Effect of glyphosate contaminated feed on rumen fermentation parameters and in sacco degradation of grass hay and corn grain

Four rumen fistulated wethers were used to investigate the effect of glyphosate contaminated feed on rumen fermentation. The rations were based on corn silage, urea and a vitamin-mineral premix, either in the absence or presence of 0.77?g glyphosate per kg DM. Furthermore, rations were fed either with or without aromatic amino acid supplementation. During four periods of 28 days, sheep received each of the four dietary treatments according to a Latin square. After 14 days of adaptation rumen fermentation parameters (pH, ammonia, volatile fatty acids) were measured on day 15 over a five-hour period after the morning feeding. The remaining 13 days served for in sacco degradation studies with grass hay and corn grain. Ammonia (NH₃) and pH of rumen fluid were within the normal range for all dietary treatments (NH₃: 9.1 – 32.3?mmol·l^???1, pH: 6.2 – 6.7). Neither rumen fermentation parameters nor in sacco DM and NDF degradation of incubated feedstuffs were significantly affected by glyphosate, with or without aromatic amino acid supplementation. Kinetic profiles of the in sacco dry matter and NDF degradation of grass hay were almost identical for the dietary treatments.     

Effect of by-product gypsum application rate to grass pasture,grass hay,and corn silage on fermentation by rumen microorganisms in continuous culture

A dual-flow continuous culture fermenter system was used to investigate ruminal fermentation in response to increased by-product gypsum application rate of three forages. The treatments included 0, 22, 45, and 90 tonnes/ha by-product gypsum applied to grass plots and 0, 22, and 45 tonnes/ha by-product gypsum applied to corn plots. Forage was harvested to represent grass pasture (GP), grass hay (GH), and corn silage (CS), dried, ground, and fed to fermenters at a rate of 60 g dry matter (DM)/day. Organic matter (OM) and neutral detergent fiber (aNDF) digestibilities, rumen pH, total volatile fatty acid (VFA) production, and N metabolism were not affected by gypsum application rate for all forage types. The GH had greater sulfur content than recommended as the maximum tolerable level by the National Research Council (NRC). The results of this study indicate that ruminal fermentation was not compromised when by-product gypsum was applied to GP, GH, or CS at rates up to 90 tonnes/ha. By-product gypsum application to pastures and crops shows promise as an economical soil amendment to reduce dissolved phosphorus loss in runoff, although potential animal health issues should be further evaluated.     

The effects of concentrate energy source on feed intake and rumen fermentation parameters of dairy cows offered a range of grass silages

The effects of concentrate energy source on feed intake and rumen fermentation parameters of lactating dairy cattle, offered one of three grass silages differing in fermentation and intake characteristics, were evaluated in a partially balanced changeover design experiment involving four rumen fistulated dairy cows. Three silages were harvested using different management practices prior to and at ensiling. Silages A and C and silage B were harvested from primary or secondary regrowths either untreated or treated with a bacterial inoculant. For silages A, B and C, dry matter (DM) concentrations were 334, 197 and 183 g/kg (S.E. 3.1), pH values 4.00, 4.79 and 4.80 (S.E. 0.042) and ammonia nitrogen (N) concentrations were 123, 319 and 295 g/kg total N (S.E. 20.0), respectively. Two concentrates were formulated to contain similar crude protein, effective rumen degradable protein, digestible undegradable protein and metabolisable energy concentrations but using different carbohydrate sources to achieve a wide range of starch concentrations. For the low and high starch concentrates starch concentrations were 17 and 304 g/kg DM and acid detergent fibre concentrations were 170 and 80 g/kg DM, respectively. The silages were offered ad libitum, supplemented with 10 kg fresh concentrate daily. For silages A, B and C, DM intakes were 10.9, 7.2 and 8.6 kg/day and concentrate energy sources did not alter (P>0.05) intake. Increasing the level of starch in the concentrate decreased the molar concentration of acetate (P<0.05) and tended to increase the molar concentration of propionate (P<0.1). Silage type altered the molar concentration of acetate (P<0.01) and the acetate:propionate ratio (P<0.05). There were no silagetype×concentrate interactions (P>0.05) on silage intake or rumen fermentation parameters. It is concluded that when concentrate and silage form equal proportions of the diet, the composition of the silage has an over-riding influence on rumen fermentation parameters. Furthermore, the changes in milk fat concentration, observed in a concurrent production study, due to changes in silage and concentrate types can be accounted for by changes in the ratio of lipogenic to glucogenic precursors in the rumen fluid.     

Feeding corn grain steeped in citric acid modulates rumen fermentation and inflammatory responses in dairy goats

Cereal grains treated with organic acids were proved to increase ruminal resistant starch and can relieve the risk of ruminal acidosis. However, previous study mainly focussed on acid-treated barley, the effects of organic acid-treated corn is still unknown. The objectives of this study were to evaluate whether feeding ground corn steeped in citric acid (CA) would affect ruminal pH and fermentation patterns, milk production and innate immunity responses in dairy goats. Eight ruminally cannulated Saanen dairy goats were used in a crossover designed experiment. Each experimental period was 21 day long including 14 days for adaption to new diet and 7 days for sampling and data collection. The goats were fed high-grain diet contained 30% hay and 70% corn-based concentrate. The corn was steeped either in water (control) or in 0.5% (wt/vol) CA solution for 48 h. Goats fed CA diet showed improved ruminal pH status with greater mean and minimum ruminal pH, and shorter (P<0.05) duration of ruminal pH<5.6 and less area of ruminal pH<5.6, 5.8 and 6.0. Concentration of total volatile fatty acid and molar proportion of propionate were less but the molar proportion of acetate was greater (P<0.05) in goats fed the CA diet than the control diet. Concentration of ruminal lipopolysaccharide (LPS) was lower (P<0.05) and that of lactic acid also tended (P<0.10) to be lower in goats fed CA than the control. Although dry matter intake, actual milk yield, yield and content of milk protein and lactose were not affected, the milk fat content and 4% fat-corrected milk tended (P<0.10) to be greater in goats fed CA diet. For the inflammatory responses, peripheral LPS did not differ, whereas the concentration of LPS binding protein and serum amyloid A tended (P<0.10) to be less in goats fed CA diet. Similarly, goats fed CA diet had less (P<0.05) concentration of haptoglobin and tumour necrosis factor. These results indicated that feeding ground corn treated with CA effectively improved ruminal pH status, thus alleviated the risk of ruminal acidosis, reduced inflammatory response, and tend to improve milk yield and milk fat test.     

Effect of rare earth elements on in vitro rumen microbial fermentation and feed digestion

The objectives of this study were to investigate the effects of rare earth elements (REEs) on in vitro rumen fermentation, gas production, microbial protein synthesis and nutrient digestion using in vitro batch culture and continuous culture technique. A mixture of REE containing (g/kg) 380 g of LaCI₃·6H₂O, 521 g of CeCI₃·6H₂O, 30 g of PrCI₃·6H₂O and 69 g chlorides of other light REEs. The experimental diet consisted of 885 g/kg barley grain, 84 g/kg barley silage and 31 g/kg supplement (dry matter (DM) basis). Diet supplemented with different dosages of REE (control, no additional REE; low, 400 mg/kg REE; and high, 800 mg/kg REE, DM basis) were incubated for 4, 8, 14 and 24 h in diluted rumen fluid. At the end of 24 h of incubation, gas production and concentration of volatile fatty acid (VFA) linearly increased with increasing REE supplementation; whereas, influence of REE supplementation on VFA profile was marginal. Dry matter disappearance was not affected (P>0.10). Six dual-flow continuous culture fermenters were used in a replicated 3 × 3 Latin square with same treatments and same diet used in the batch culture. Mean ruminal pH (5.71) and total VFA (93.6 mM) concentration were not affected by supplementation of REE. The molar proportion (mol/100 mol) of acetate (39.1) and propionate (50.5) was similar among the treatments. However, the proportion (mol/100 mol) of butyrate was higher with the high REE (6.6) than with low REE (5.3) or the control (5.8). Ruminal true digestibilities of organic matter (OM) (0.785, 0.811 and 0.828), acid detergent fibre (0.360, 0.431 and 0.432) and crude protein (0.496, 0.590 and 0.589) for control, low and high REE, respectively, linearly increased with increasing REE supplementation, whereas, the increase in ruminal digestibility from low to high dosage of REE was minimal. Microbial nitrogen (N) production (g/day) and microbial efficiency (g N/kg of truly fermented OM) were not affected by treatments. Improvement of ruminal digestibility of OM due to REE supplementation was attributed to the increase in digestibility of fibre and degradability of protein. The results suggest that REE supplementation improved ruminal fibrolytic and proteolytic activities.     

Effect of inclusion of tree leaves in feed on nutrient utilization and rumen fermentation in sheep

The effect of inclusion of tree leaves in mustard (Brassica campestris) straw (MS) based complete feed blocks (CFB) on nutrient utilization and rumen fermentation was studied in adult male sheep. Four types of CFB diets (Roughage:Concentrate:Molasses, 70:25:5) were prepared. The compaction process increased bulk density (g/cm(3)) of MSB, MSNL, MSSL and MSAL by 2.9, 1.79, 2.40 and 2.26 times, respectively. The dry matter intake (g/day) was higher (P<0.05) in MSSL and MSAL than in MSB. Digestibility coefficients of crude protein and hemicellulose increased (P<0.05) due to inclusion of tree leaves, while digestibility of dry matter and organic matter showed small improvement. However, inclusion of tree leaves did not affect digestibility of neutral detergent fibre, cellulose and energy. The concentration of total volatile fatty acids in rumen was significantly higher in MSAL than in MSB or MSSL. Blood bio-chemical parameters were within the normal physiological range in all the groups.     

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

It was hypothesized that differences in starch degradability account for observed differences in rumen vaccenic acid (t11-18:1) and milk rumenic acid (RA) concentrations. To test this hypothesis, starch degradability was varied through grain source and by processing. Eight Holstein cows in mid-lactation were assigned to two 4 × 4 Latin squares with four 21-day periods and four diets: dry rolled barley, ground barley, dry rolled corn and ground corn. Diets contained similar starch content and were supplemented with whole sunflower seed to provide similar total polyunsaturated fatty acid (PUFA) (18:2n-6 + 18:3n-3) contents. Forage/concentrate ratios of all diets were 42 : 58. Rumen, plasma and milk samples were collected in the third week of each period. In situ degradation rates (%/h) for rolled corn, ground corn, rolled barley and ground barley were 5.4, 8.9, 17.0 and 19.4, respectively, for dry matter (DM) and 6.3, 10.8, 25.3 and 43.8, respectively, for starch. DM intakes were greater for corn-based diets (CBD) than for barley-based diets (BBD) with no difference between rolled and ground diets. Daily minimum rumen pH was less (5.2 v. 5.5) and pH duration <5.8 (h/d) was greater (7.4 v. 4.3) for BBD than for CBD. Milk fat content and yield were less for BBD than for CBD with greater values observed for rolling compared with grinding. Variability in milk fat yield was strongly related (R2 = 0.55; P < 0.01) to total starch intake (45%) and milk c9t11-CLA (10%) and none of the t-18:1 isomers or CLA isomers that are typically associated with milk fat depression entered the model. The concentrations (%) of t10-18:1 and t11-18:1 were greater for BBD than for CBD in rumen contents (t10-18:1, 3.5 v. 1.3; t11-18:1, 3.2 v. 1.9), plasma (t10-18:1, 1.2 v. 0.2; t11-18:1, 0.97 v. 0.58) and milk (t10-18:1, 3.8 v. 1.0; t11-18:1, 2.6 v. 1.7) despite greater total PUFA intakes for CBD. Milk RA concentration was greater for BBD than for CBD (1.46 v. 0.89) but was not influenced by the method of grain processing. This study clearly demonstrated that the milk content and profile of t-18:1 and CLA isomers were more strongly influenced by the source of grain starch (barley > corn) than by the method of grain processing indicating that factors inherent in the source of starch were responsible for the observed differences and these factors could not be modified by the processing methods used in this study.     

Effect of elemental nano-selenium on feed digestibility,rumen fermentation,and purine derivatives in sheep

The objective of this experiment was to study the effect of elemental nano-selenium (NS) on feed digestibility, rumen fermentation, and urinary purine derivatives in sheep. Eight male ruminally cannulated sheep (42.5 ± 3.2 kg of body weight, BW) were used in a replicated 4×4 Latin square experiment in four 20 day periods. Depending on treatment designation, sheep were fed the basal diet supplemented with 0 (control), 0.3, 3 and 6 g of nano-Se/kg dry matter (DM). Ruminal pH (range of 6.68–6.80) and ammonia N concentration (range of 9.95–12.49 mg/100 mL) was decreased (P<0.01), and total VFA concentration (range of 73.63–77.72 mM) was increased linearly (P<0.01) and quadratically (P<0.01) with increasing nano-Se supplementation. The ratio of acetate to propionate was linearly (P<0.01) and quadratically (P<0.01) decreased due to the increasing of propionate concentration. In situ ruminal neutral detergent fiber (aNDF) degradation of Leymus chinensis and crude protein (CP) of soybean meal were linearly (P<0.01) and quadratically (P<0.01) improved by feeding nano-Se. Similarly, nutrients digestibility in the total tract and urinary excretion of purine derivatives were also quadratically (P<0.01) changed by increasing nano-Se supplementation. The present results indicated that nano-Se supplementation in basal diet improved rumen fermentation and feed utilization. Nano-Se could also stimulate rumen microbial activity, digestive microorganisms or enzyme activity. The optimum dose of nano-Se was about 3.0 g/kg dietary DM in sheep.     

Effect of combined herbal feed additives on methane,total gas production and rumen fermentation

The present study was to evaluate effect of herbal feed additives on methane and total gas production during the rumen fermentation for environment and animal health concern. Different parts of the five medicinal plants were selected such as leaf and small stems of Ocimum sanctum (Tulsi), roots of Curcuma longa (Haldi), fruits of Emblica officinalis (Amla), leaves of Azadirachta indica (Neem) and leaves and small stem of Clerodendrum phlomidis (Arni) for our study. Addition of different herbal additive combinations did not influence IVDMD and total gas production however methane production (mg/g of substrate DM) was significantly (P<0.05) reduced in Amla: Neem and Neem: Arni combinations. Total nitrogen significantly (P<0.01) increased in the combinations of Tulsi: Haldi and Amla: Neem. TCA–ppt-N is significantly (P<0.01) increased in Tulsi: Haldi, Haldi: Amla, Amla: Neem and Neem: Arni however NH₃-N (mg/dl) significantly decreased in all treatments. We conclude that the screening of plant combinations, Amla: Neem and Neem: Arni have potential to decrease methane production and our herbal feed supplements have no side-effects on the ruminant in small amount.     

Effect of whole-plant corn silage treated with lignocellulose-degrading bacteria on growth performance,rumen fermentation,and rumen microflora in sheep

Lignification of cellulose limits the effective utilisation of fibre in plant cell wall. Lignocellulose-degrading bacteria secrete enzymes that decompose lignin and have the potential to improve fibre digestibility. Therefore, this study aimed to investigate the effect of whole-plant corn silage inoculated with lignocellulose-degrading bacteria on the growth performance, rumen fermentation, and rumen microbiome in sheep. Twelve 2-month-old male hybrid sheep (Dorper ♂ × small-tailed Han ♀) were randomly assigned into two dietary groups (n = 6): (1) untreated whole-plant corn silage (WPCS) and (2) WPCS inoculated with bacterial inoculant (WPCSB). Whole-plant corn silage inoculated with bacterial inoculant had higher in situ NDF digestibility than WPCS. Sheep in the WPCSB group had significantly higher average daily gain, DM intake, and feed conversion rate than those in the WPCS group (P < 0.05). Furthermore, higher volatile fatty acid concentrations were detected in WPCSB rumen samples, leading to lower ruminal pH (P < 0.05). The WPCSB group showed higher abundance of Bacteroidetes and lower abundance of Firmicutes in the rumen microbiome than the WPCS group (P < 0.05). Multiple differential genera were identified, with Prevotella being the most dominant genus and more abundant in WPCSB samples. Moreover, the enriched functional attributes, including those associated with glycolysis/gluconeogenesis and citrate cycle, were more actively expressed in the WPCSB samples than in the WPCS samples. Additionally, certain glucoside hydrolases that hydrolyse the side chains of hemicelluloses and pectins were also actively expressed in the WPCSB microbiome. These findings suggested that WPCSB increased NDF digestibility in three ways: (1) by increasing the relative abundance of the most abundant genera, (2) by recruiting more functional features involved in glycolysis/gluconeogenesis and citrate cycle pathways, and (3) by increasing the relative abundance and/or expression activity of the glucoside hydrolases involved in hemicellulose and pectin metabolism. Our findings provide novel insights into the microbial mechanisms underlying improvement in the growth performance of sheep/ruminants. However, the biological mechanisms cannot be fully elucidated using only metagenomics tools; therefore, a combined multi-omics approach will be used in subsequent studies.     

Effects of the level of feed intake and ergot contaminated concentrate on ruminal fermentation and on physiological parameters in cows

The aim of the present study was to examine the effects of ergot contaminated feed concentrate at differing levels of feed intake on ruminal fermentation, and on various physiological parameters of dairy cows. Twelve double fistulated (in the rumen and the proximal duodenum) Holstein Friesian cows were fed either a control diet (on a dry matter (DM) base: 60% maize silage, 40% concentrate) or a diet containing ergot alkaloids (concentrate contained 2.25% ergot resulting in an ergot alkaloid concentration of the daily ration between 505 and 620 (μg/kg DM) over a period of four weeks. Daily feed amounts were adjusted to the current performance which resulted in a dry matter intake (DMI) variation between 6.0 and 18.5 kg/day. The resulting ergot alkaloid intake varied between 4.1 and 16.3 (μg/kg body weight when the ergot contaminated concentrate was fed. Concentrations of isovalerate, propionate and ammonia nitrogen in the rumen fluid were significantly influenced by ergot feeding, and the amount of ruminally undegraded protein, as well as the fermentation of neutral detergent fibre, tended to increase with the ergot supplementation at higher levels of feed intake, which might indicate a shift in the microbial population. Other parameters of ruminal fermentation such as ruminai pH, fermented organic matter as a percentage of intake, or the amount of non-ammonia nitrogen measured at the duodenum were not significantly influenced by ergot feeding. The activities of liver enzymes (aspartate aminotransferase, γ-glutamyltransferase, glutamate dehydrogenase, creatine kinase) in the serum were not affected by ergot feeding. The rectal measured body temperature of the cows significantly increased after ergot administration (p=0.019). Thus, body temperature can be regarded as a sensitive parameter to indicate ergot exposure of dairy cows.     

Effect of substituting wet corn gluten feed and corn stover for alfalfa hay in total mixed ration silage on lactation performance in dairy cows

Wet corn gluten feed (WCGF) is a high moisture feed containing rapidly digestible, non-forage fiber and protein. The objective of this study was to investigate the effect of substituting WCGF and corn stover for alfalfa hay in total mixed ration (TMR) silage on lactation performance and nitrogen balance in dairy cows. Nine multiparous Holstein dairy cows (BW = 532 ± 28.9 kg and day in milk = 136 ± 5.6 d; mean ± SD) were used in a replicated 3 × 3 Latin square design with 21-d periods (14 d of diet adaption and 7 d of sample collection). Groups were balanced for parity, day in milk, and milk production and consumed one of three treatment diets during each period. The treatment diets were fed as TMR and contained similar concentrate mixtures and corn silage but different proportions of roughage and WCGF. The three treatments were: (1) 0% WCGF, 0% corn stover, and 22.1% alfalfa hay (0% WCGF); (2) 6.9% WCGF, 3.4% corn stover, and 11.8% alfalfa hay (7% WCGF); and (3) 13.3% WCGF, 4.9% corn stover, and 3.9% alfalfa hay (13.3% WCGF). Compared to the 0% WCGF diet, the cows fed the 7% and 13.3% WCGF diets had a higher milk yield and concentration of milk fat, protein, lactose, and total solids. Effective degradability of DM was higher in the cows fed the 7% and 13.3% WCGF diets than it was with the 0% WCGF diet. Cows fed the 13.3% WCGF had a higher CP effective degradability and a lower rumen undegraded protein than cows fed the 0% WCGF diet. The concentration of ruminal volatile fatty acids and ammonia-N was higher in cows fed the 7% and 13.3% WCGF diets than cows fed the 0% WCGF diet. The fecal N was lower in cows fed the 7% and 13.3% WCGF diets than it was in cows fed the 0% WCGF diet. Milk N secretion and milk N as a percent of N intake were higher in cows fed the 13.3% WCGF diet than cows fed the 0% and 7% WCGF diets. In conclusion, it appears that feeding a TMR silage containing WCGF and corn stover in combination, replacing a portion of alfalfa hay, may improve lactation performance and nitrogen utilization for lactating dairy cows.     

Effect of glyphosate on auxin transport in corn and cotton tissues

Basipetal auxin transport in 6-day-old dark-grown corn coleoptiles was severely inhibited by increasing levels of glyphosate applied during the transport period.     

Effect of maize silage to grass silage ratio and feed particle size on ruminal fermentation in vitro

The effect of the forage source on ruminal fermentation in vitro was investigated for fine (F) and coarse (C) milled diets, using a modified Hohenheim gas production test and a semi-continuous rumen simulation technique (Rusitec). It was hypothesised that the replacement of maize silage by grass silage might lead to associative effects and that interactions related to particle size variation could occur. Five diets with a maize silage to grass silage ratio of 100 : 0, 79 : 21, 52 : 48, 24 : 76 and 0 : 100 differed in their content of CP and carbohydrate fractions, as well as digestible crude nutrients, derived from a digestibility trial with wether sheep. For in vitro investigations, the diets were ground to pass a sieve of either 1 mm (F) or 4 mm (C) perforation. Cumulative gas production was recorded during 93 h of incubation and its capacity decreased with increasing proportion of grass silage in the diet. Across all diets, gas production was delayed in C treatments compared with F treatments. Degradation of crude nutrients and detergent fibre fractions was determined in a Rusitec system. Daily amounts of NH3-N and short-chain fatty acids (SCFA) were measured in the effluent. Degradation of organic matter (OM) and fibre fractions, as well as amounts of NH3-N, increased with stepwise replacement of maize silage by grass silage. Degradability of CP was unaffected by diet composition, as well as total SCFA production. In contrast to the results of the gas production test, degradation of OM and CP was higher in C than in F treatments, accompanied by higher amounts of NH3-N and SCFA. Interactions of silage ratio and particle size were rare. It was concluded that the stepwise replacement of maize silage by grass silage might lead to a linear response of most fermentation characteristics in vitro. This linear effect was also supported by total tract digestibility data. However, further investigations with silages of variable quality seem to be necessary.     

Effect of roughage level in a total mixed ration on feed intake, ruminal fermentation patterns and chewing activity of early-weaned calves with ad libitum access to grass hay

In this study, two total mixed rations (TMR, based on dry ingredients) consisting (per kg dry matter (DM)) of 300 or 400 g finely chopped hay mixture of grass and alfalfa (H30 versus H40) were compared concerning their effects on dry matter intake (DMI), ruminal fermentation patterns and chewing activity of early-weaned (8 weeks milk-fed) calves. Ten ruminally cannulated male German Holstein calves were randomly assigned to two dietary treatments (n = 5) and observed from an age of 8–15 weeks. One group received the H30 (11.3 MJ metabolizable energy (ME)/kg DM) and the other the H40 (10.7 MJ ME/kg DM) TMR. All calves received grass hay (9.0 MJ ME/kg DM) separately. Water, TMR and hay were offered ad libitum twice daily (08:00 and 16:00 h). Rumen fluid was collected via cannula at an age of 9, 11, 13 and 15 weeks, twice weekly just prior to as well as 1, 3, 5 and 7 h after morning feeding. Chewing activity was recorded by a special head collar. As the calves aged DMI increased rapidly congruent with the recommended range for weaned calves. Because of the differing energy supply, calves receiving the H30 TMR were heavier than calves receiving the H40 TMR (139 kg versus 123 kg, P=0.007). During the trial ruminal pH of all calves were within the target range (6.2 ± 0.5), indicating physiological ruminal fermentation patterns. Daily mean ruminal pH was uninfluenced by treatment, however at an age of 13 and 15 weeks H30 showed a higher short chain fatty acid (SCFA) level than H40 (P=0.098; P=0.036). At an age of 15 weeks H30 showed a critical decrease in ruminal pH (3 h after feeding: 5.7) corresponding to a higher ruminal SCFA concentration (148.2 mmol/L, P=0.007). Chewing activity was well developed at an early age due to an increasing DMI after weaning. At an age of 15 weeks chewing activity (per day: 613–743 min total chewing; 358–418 min rumination) was similar to that of adult cows. In summary, feeding a dry TMR consisting per kg DM of 300–400 g hay to early-weaned calves can be recommended for a successful calf rearing up to an age of 15 weeks.     

Effect of complete feed blocks or grazing and supplementation of lambs on performance, nutrient utilisation, rumen fermentation and rumen microbial enzymes

A study to compare two feeding systems, stall feeding (SF) and grazing plus supplementation (GR) was carried out, based on intake, performance and rumen fermentation characteristics of lambs. While SF animals received ad libitum complete feed blocks (CFB), GR animals were allowed grazing for 8 h on a pasture and supplemented with concentrate mixture at 250 g per head per day. Intake in grazing animals was determined using chromium III oxide as internal marker. Intake of dry matter (DM), crude protein (CP) and organic matter (OM) were higher ( P < 0.01) in SF than in GR animals. Similarly, digestibility of OM, CP and energy were higher ( P < 0.01) in SF animals. Average daily gain in SF animals (101 g) was significantly ( P < 0.01) higher than in GR animals (78 g) but total wool yield was similar for the two groups (856 g, SF; 782 g, GR). The pH of the rumen content, concentration of total volatile fatty acids and total activities of carboxymethyl cellulase, xylanase and esterase in the rumen liquor were similar. The concentrations (mg/dl) of total nitrogen (125, SF; 63, GR) and NH₃-nitrogen (42, SF; 31, GR) were higher in SF animals than that of GR animals. A significantly higher activity ( P < 0.05) of microcrystalline cellulase (24.5 v. 7.7 units) and lower activity ( P < 0.05) of protease (309 v. 525 units), was observed in the rumen of SF animals than in GR animals. SF animals could therefore harness more energy through degradation of plant cell walls thus reducing breakdown of plant proteins as gluconeogenic source. The SF system of feeding where CFB was offered to sheep appeared superior to GR in terms of intake, nutrient utilisation and animal performance. Therefore the SF feeding system where CFB are offered to animals can be advocated as an alternative to grazing and supplementation feeding strategy for sheep production, especially where the pastures are highly eroded and need resting for regeneration or curing. The CFB feeding can also be adopted under adverse conditions like drought and famine, a common phenomenon in arid and semiarid conditions.     

Effects of pH on distribution of Listeria ribotypes in corn, hay, and grass silage.

Listeria app, isolated from 13 of 129 (10%) corn silage samples, 21 of 76 (28%) hay silage samples, and 3 of 5 (60%) grass silage samples during a previous Vermont survey were subjected to automated ribotype (RT) analysis. The 13 positive corn silage samples contained 3 Listeria monocytogenes isolated (three RTs, including one known clinical RT) and 10 L. innocua isolates (four RTs). Similarly, 2 L. monocytogenes isolates (two RTs) and 19 L. innocua isolates (three RTs) were identified in the 21 positive hay silage samples. The three positive grass silage samples contained two L. innocua isolates (two RTs) and one isolate of L. welshimeri. One hundred seven of 129 (83%) high-quality (pH < 4.0) corn silage samples accounted for 8 of 13 Listeria isolates from corn silage, including isolates belonging to one L. monocytogenes clinical RT. In contrast, low-quality hay silage (70 of 76 [92%] samples having a pH of > or = 4.0) harbored 20 of 21 isolates, including isolates belonging to two nonclinical L. monocytogenes RTs. Poor-quality silage is readily discernible by appearance; however, these findings raise new concerns regarding the safety of high-quality (pH < 4.0) corn silage, which can contain Listeria spp., including L. monocytogenes strains belonging to RTs of clinical importance in cases of food-borne listeriosis.