Effects of quebracho tannin extract (Schinopsis balansae Engl.) and activated charcoal on nitrogen balance,rumen microbial protein synthesis and faecal composition of growing Boer goats

Under irrigated arid conditions, organic fertiliser rich in slowly decomposable nitrogen (N) and carbon (C) is needed for soil fertility maintenance. Feeding ruminants with condensed tannins will lower ruminal protein degradation, reduce urinary N excretion and might increase the faecal fraction of slowly decomposable N. Supplementation with activated charcoal (AC) might enrich manure with slowly degrading C. Therefore, we investigated the effects of feeding quebracho tannin extract (QTE) and AC on the N balance of goats, the efficiency of microbial protein synthesis in the rumen (EMPS) and the composition of faeces. The feeding trial comprised three periods; in each period, 12 male Boer goats (28 ± 3.9 kg live weight) were assigned to six treatments: a Control diet (per kg diet 500 g grass hay and 500 g concentrate) and to further five treatments the Control diet was supplemented with QTE (20 g and 40 g/kg; diets QTE2 and QTE4, respectively), with AC (15 g and 30 g/kg, diets AC1.5 and AC3.0, respectively) and a mixture of QTE (20 g/kg) plus AC (15 g/kg) (diet QTEAC). In addition to the N balance, EMPS was calculated from daily excretions of purine derivatives, and the composition of faecal N was determined. There was no effect of QTE and AC supplementation on the intake of organic matter (OM), N and fibre, but apparent total tract digestibility of OM was reduced (p = 0.035). Feeding QTE induced a shift in N excretion from urine to faeces (p ≤ 0.001) without altering N retention. Total N excretion tended to decrease with QTE treatments (p = 0.053), but EMPS was not different between treatments. Faecal C excretion was higher in QTE and AC treatments (p = 0.001) compared with the Control, while the composition of faecal N differed only in concentration of undigested dietary N (p = 0.001). The results demonstrate that QTE can be included into diets of goats up to 40 g/kg, without affecting N utilisation, but simultaneously increasing the excretion of slowly decomposable N and C fractions. Feeding AC up to 30 g/kg of the diet increases slowly degradable faecal C concentration, without negative effects on N metabolism of goats.     

Effect of different levels of concentrate on ruminal microorganisms and rumen fermentation in Nellore steers

The aim of this study was to investigate the effect of different dietary levels of concentrate on feed intake, digestibility, ruminal fermentation and microbial population in steers. Eight Nellore steers fitted with ruminal cannulas were used in a double 4 × 4 Latin square design experiment. The dietary treatments consist of four different proportions of concentrate to roughage: 30:70, 40:60, 60:40 and 80:20% in the dry matter, resulting in Diets 30, 40, 60 and 80, respectively. The roughage was corn silage, and the concentrate was composed of corn, soybean meal and urea. Apparent digestibility of organic matter and crude protein showed a linear association with concentrate proportion (p = 0.01), but the increased concentrate levels did not affect the digestibility of fibre. The lowest ruminal pH-values were observed in animals fed with Diet 80, remaining below pH 6.0 from 6 h after feeding, while in the other diets, the ruminal pH was below 6.0 not before 12 h after feeding. After feeding Diet 80, the ammonia concentration in the rumen was significantly the highest. Higher dietary concentrate levels resulted in a linear increase of propionic acid concentrations, a linear reduction of the ratio acetic acid to propionic acid (p < 0.01) and a linear increased synthesis of microbial nitrogen (p < 0.001). The predicted production of methane was lower in diets with greater amounts of concentrate (p = 0.032). The population of methanogens, R. flavefaciens and R. albus decreased with higher concentrate levels, while the population of S. ruminantium increased (p < 0.05). The results indicate that greater amounts of concentrate do not decrease ruminal pH-values as much as expected and inhibit some cellulolytic bacteria without impairing the dry matter intake and fibre digestibility in Nellore steers.     

Parameters of fermentation and rumen microbiota of Nellore steers fed with different proportions of concentrate in fresh sugarcane containing diets

The objective of this study was to evaluate the effect of a fresh sugarcane-based diet and different roughage-to-concentrate ratios (70:30, 60:40, 40:60 and 20:80) on the rumen microbiota associated with rumen fermentation parameters and the intake and apparent digestibility of nutrients in Nellore steers. Eight rumen-cannulated Nellore steers (331 ± 8 kg BW) were distributed in a double 4 × 4 Latin square design balanced for the control of the residual effect. The ruminal pH decreased (p < 0.01) and the concentrations of N–NH₃, isovaleric and valeric acids increased linearly (p < 0.05) with an increase dietary concentrate level. Furthermore, an increased concentrate proportion reduced the population of Fibrobacter succinogenes and Ruminococus flavefaciens (p < 0.01) and increased the population of Selenomonas ruminantium and Megasphaera elsdenii (p < 0.01). The protozoa count revealed a predominance of the genus Entodinium. The synthesis of microbial N [g/d] and the efficiency of microbial synthesis [g of microbial N/kg of organic matter apparently digested in the rumen] increased as the proportion of concentrate was increased (p < 0.05). Therefore, it can be concluded that an increasing proportion of concentrate in sugarcane-containing diets enhances the synthesis of microbial protein and does not alter the fibre digestibility, although the population of fibre fermenting bacteria was reduced.     

Effects of feeding high-quality hay with graded amounts of concentrate on feed intake,performance and blood metabolites of cows in early lactation

Dairy cows are commonly fed energy-dense diets with high proportions of concentrate feedstuffs to meet the increased energy needs of early lactation. However, feeding large amounts of concentrates may cause rumen acidosis and impact cow health. The hypothesis tested was that the energy supply and metabolic health of early-lactation Simmental cows can be maintained when high-quality hay rich in water-soluble carbohydrates (WSC) and crude protein (CP) is fed, despite the proportion of concentrates in the diet being reduced or even excluded. Twenty-four Simmental cows were allocated to one of four feeding groups beginning 10 d before the expected calving date, until 28 d thereafter. The feeding groups were 60CH (60% conventional fibre-rich hay plus 40% concentrate feed), 60HQH (60% high-quality hay plus 40% concentrate feed), 75HQH (75% high-quality hay plus 25% concentrate feed) and 100HQH (100% high-quality hay). The fibre-rich hay and high-quality hay differed in WSC content (110 g vs. 198 g of dry matter (DM)), neutral detergent fibre (646 g vs. 423 g of DM) and CP (65 g vs. 223 g of DM). Individual feed intake and milk production were monitored daily, and blood samples were collected weekly. Dry matter intake (DMI) and milk yield increased post partum, but 4 weeks post partum, the DMI of cows fed 100HQH only reached a daily mean DMI of 18.6 kg, whereas the DMI of the other groups averaged 21.9 kg (p < 0.046). The negative energy balance was less pronounced in cows fed 75HQH since they showed similar milk yields to the cows fed 60CH and 100HQH, but their energy intake was higher. Concentrations of milk components were similar across rations 60CH, 60HQH and 75HQH, as were most of blood parameters. Cows fed 100HQH responded to the energy deficit post partum with a higher ratio of non-esterified fatty acids to cholesterol and a higher concentration of ß-hydroxybutyrate (significant in comparison to cows fed 75HQH, p < 0.05). In conclusion, feeding high-quality hay with a WSC content of 20% in DM has the potential to decrease the proportion of concentrates in dairy cow feeding in early lactation, but cannot fully replace their supplementation due to a limited rumen capacity for forage intake.     

Effect of daily concentrate intake at weaning on performance of belgian blue double-muscled rearing calves

Abstract

Weaning at a different daily concentrate intake was investigated during a 140-d experimental period, using 54 male and 68 female newborn Belgian Blue double-muscled animals. They were divided into three comparable groups and received milk at 10% of their birth weight up to weaning. Concentrate was levelled off at a maximum daily intake of 3 kg, while grass hay was freely available. Weaning occurred at a daily concentrate intake level (CL) of 0.5, 0.75 and 1.0 kg, respectively. Weaning at an increased CL prolonged the milk-feeding period by 13.1 and 14.6 days, and resulted in a higher pre- and post-weaning growth rate (p < 0.05). Daily gain during the entire experimental period averaged 0.84, 0.85 and 0.88 kg for the respective groups (p = 0.065). Daily concentrate intake was not different among groups, with only a small effect of CL on intake around weaning. Early weaning resulted in a significant reduction of hay intake (p = 0.032). Total daily net energy intake increased slightly with a higher CL at weaning, so that energy conversion was slightly improved, amounting to 17.7, 17.6 and 17.4 MJ/kg gain, respectively. Energy balance during the first week after weaning was negative for CL 0.5 kg (?22%), while it was close to 0 for CL 0.75 kg (?2%) or positive for CL 1.0 kg. Most effects of CL at weaning were similar for males and females, but male calves tended to have a higher intake and a faster growth rate than females. It can be concluded that weaning should be delayed until Belgian Blue double-muscled calves consume at least 0.75 kg per day or more for reasons of welfare, although performance was hardly improved by weaning at a daily concentrate intake of more than 0.5 kg per day.     

Characterisation of particle dynamics and turnover in the gastrointestinal tract of Holstein cows fed forage diets differing in fibre and protein contents

An improved understanding of the role of forage quality on the processes of particle dynamics and turnover is important for the development of healthier and cost-effective feeding strategies that aim at lowering the proportions of concentrates in the diets of cattle. The aim of this study was to evaluate the effects of feeding hays of different qualities on particle dynamics, digestion kinetics and turnover in the gastrointestinal tract (GIT). Three non-lactating, rumen fistulated Holstein cows were fed diets consisting exclusively of hay with either low quality [Group LH; 605 ± 12.4 g/kg neutral detergent fibre (NDF) and 63 ± 4.7 g/kg crude protein (CP)] or good quality (Group GH; 551 ± 20.1 g/kg NDF and 116 ± 3.6 g/kg CP). Data showed that in situ dry matter (DM) disappearance of the soluble fraction was greater for Group GH (p < 0.05). Feeding good quality hay also lowered the proportion of particles >1.18 mm particularly during the eating process (p < 0.05). Changes in the particle size occurring afterwards were greater for Group GH as well (p < 0.05); approximately 30% in the comminution in the particle size occurred postruminally. Feeding hay of good quality lowered DM content of solid rumen digesta (p < 0.05), accelerated (p < 0.05) the turnover rate of DM and NDF in the GIT and increased DM intake (p < 0.05). In conclusion, feeding forages of better quality significantly promoted degradation processes and kinetics in the GIT with positive effects on turnover rate of digesta and feed intake in Holstein cows.     

Effect of soybean oil availabilities on rumen biohydrogenation and duodenal flow of fatty acids in beef cattle fed a diet with crude glycerine

Soybean oil with different ruminal availability (whole soybeans (WS), soybean oil (SO) and calcium salts (CS)) was used to evaluate the fatty acid (FA) intake, rumen biohydrogenation (BH) and duodenal flow of FA in Nellore steers fed diets with crude glycerine (CG). Eight castrated Nellore steers were fitted with a ruminal and duodenal silicone cannula, and distributed in a double, simultaneous, Latin square 4 × 4 design with four diets and four experimental periods. Concentrates contained ground maize, urea, mineral salts, CG (100 g/kg DM) and soybean products with different availability of soybean oil: (1) no additional fat (CO), (2) WS, (3) SO or (4) CS. Fat supplementation was fixed to obtain 50 g ether extract/kg DM. Experimental treatments had no effect on DM intake, DM duodenal flow or ruminal turnover rate of C:16 FA. However, fat addition increased C:18 and turnover rates of total FA rumen (p < 0.05). CS resulted in lower C:18 turnover rates and lower ruminal BH of monounsaturated and unsaturated FA (UFA) than WS (p < 0.05). SO resulted in a greater duodenal flow of C18:0 (stearic acid), C18:1t-11 (vaccenic acid) and saturated FA than the WS and CS diets (p < 0.05). CS resulted in a higher duodenal flow of C18:3n-3 (linolenic acid) than WS (p < 0.05). The association of CG and calcium salts in Nellore steers was the best nutritional strategy to increase duodenal flow of healthier UFA, which may increase the deposition of these FA in meat. However, SO associated with CG association increased the duodenal flow of vaccenic acid, which is main precursor of endogenous synthesis of conjugated linoleic acids in tissues.     

Studies on the biotin flow at the duodenum of dairy cows fed diets with different concentrate levels and types of forages

Abstract

Biotin is involved in many vital metabolic pathways and must be provided for an efficient fermentation in the rumen, as well as for the intermediary metabolism of the host animal. Factors influencing ruminal biotin metabolism and output are widely unknown at present. Therefore, dairy cows fitted with permanent cannulas in the dorsal rumen and in the proximal duodenum were fed differently composed diets, and the biotin flow at the proximal duodenum was measured. The diets (on DM basis) consisted of 8.9 kg grass hay (Diet 1), 8.9 kg corn silage plus 2.0 kg concentrate (Diet 2), or 7.3 and 7.4 kg grass silage plus 10.0 kg concentrate (Diets 3 and 4). The concentrate in Diets 3 and 4 contained 87% wheat and corn grain, respectively. The cows were pre-fed the rations for 21 days. Thereafter duodenal digesta was sampled every two h for 5 days. Cr₂O₃ served as a flow marker and the microbial proportion of total nitrogen at the duodenum was estimated by near infrared spectroscopy (NIRS). The duodenal flow of biotin was not related to biotin intake, but to the amount of fermented organic matter (FOM) and the amount of microbial protein (Biotin [mg/d] = 0.518 · kg FOM?0.300; r = 0.85 and biotin [mg/d] = 0.012 · g microbial protein + 1.478; r = 0.84), irrespective of the composition of the diet fed. Mean daily biotin flow was 0.48 ± 0.11 mg/kg FOM without any systematic effect of diet composition. The ruminal biotin balance, calculated as the difference between biotin flow at the duodenum and biotin intake, was positive (1.4 – 2.0 mg/d) in cows fed the mixed roughage/concentrate diets and negative (?0.71 mg/d) when the pure hay diet was fed.     

Kadmium — Antimetabolit des Eisens und Zinks

The aim of the present dose response study was to examine the long-term effects of increasing the amounts of rare earth elements (REE) in the diet on growth and slaughtering performance of fattening bulls. A total of 48 bulls of German Holstein with an average initial live weight (LW) of 119 ± 13 kg were divided into four dietary treatment groups (n = 12): a control group and three REE-treated groups, which were fed a supplement of 100, 200 and 300 mg REE-citrate per kg dry matter (DM) containing mainly cerium (57.9%), lanthanum (34.0%) and praseodymium (6.5%). The feeding trial was divided into a growing period for 8 weeks and a fattening period for 39 weeks. The growing diet consisted of concentrate, grass silage and grass hay, while the fattening diet consisted of concentrate and maize silage. The animals were slaughtered at approximately 556 kg LW. The intake of grass hay and maize silage (0.55–0.31 kg/d and 6.09–5.44 kg/d, respectively) decreased linearly (p < 0.05) with increasing REE-citrate supplementation, while LW gain showed only a numerical decrease during the growing (2–4%) and the fattening period (4–5%). The feed-to-gain ratio and ME-to-gain ratio were not significantly affected by REE treatment during the whole feeding trial. The most striking effect of REE on carcass characteristics was a significantly higher dressing percentage in Group C (200 mg REE citrate kg/DM) compared to the other groups, while no effects were found on liver, kidneys, heart, thymus, pancreas, spleen and thyroid gland weights. The digestibility trials with wethers indicate that a supplementation of 300 mg REE-citrate per kg DM to a ration consisting of concentrate and straw does not enhance the digestibility of nutrients. These results suggest that, under the conditions of the present study, the supplementation of fattening bull diets with REE cannot be recommended.     

Function of Tongue-Playing of Cattle in Association With Other Behavioral and Physiological Characteristics

To study the function of tongue-playing of cattle, this study observed 71 Japanese Black × Holstein steers after feeding in 2 repetitive experiments. The number of steers who performed tongue-playing did not differ among the 3 levels of environmentally enriched pens. Most (90.6%) performances of tongue-playing terminated within 20 min. Frequency of tongue-playing positively correlated with the frequency of resting (r = 0.25, p < .05). Frequency of eating was lower in tongue-playing steers (n = 40) than in non-tongue-playing steers (n = 31; p < .05). Frequencies of self-grooming (p < .05), ruminating (p < .05), and lying ruminating (p < .01) were higher in tongue-playing steers. Plasma dopamine concentration was lower in tongue-playing steers (p < .05). In conclusion, tongue-playing that lasts only for a short time after feeding was induced by behavioral features of steers who rest more and eat hay less at the same time as they perform grooming and ruminating.     

Rumen microbes and microbial protein synthesis in Thai native beef cattle fed with feed blocks supplemented with a urea–calcium sulphate mixture

The influence of slow-release urea ( urea–calcium sulphate mixture; U–CaS) in feed blocks on rumen micro-organisms, predominant cellulolytic bacteria, microbial protein synthesis and ecology was studied in Thai native beef cattle. Four animals with an initial body weight of 100 ± 3.0 kg were randomly assigned to a 4 × 4 Latin square design with four dietary treatments (U–CaS in iso-nitrogen feed blocks at 0, 120, 150 and 180 g/kg dry matter (DM), respectively; U–CaS replaced urea). After 21 days of experimental feeding, rumen fluid was collected at 0 and 4 h after feeding. The mean intake of feed blocks and other feedstuffs offered (rice straw and concentrates) amounted to 0.3, 2.3 and 0.6 kg DM/day, respectively. Inclusion of U–CaS did not altered pH and temperature in the rumen. However, ruminal NH₃–N concentration decreased quadratically (p < 0.05) in response to U–CaS inclusion, with the lowest value at 180 g U–CaS per kg feed block. With inclusion of U–CaS, the populations of rumen bacteria increased quadratically (p < 0.05) and counts of fungal zoospores were linearly enhanced (p < 0.05), being highest at 180 g U–CaS per kg feed block. Supplementation of U–CaS increased the concentration of total bacteria linearly (p < 0.05) and of Fibrobacter succinogenes quadratically (p < 0.05), whereas Ruminococcus flavefaciens and Ruminococcus albus were not affected by dietary treatments. Microbial crude protein yield and efficiency of microbial nitrogen (N) synthesis were linearly increased with different levels of U–CaS addition. Furthermore, current data clearly indicate that inclusion of U–CaS in feed blocks can affect micro-organism diversity and major cellulolytic bacteria.     

Effects of the dietary ratio of ruminal degraded to undegraded protein and feed intake on intestinal flows of endogenous nitrogen and amino acids in goats

This study was conducted to evaluate the effects of the dietary ratio of ruminal degraded protein (RDP) to ruminal undegraded protein (RUP) and the dry matter intake (DMI) on the intestinal flows of endogenous nitrogen (N) and amino acids (AA) in goats. The experiment was designed as a 4 × 4 Latin square using four ruminally, duodenally and ileally cannulated goats. The treatments were arranged in a 2 × 2 factorial design; two ratios of RDP to RUP (65:35 and 45:55, RDP1 and RDP2, respectively) and two levels at 95% and 75% of voluntary feed intake (DMI1 and DMI2, respectively) were fed to the goats. There were no significant differences in the N intake, duodenal flow of total N, undegraded feed N, microbial N, endogenous N or ileal flow of endogenous N, but the duodenal and ileal flow of endogenous N numerically decreased by approximately 22% and 9%, respectively, when the feed intake changed from DMI1 (0.63 kg/d) to DMI2 (0.50 kg/d). The dietary ratio of RDP to RUP had significant effects (p < 0.05) on the ileal flows of endogenous leucine, phenylalanine and cysteine. The present results implied that the duodenal flows of endogenous N and AA decreased when the dietary RDP to RUP ratio and DMI decreased, and the flow of endogenous AA at the ileum also decreased when the DMI decreased but increased with decreasing RDP to RUP ratios.     

A study on feeding ammoniated and processed barley to feedlot steers

A total of 120 commercial crossbred steer calves (284±1.9 kg) were allocated in a 2×2 arrangement to two barley processing methods; whole (W) or rolled (R) barley and two ammoniation treatments; ammoniated (A) or non-ammoniated (N) barley. Steers were randomly allocated to twelve pens with 10 steers per pen and 3 pens (replications) per diet. The study was divided into two stages, growing (0–84 day) and finishing (85–196 day). Average daily gain (ADG) for the overall 196 day period was affected by processing (p<0.01) averaging 1.10 and 1.20 kg day⁻¹ for steers on W and R barley, respectively. Steers on the R barley gained 19.6% more than those on W barley during the growing stage and 0.8% more during the finishing stage. There was a trend towards an improvement (p=0.06) in overall ADG by ammoniation. The ADG of steers was significantly higher (p<0.01) during the finishing (1.22 kg day⁻¹) than during the growing (1.06 kg day⁻¹) stage. Feed efficiency was better with R than with W barley (6.8 vs. 7.7; p=0.02). Processing and ammoniation had no effect (p>0.05) on carcass traits or grades.     

Addition of citrus pulp and apple pomace in diets for dogs: influence on fermentation kinetics,digestion, faecal characteristics and bacterial populations

Fermentation kinetics, digestibility, faecal characteristics and bacterial populations (aerobes, anaerobes, lactobacilli, lactic acid bacteria, enterococci, coliforms and clostridia) of dog food mixed with citrus pulp and apple pomace were evaluated. The in vitro gas production of a pre-digested dog food mixed with 0, 30, 50 and 70 g/kg dry matter (DM) of citrus pulp or apple pomace was measured, and also an experiment with dogs fed the same dog food with or without the addition of 70 g/kg of either fresh citrus pulp or apple pomace was conducted. Gas production increased linearly (p < 0.001) and quadratically (p < 0.001) as fibre levels augmented. The inclusion of fibre sources in the diets resulted in higher faecal output (p = 0.005) and defecation frequency (p < 0.001), and lower faecal pH (p < 0.001) and digestibility values (p < 0.01). Faecal consistencies and microbial populations did not differ among treatments. The addition of fresh citrus and apple was effective to stimulate the hindgut fermentation, but slightly depressed the digestion.     

Effects of dietary supplementation of rumen-protected folic acid on rumen fermentation,degradability and excretion of urinary purine derivatives in growing steers

The present experiment was undertaken to determine the effects of dietary addition of rumen-protected folic acid (RPFA) on ruminal fermentation, nutrient degradability, enzyme activity and the relative quantity of ruminal cellulolytic bacteria in growing beef steers. Eight rumen-cannulated Jinnan beef steers averaging 2.5 years of age and 419 ± 1.9 kg body weight were used in a replicated 4 × 4 Latin square design. The four treatments comprised supplementation levels of 0 (Control), 70, 140 and 210 mg RPFA/kg dietary dry matter (DM). On DM basis, the ration consisted of 50% corn silage, 47% concentrate and 3% soybean oil. The DM intake (averaged 8.5 kg/d) was restricted to 95% of ad libitum intake. The intake of DM, crude protein (CP) and net energy for growth was not affected by treatments. In contrast, increasing RPFA supplementation increased average daily gain and the concentration of total volatile fatty acid and reduced ruminal pH linearly. Furthermore, increasing RPFA supplementation enhanced the acetate to propionate ratio and reduced the ruminal ammonia N content linearly. The ruminal effective degradability of neutral detergent fibre from corn silage and CP from concentrate improved linearly and was highest for the highest supplementation levels. The activities of cellobiase, xylanase, pectinase and α-amylase linearly increased, but carboxymethyl-cellulase and protease were not affected by the addition of RPFA. The relative quantities of Butyrivibrio fibrisolvens, Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes increased linearly. With increasing RPFA supplementation levels, the excretion of urinary purine derivatives was also increased linearly. The present results indicated that the supplementation of RPFA improved ruminal fermentation, nutrient degradability, activities of microbial enzymes and the relative quantity of the ruminal cellulolytic bacteria in a dose-dependent manner. According to the conditions of this experiment, the optimum supplementation level of RPFA was 140 mg/kg DM.     

Utilization of alkali-treated grain. 2. Utilization by steers of diets based on hay or straw and mixed with either NaOH-treated or rolled barley

In the first of three experiments, Hereford cross steers were fed ad libitum from 325 kg to slaughter at 425 kg on diets containing 50% hay and 50% rolled or NaOH-treated (30 g/kg) barley. Liveweight gain and food conversion ratios were similar for the two groups (1.24 vs. 1.42 kg/day; 7.0 vs. 7.0 kg dry matter intake/kg gain, respectively). Dry matter and organic matter digestibility was significantly higher (P < 0.01) when the diet contained rolled, rather than NaOH-treated, barley. There were no significant differences in fibre digestibility (51.2 vs. 59.1%, respectively).In the second experiment, the optimum level of NaOH was determined for the treatment of barley when given with hay. The level of NaOH required to achieve a digestibility in whole barley similar to rolled barley was 40 g NaOH/kg, i.e., approximately 10 g/kg more than when NaOH-treated barley formed the sole component of the diet. Dry matter and organic matter digestibility increased linearly as the level of NaOH applied increased (P < 0.05) and tended to peak at 40 g NaOH/kg barley. Starch digestibility also increased linearly (P < 0.001). Fibre digestibility did not vary significantly between treatments.In the third experiment, the voluntary intake of straw by steers given rolled or NaOH-treated barley at two levels of supplementation was determined. The intake of straw was slightly, but not significantly, greater when NaOH-treated rather than rolled barley was used. The digestibility of dry matter, organic matter, starch and fibre was not significantly affected by method of cereal treatment. No problems of animal health arose throughout the three experiments.     

Response of urinary purine derivatives excretion to different levels of ruminal glucose infusion in heifers

This study investigated the response of urinary purine derivatives (PD) excretion to increasing levels of intraruminal glucose infusion to evaluate how well this indicator reflects induced changes in microbial crude protein flow. Four rumen-cannulated heifers (482 ± 25 kg body weight) were fed at maintenance energy level with a basal diet (on fresh matter basis) of 4 kg/d hay, 1.5 kg/d concentrate and 60 g/d minerals in two equal meals. The trial comprised a control period (Control I) without glucose infusion followed by four consecutive periods in which all animals received 125 g, 250 g, 500 g or 1000 g/d of glucose, respectively. For this, daily dosages of glucose and urea (90 g/d during all periods) were divided into three portions that were dissolved in water and directly administered into the rumen during morning and afternoon feedings and once during noon. After the highest glucose dosage, a second control period was carried out (Control II). Urinary PD excretion increased with glucose infusion of 125 g/d (71.4 mmol/d) and 1000 g/d (74.2 mmol/d) over the level at Control I (53.9 mmol/d (standard error of the mean (SEM) 3.4; p = 0.012). After withdrawing glucose infusion, PD excretion (79.0 mmol/d) did not return to Control I level (p = 0.001). In contrast, faecal nitrogen (N) excretions linearly increased with incremental glucose infusion (p < 0.001) from 33.9 g/d at Control I to 39.7 g/d (SEM 0.5) at 1000 g/d of glucose and were similar in Control I and II (p = 0.086). The contradicting responses in the excretions of faecal N and urinary PD to increasing glucose infusions highlight the limited accuracy of the PD excretion as a non-invasive indicator when incremental dosages of rapidly fermentable carbohydrates are supplied.     

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.     

The impact of divergent breed types and diets on methane emissions,rumen characteristics and performance of finishing beef cattle

This study was undertaken to further develop our understanding of the links between breed, diet and the rumen microbial community and determine their effect on production characteristics and methane (CH₄) emissions from beef cattle. The experiment was of a 2×2 factorial design, comprising two breeds (crossbred Charolais (CHX); purebred Luing (LU)) and two diets (concentrate-straw or silage-based). In total, 80 steers were used and balanced for sire within each breed, farm of origin and BW across diets. The diets (fed as total mixed rations) consisted of (g/kg dry matter (DM)) forage to concentrate ratios of either 500 : 500 (Mixed) or 79 : 921 (Concentrate). Steers were adapted to the diets over a 4-week period and performance and feed efficiency were then measured over a 56-day test period. Directly after the 56-day test, CH₄ and carbon dioxide (CO₂) emissions were measured (six steers/week) over a 13-week period. Compared with LU steers, CHX steers had greater average daily gain (ADG; P<0.05) and significantly (P<0.001) lower residual feed intake. Crossbred Charolais steers had superior conformation and fatness scores (P<0.001) than LU steers. Although steers consumed, on a DM basis, more Concentrate than Mixed diet (P<0.01), there were no differences between diets in either ADG or feed efficiency during the 56-day test. At slaughter, however, Concentrate-fed steers were heavier (P<0.05) and had greater carcass weights than Mixed-fed steers (P<0.001). Breed of steer did not influence CH₄ production, but it was substantially lower when the Concentrate rather than Mixed diet was fed (P<0.001). Rumen fluid from Concentrate-fed steers contained greater proportions of propionic acid (P<0.001) and lower proportions of acetic acid (P<0.001), fewer archaea (P<0.01) and protozoa (P=0.09), but more Clostridium Cluster XIVa (P<0.01) and Bacteroides plus Prevotella (P<0.001) than Mixed-fed steers. When the CH₄ to CO₂ molar ratio was considered as a proxy method for CH₄ production (g/kg DM intake), only weak relationships were found within diets. In conclusion, although feeding Concentrate and Mixed diets produced substantial differences in CH₄ emissions and rumen characteristics, differences in performance were influenced more markedly by breed.     

Effects of nanosized zinc oxide and γ-polyglutamic acid on eggshell quality and serum parameters of aged laying hens

In order to increase zinc (Zn) absorption and improve eggshell quality, diets for aged laying hens were supplemented with different Zn sources and the effects on egg production, eggshell quality and serum parameters were recorded. Seventy-five 64-week old brown layers were individually caged and randomly allotted to five treatment groups: an un-supplemented Control and four groups, where the following Zn sources were added to the diets, ZnO (group ZnO), Zn-methionine (group Zn-Met), nanosized ZnO (group nanoZnO) and γ-PGA-nano ZnO (group γ-PGA-nanoZnO). The Zn level was maintained at 80 mg/kg in the supplemented diet, while the Control group received Zn at 40 mg/kg diet. The results indicated that the average daily feed intake was highest in group nanoZnO (p < 0.05), whereas further performance parameters were not influenced by treatments. Eggshell thickness was increased in group γ-PGA-nanoZnO (p < 0.05). Zn content in eggshells and Zn concentration in serum were increased in groups Zn-Met, nanoZnO and γ-PGA-nanoZnO (p < 0.05). Serum ghrelin concentration was significantly elevated in all Zn-supplemented groups, but further increased in groups nanoZnO and γ-PGA-nanoZnO (p < 0.05). Carbonic anhydrase activity was highest in group γ-PGA-nanoZnO and lowest in group Zn-Met (p < 0.05). Compared to the Control and group ZnO, supplementation of γ-PGA-nanoZnO and nanoZnO increased serum IgG levels (p < 0.001). In conclusion, dietary supplementation of nanoZnO and γ-PGA-nanoZnO increased Zn content in eggshells, serum Zn concentration, ghrelin and IgG levels of aged layers when compared to regular ZnO. Compared to Zn-Met, the serum carbonic anhydrase activity and ghrelin levels were also increased. Thus, nanosized ZnO alone or mixed with γ-PGA has positive effects on the Zn status of aged layers.