more than three consecutive hours (24, 7 and 19 h in the T12, T24 and T36 treatments, respectively). The FW–FR challenge did not induce clinical acute ruminal acidosis even though steers from the T36 treatment presented ruminal pH values that were consistent with this metabolic disorder (pH threshold for acute acidosis = 5.2). Total mixed ration reintroduction after the withdrawal period reactivated ruminal fermentation as reflected by changes in the fermentation end-products. Ruminal lactic acid accumulation in steers from the T24 and T36 treatments probably led to the reduction of pH in these groups. Both the FW and the FR phases may have altered the structure of the ruminal microbiota community. Whereas fibrolytic bacterial groups decreased relative abundance in the restricted animals, both lactic acid producer and utiliser bacterial groups increased ( P < 0.05). The results demonstrated a synchronisation between Streptococcus (lactate producer) and Megasphaera (lactate utiliser), as the relative abundance of both groups increased, suggesting that bacterial resilience may be central for preventing the onset of metabolic disturbances such as ruminal acidosis. A long-FW period (36 h) produced rumen pH reductions well below and lactic acid concentration increased well above the accepted thresholds for acute acidosis without any perceptible clinical signs.     

Effects of slow-release urea fertilizers on urease activity,microbial biomass,and nematode communities in an aquic brown soil

A field experiment was carried out at the Shenyang Experimental Station of Ecology (CAS) in order to study the effects of slow-release urea fertilizers high polymer-coated urea (SRU1), SRU1 mixed with dicyandiamide DCD (SRU2), and SRU1 mixed with calcium carbide CaC₂ (SRU3) on urease activity, microbial biomass C and N, and nematode communities in an aquic brown soil during the maize growth period. The results demonstrated that the application of slow-release urea fertilizers inhibits soil urease activity and increases the soil NH₄ ⁺-N content. Soil available N increment could promote its immobilization by microorganisms. Determination of soil microbial biomass N indicated that a combined application of coated urea and nitrification inhibitors increased the soil active N pool. The population of predators/omnivores indicated that treatment with SRU2 could provide enough soil NH₄ ⁺-N to promote maize growth and increased the food resource for the soil fauna compared with the other treatments.     

Beet pulp substituted for corn silage and barley grain in diets fed to dairy cows in the summer months: feed intake,total-tract digestibility,and milk production

The responses of dairy cows to the substitution of beet pulp (BP) for grain or forage are not consistent, and heat stress may affect the response of dairy cows to this substitution. The effects of substituted BP for corn silage and barley grain on feed intake, performance, and ruminal parameters were evaluated using eight multiparous Holstein cows in a duplicated 4 × 4 Latin square design with 21-day periods. Cows were in mid-lactation (45.4 ± 3.6 kg/day milk production and 116 ± 10 days in milk) with an average BW of 664 ± 41.2 kg. Dietary treatments were as follows: 1) 0% BP (0BP, control, 38.5% barley grain, and 20.3% corn silage); 2) 12% BP (12BP, 32.5% barley grain, and 14.3% corn silage); 3) 18% BP (18BP, 29.5% barley grain, and 11.3% corn silage); and 4) 24% BP (24BP, 26.5% barley grain, and 8.3% corn silage). Cows were under mild heat stress and the average temperature–humidity index was 70.5; increasing BP caused a linear decrease in respiration rate (P < 0.01). Higher BP in the diet caused a linear increase in DM intake (P = 0.01) and NDF digestibility (P = 0.03). Dry and organic matter (OM) digestibilities tended to increase linearly with higher BP (P < 0.10). Milk yield, energy-corrected milk, protein, lactose, and fat production and content were not affected by the treatments. Increasing BP in the diet caused a linear decrease in feed efficiency and rumen ammonia (P < 0.05) and a tendency to a linear decrease in milk urea nitrogen (P < 0.10). Rumen pH and acetate to propionate ratio were not affected by the replacement. Total volatile fatty acid concentration in the rumen increased linearly with increasing the BP inclusion (P = 0.04). Acetate and butyrate (P = 0.07) proportion tended to increase, whereas propionate (P = 0.06) and isovalerate (P = 0.08) proportion tended to decrease linearly as BP was substituted for corn silage and barley grain. The results indicated that under mild heat stress condition, BP can be successfully substituted for barley grain and corn silage up to 24% of the diet without any negative effect on production and ruminal pH.     

Intake and digestion by lambs of dwarf elephant grass (Pennisetum purpureum Schum. cv. Mott) hay or hay supplemented with urea and different levels of cracked corn grain

This study was carried out to evaluate intake, digestibility, ruminal fermentation, nitrogen (N) retention and ruminal microbial protein synthesis in lambs fed dwarf elephant grass (Pennisetum purpureum Schum. cv. Mott) hay or hay supplemented with urea and 0, 5, 10 or 15 g/kg of live weight (LW) of cracked corn grain. Ten lambs (mean LW of 28 ± 0.9 kg), housed in metabolic cages, were used in a double 5 × 5 Latin Square experiment. Except fibre intake and digestibility, which was higher, the intake and digestibility of the others feed components, as well as ruminal microbial protein synthesis and N retention were lower in non-supplemented lambs. Corn supplementation increased total dry matter (DM) (P<0.05), organic matter (OM), non-structural carbohydrate (NSC) and energy intake (P<0.01) but decreased total neutral detergent fibre (aNDFom) (P<0.01) intake, as well as OM and aNDFom intake from the hay (P<0.01). Apparent DM, OM and energy digestibility, as well as OM true digestibility (OMTD) increased (P<0.01), and aNDFom digestibility decreased linearly (P<0.01) as corn supplementation increased. Total N intake was not influenced but, apparent and true N digestibility, as well as urinary N excretion decreased (P<0.01), and ruminal microbial N entering the small intestine increased linearly (P<0.01) as corn supplementation increased. However, the efficiency of ruminal microbial protein synthesis was similar for all treatments. Mean ruminal pH values and ammonia N concentrations decreased linearly (P<0.01) with level of corn supplementation. Ammonia N and amino acid, as well as peptide concentrations in ruminal fluid were quadratically related (P<0.01) with the time after feeding. Corn supplementation had a linear additive effect on total dry matter and digestible energy intake, as well as on N retention, but a linear negative effect on hay intake and on fibre digestibility. However, decreased forage digestibility by animals was probably neither related to lower ruminal pH, which values were always higher than 7.0, nor related to ruminal sugar concentrations, which were similar for all treatments.