Polyethylene glycol marker measured with NIRS gives a reliable estimate of the rangeland intake of grazing sheep

Polyethylene glycol (PEG) measured with NIRS is known to be a valuable faecal marker when used in indoor experiments. In order to verify whether it can be used at pasture, an experiment was conducted with two trials. In trial 1, six Romane breed adult dry ewes placed in metabolism cages were fed daily with natural, freshly cut rangeland from a fertilised or unfertilised paddock for 6 weeks. Three ewes did not receive PEG and the three others were dosed with 10 g of PEG in solution form once daily until the end of the experiment to measure in vivo dry matter digestibility and PEG recovery rate for each forage quality. At the same time (trial 2), 15 ewe lambs and 14 lactating adult ewes suckling one or two lambs were allowed to graze together on the same herbage as that cut for indoor ewes. All animals were initially equipped with faecal bags emptied twice daily for collecting total faeces, and eight ewe lambs and seven adults were dosed once daily with 10 g of PEG. Faecal grab samples were collected for 4 to 5 days for each forage quality grazed. Indoor trial 1 showed that PEG had no effect on dry matter intake (DMI) or on digestibility. PEG recovery rates measured on fertilised (77.7%) and unfertilised (82.1%) forage were not different (P>0.05). PEG recovery rates measured at pasture did not differ (P>0.05) between pasture quality and animal type with an average value of 68.9%. Faecal output measured with bags or estimated with PEG and calculated DMI were not different (P>0.05) when PEG recovery rate measured at pasture was used. Conversely, using indoor PEG recovery values, significantly (P<0.05) or tended to overestimate faecal output. In conclusion, PEG could be used as a faecal marker administered at a minimal dose of 1% of DMI with a recovery rate measured under pasture conditions for pasture intake measurements on a group of animals at the same physiological stage but not for individual measurements.     

Polyethylene glycol compared with ytterbium oxide as a total faecal output marker to predict organic matter intake of dairy ewes fed indoors or at pasture

Several external markers can be used for estimating total faecal output in view of assessing ruminant intake at pasture. Among them, ytterbium (Yb) has been used for many years in various conditions. Polyethylene glycol (PEG) is a promising external marker because it can be rapidly determined using near-infrared spectroscopy (NIRS). The study consisted of 24 adult lactating dairy ewes over three periods (P1, P2 and P3), fed with three different diets: P1, total mixed ration (TMR); P2, Italian ryegrass (IRG); and P3, pasture. After an adaptation period, the ewes were administered a daily dose of ytterbium oxide (0.35 g/day) and PEG (20 g/day) for 2 weeks. During the last week, the daily organic matter intake (OMI_OBS) was measured. Faecal samples were collected at milking time (0800 and 1600 h) to determine marker content, using only samples collected in the morning (PEG_m) or by averaging samples (Yb, PEG_ma). Faecal marker content made it possible to assess total faecal output, either using the two recovery rates for PEG (0.98 or 0.87) or not. The OMI_OBS was assessed on the basis of total faeces estimated with Yb (OMI_Yb) or PEG (OMI_PEG), and the digestibility was calculated on the basis of feed analysis. With total TMR (P1), the OMI_PEG, corrected with recovery rate (OMI_PEGm98) or not corrected (OMI_PEGm) was 2.40 kg/day and 2.50 kg/day, respectively, and was not different (P>0.05) from OMI_OBS (2.51 kg/day), whereas OMI_Yb was lower (2.14 kg/day) (P<0.001). With IRG (P2), OMI_PEGm98 (1.67 kg/day), OMI_PEGm87 (1.51 kg/day) and OMI_Yb (1.59 kg/day) were not different (P>0.05) from OMI_OBS (1.57 kg/day). With pasture (P3), the OMI_PEGm (1.54 kg/day) and OMI_PEGm98 (1.48 kg/day) were not different (P>0.05) from the OMI assessed from the biomass measurement (1.52 kg/day). The OMI_Yb (1.36 kg/day) was lower (P<0.05) but not different from OMI_PEGm98 and OMI_PEGm87. Spearman’s rank correlation between OMI_OBS and other OMIs (predicted with Yb or PEG P1 and P2) showed that it is possible to rank animals using PEG when there is a sufficiently wide range of OMI_OBS (1.65 to 2.8 kg/day in P1) but not within a narrower range (1.47 to 1.72 kg/day in P2). In conclusion, the present study confirms that PEG is a valuable external faecal marker, easy to prepare (solution), administer and determine (NIRS). It can be used to assess intake with numerous animals at pasture, but only for groups, and not to quantitatively estimate individual OMI.     

Ovarian consequences of low dose peroral Fusarium (T-2) toxin in a ewe and heifer model

The effect of low dose peroral Fusarium produced T-2 toxin intake upon the ovarian function was evaluated in ewes (n = 30; Trial 1) and heifers (n = 7; Trial 2). Half of the ewes and all of the heifers were fed rich, acidosis-inducing concentrate. The 30 ewes were divided into 6 groups of 5 animals each. They were given 0, 0.3 or 0.9 mg/day (0, 5 or 15 ug/kg) purified T-2 toxin per os for 21 days (3x2 factorial design). Four of the 7 heifers were fed 9 mg/day (25 ug/kg) of the same purified T-2 toxin for 20 days while 3 remained untreated. The estrus cycles in all animals were synchronized prior to the trials and the T-2 exposure was started in the mid-luteal phase. The acidic condition in the rumen was estimated by the determination of urinary net acid-base excretion. The ovarian activity was followed with blood sampling for progesterone on alternate days (Trial 1) or with ultrasonography and sampling for progesterone daily (Trial 2). All of the heifers and concentrate-fed ewes showed a compensated acidosis, during first two thirds of T-2 exposure. In Trial 1, ovarian malfunction manifested as lower P4 peak concentration in the midluteal phase, shortening of the CL lifespan and prolonged follicular phases. These malfunctions were detected in 3 and 3 ewes fed concentrate and 0.3 mg and 0.9 mg T-2 toxin. Lower P4 peak concentration was observed in 1 ewe fed regular diet and 0.9 mg T-2 toxin. None of the control and acidotic groups (0 mg T-2), or ewes fed regular diet with 0.3 mg T-2 showed any ovarian malfunction. In Trial 2, after PGF2, administration the ovulation occured later and the plasma progesterone level remained low (< 3 nmol/l) for a longer period in T-2 treated heifers, than their untreated control mates (5.0+/-0.7 vs 3.7+/-0.5 d, P<0.05 and 8.3+/-0.4 vs 6.3+/-0.9 d, P<0.01, respectively). These results show that the peroral T-2 intake can significantly retard the folliculus maturation and ovulation and perhaps the subsequent luteinisation also in ruminants kept on concentrate-rich diet.     

Reproductive performance of Coopworth ewes following oral doses of zearalenone before and after mating

The reproductive performance of Coopworth ewes after administration of zearalenone was determined in two trials. In Trial I, zearalenone was administered to groups of 33 ewes at rates of 0, 1.5, 3.0, 6.0, 12.0 and 24.0 mg/ewe/day for 10 days, starting on Day 7 of the oestrous cycle before mating. There was a linear decline (P less than 0.001) in ovulation rate with dose of zearalenone; also cycle length decreased and duration of oestrous increased with increasing dose levels. Reductions in the incidence of ovulation and in fertilization were seen only at doses of 12 and 24 mg. In Trial 2, groups of 50 ewes were given the same range of doses of zearalenone for 10 days, starting 5 days after mating to entire rams. There was no effect of zearalenone treatment after mating on pregnancy rate or embryonic loss. These results indicate that the effects of zearalenone, administered orally, on ewe reproduction, at the dose levels examined, were restricted to ewes exposed before mating. Intakes of zearalenone of 3 mg/ewe/day or more during this period would be reflected as depressed ovulation rates and lower lambing percentages.     

Sleep and circadian phase in a ship's crew

Numerous factors influence the increased health risks of seamen. This study investigated sleep (by actigraphy) and the adaptation of the internal clock in watch-keeping crew compared to day workers, as possible contributory factors. Fourteen watch keepers, 4 h on, 8 h off (0800-1200/2000-2400 h, 1200-1600/2400-0400 h, 1600-2000/0400-0800 h) (fixed schedule, n = 6; rotating by delay weekly, n = 8), and 12 day workers participated during a voyage from the United Kingdom to Antarctica. They kept daily sleep diaries and wore wrist monitors for continuous recording of activity. Sleep parameters were derived from activity using the manufacturer's software and analyzed by repeated-measures ANOVA using SAS 8.2. Sequential urine samples were collected for 48 h weekly for 6-sulphatoxymelatonin measurement as an index of circadian rhythm timing. Individuals working watches of 1200-1600/2400-0400 h and 1600-2000/0400-0800 h had 2 sleeps daily, analyzed separately as main sleep (longest) and 2nd sleep. Main sleep duration was shorter in watch keepers than in day workers (p < 0.0001). Objective sleep quality was significantly compromised in rotaters compared to both day workers and fixed watch keepers, the most striking comparisons being sleep efficiency (percentage desired sleep time spent sleeping) main sleep (p < 0.0001) and sleep fragmentation (an index of restlessness) main sleep (p < 0.0001). The 2nd sleep was substantially less efficient than was the main sleep (p < 0.0001) for all watch keepers. There were few significant differences in sleep between the different watches in rotating watch keepers. Circadian timing remained constant in day workers. Timing of the 6-sulphatoxymelatonin rhythm was later for the watch of 1200-1600/2400-0400 h than for all others (1200-1600/2400-0400 h, 5.90 +/- 0.85 h; 1600-2000/0400-0800 h, 1.5 +/- 0.64 h; 0800-1200/ 2000-2400 h, 2.72 +/- 0.76 h; days, 2.09 +/- 0.68 h [decimal hours, mean +/- SEM]: ANOVA, p < 0.01). This study identifies weekly changes in watch time as a cause of poor sleep in watch keepers. The most likely mechanism is the inability of the internal clock to adapt rapidly to abrupt changes in schedule.     

Effects of shortened daylength and melatonin treatment on plasma prolactin and melatonin levels in pinealectomised and sham-operated ewes

Comparisons have been made between the effects of shortened daylength and melatonin treatment on plasma prolactin and melatonin levels in pinealectomised (Px) and sham-operated (Sh) ewes. Twenty-two anoestrous Merino crossbred ewes, maintained under normal grazing conditions, were assigned to four groups for a period of 9 weeks. Group 1 remained untreated (control), Group 2 was herded into a dark shed at 1600 h each day until dark (approx 4 h), ewes in Group 3 were injected with 100 μg melatonin s.c. at 1600 h each day and ewes in Group 4 were implanted with a melatonin capsule releasing 125–200 μg/day. Another group (Group 5) of 4 Px and 4 Sh ewes from the same flock was maintained in an animal house and subjected to shortened daylength (10. 5 h L : 13. 5 h D, lights off 1600 h). Three weeks after the treatments began, ewes in Groups 1–4 were exposed to a fertile ram and ewes in Group 5 to a vasectomised ram and the day of mating noted. No differences were evident between Groups 1–4 in the ewes' response to the ram, time taken to conceive, duration of gestation or number of lambs born. In untreated Px ewes no plasma melatonin (< 20 pg/ml) was found in either day or night samples, whereas intact animals showed the characteristic night-time rise. The silastic implants produced stable daytime blood levels of 90–120 pg/ml, whereas a single injection of 100 μg melatonin caused a transitory (2–3 h) rise. Shortened daylength (Group 2) or a single daily injection of melatonin (Group 3) lowered prolactin levels but only in ewes with an intact pineal gland, whereas melatonin implants (Group 4) caused a reduction in plasma prolactin in both Px and Sh sheep. The results indicate that light-induced alterations in prolactin production in sheep involve both the pineal gland and melatonin. Continuous melatonin release from implants caused changes in plasma prolactin levels similar to those seen following exposure to short days.     

The effect of clenbuterol on time of lambing and neonatal death loss

Two experiments were conducted to test the ability of clenbuterol, a beta-sympathomimetic agonist, to delay lambing. Ewes in all experiments were induced to lamb with 2.5 mg of flumethasone given intramuscularly on Day 141, 142 or 143 of gestation. Beginning on the day of flumethasone administration and continuing daily until lambing, ewes in Experment 1 were given injections intramuscularly (i.m.) with either 1) vehicle solution at 2200 h, 2) 240 ug of clenbuterol at 2200 h or 3) 240 ug of clenbuterol at 1600 and at 2200 h. There was a greater proportion of ewes lambing between 0800 h and 1600 h (P<0.01) and more stillbirths (P=0.05) in the groups which received clenbuterol than in the vehicle control group. Experiment 2 was conducted to determine if a lower dosage of clenbuterol, given as a single injection 37 h after flumethasone, would delay lambing without increasing the proportion of stillbirths. Ewes received either the vehicle solution, or 36 or 146 ug of clenbuterol. Lambing was delayed in the group which received 146 ug but not 36 ug of clenbuterol. There were no adverse effects of treatment on lamb survival in Experiment 2.     

Nutritive value of lentil and vetch straws as compared with alfalfa hay and wheat straw for replacement ewe lambs

The objective of this study was to compare the nutritive value of lentil straw (LS) and vetch straws (VS) with alfalfa hay (AH) and wheat straw (WS). Forty Awassi ewes (body weight (BW)=56.2 kg) were assigned randomly to four dietary treatments (10 ewes per treatment) for 6 weeks using a complete randomize design. In each dietary treatment, ewes were fed 550 g per day of concentrate mix formulated to supply 40% of the metabolizable energy requirement. After the consumption of the concentrate mix, ewes had ad libtum access to AH, LS, VS, or WS. Forage intake, total dry matter intake (DMI), and organic matter intake (OMI) were higher for AH and LS and lowest for WS. Final weight of ewes fed AH and LS diets were higher (P<0.05) than VS and WS diets. However, ewes fed VS diet gained more weight (2.5 kg) than ewes on WS diet (0.2 kg). Dry matter digestibility was higher for the AH and LS diets (59.4%), and lowest for WS diet (49.6%). The VS diet had an intermediate value (54.4%). Ruminal passage rate was higher for AH and LS (3.4% per hour) compared with WS (1.9% per hour). Eating time for the AH diet was lowest compared with the rest of the forages. Eating time, expressed as minutes per kilogram NDF intake, was highest for WS and VS diets (680 min) compared with AH and LS diets (535 min). WS diet required more time for rumination (395 min per day) compared to AH, LS, and VS diets. However, ewes on VS diet spent more time ruminating per kilogram NDF consumed (954 min) compared with WS, LS, and AH diets (901, 617, and 597 min, respectively). These results were significant and demonstrate that the nutritive value of LS is greater than VS and close to the nutritive value of AH. VS nutritive value is slightly greater than WS.     

Effect of stage of maturity of grass at harvest on intake,chewing activity and distribution of particle size in faeces from pregnant ewes

This study was conducted to investigate the effect of stage of maturity at harvest on the intake of grass silage, eating and ruminating activity and the distribution of faecal particle size in ewes during late pregnancy. A total of 18 Swedish Finull × Dorset 85 ± 8 kg (mean ± s.d.) ewes bearing twins were randomly assigned to three dietary treatments 6 weeks before lambing. The treatments included ad libitum feeding with early harvested (EH), medium harvested (MH) or late harvested (LH) primary-growth grass silage with 45%, 58% and 63% NDF on a dry matter (DM) basis, respectively. Intake and chewing activity were recorded and faeces were sampled over 4 continuous days for each individual ewe. The faeces samples were washed in nylon bags, freeze dried and sieved with pore sizes from 2.4 mm to 0.1 mm; particles less than 0.1 mm in size were also collected. Subsamples of each sieving fraction were scanned and the dimensions of the individual particles in each sieving fraction were measured by image analysis. In addition, the number of particles longer than 7 mm was counted from the particles retained on a sieve with a pore size of 2.4 mm using a simple wet sieving technique. The time spent eating and ruminating per kg of DM intake was affected by the stage of maturity at harvest; it was shorter in ewes fed EH compared with ewes fed MH and LH (P < 0.05). In comparison with feeding LH, feeding EH resulted in the retention of a larger proportion of particles in the lower and upper sieve fractions (<0.2 mm and >1 mm, respectively, P < 0.01), a smaller mean particle size (P < 0.05) and a smaller mean particle width in faeces (P < 0.01). The results from the simple wet sieving technique confirmed the results from dry sieving and image analysis, showing a higher number of large particles in faeces from ewes fed the EH compared with the ewes fed the MH and LH (P < 0.001). In conclusion, the distribution of faecal particle size might be considered as a footprint of the characteristics of forage fibre eaten by ewes.     

Effects of replacing grass silage with either maize silage or concentrates during late pregnancy on the performance of breeding ewes fed isonitrogenous diets

A study was undertaken to investigate the performance of breeding ewes fed a range of forage and concentrate-based diets in late pregnancy, balanced for supply of metabolizable protein (MP). For the final 6 weeks before lambing, 104 twin-bearing multiparous ewes were offered one of four diets: ad libitum precision-chop grass silage + 0.55 kg/day concentrates (GS); ad libitum maize silage + 0.55 kg/day concentrates (MS); a 1 : 1 mixture (on a dry matter (DM) basis) of grass silage and maize silage fed ad libitum + 0.55 kg/day (GSMS); or 1.55 kg/day concentrates + 50 g/day chopped barley straw (C). The CP content of the concentrates was varied between treatments (157 to 296 g/kg DM) with the aim of achieving a daily intake of 130 g/day MP across all treatments. Compared with ewes fed GS, forage DM intake was higher (P < 0.05) in ewes fed MS (+0.21 kg/day) and GSMS (+0.16 kg/day), resulting in higher (P < 0.001) total DM intakes with these treatments. C ewes had the lowest total DM intake of all the treatments examined (P < 0.001). C ewes lost more live weight (LW; P < 0.001) and body condition score (BCS; P < 0.05) during the first 3 weeks of the study but there were no dietary effects on ewe LW or BCS thereafter. The incidence of dystocia was lower (P < 0.01) in C ewes compared with those offered silage-based diets (7.5% v. 37.4% ewes), and was higher (P < 0.01) in ewes fed MS compared with GS or GSMS (50.7%, 34.7% and 26.9%, respectively). There were no significant dietary effects on the plasma metabolite concentrations of ewes in late pregnancy, pre-weaning lamb mortality, weaned lamb output per ewe or on lamb growth rate. The results of this study demonstrate that both maize silage and all-concentrate diets can replace grass silage in pregnant ewe rations without impacting on performance, provided the supply of MP is non-limiting. The higher incidence of dystocia in ewes fed maize silage as the sole forage is a concern.     

Timing of a single daily meal and diel variations of serum thyroxine,triiodothyronine and cortisol in goldfish carassius auratus

Two groups of goldfish were maintained on a 12L:12D photoperiod at 19°C and fed either at 0800 (light onset) or 1600 h daily. After 3 weeks, blood samples were taken at one of six times of day and the serum was analyzed for thyroxine, triiodothyronine, and cortisol by radioimmunoassay. Fish fed in the morning had significant diel variations in circulating titers of thyroxine and cortisol, those fed in the afternoon had significant variations of thyroxine and triiodothyronine. Meal feeding appeared to entrain, and phase shift, the cortisol rhythm but not the rhythms of thyroid hormones. These results are briefly discussed in light of the effects of timing the daily meal on weight gain in fish.     

The effect of fish oil supplementation of pregnant and lactating ewes on milk production and lamb performance

Supplementation of pregnant ewes with long-chain n-3 polyunsaturated fatty acids (PUFA) demonstrably improves indicators of neonatal lamb vigour, potentially improving the number of lambs reared per ewe. The present study investigated the effect of supplementing ewes with fish oil and vitamin E (α-tocopherol acetate) throughout both pregnancy and lactation on the performance of lactating ewes and sucking lambs. Forty-eight ewes were supplemented with one of four concentrates containing either Megalac or fish oil plus a basal (50 mg/kg) or supranutritional (500 mg/kg) concentration of vitamin E from 6 weeks pre-partum until 4 weeks post partum in a two-by-two factorial randomised-block design. All concentrates were formulated to contain approximately 60 g/kg supplemental fatty acids. Ewes were housed, penned on sawdust and offered straw ad libitum. Blood samples were taken from ewes and lambs at intervals throughout the experiment and milk samples were obtained at 21 days into lactation. There was no notable effect of dietary vitamin E concentration upon ewe or lamb performance. Ewe dry-matter (DM) intake and yield were unaffected by dietary treatment, although ewes fed fish oil lost less weight during lactation (-1.88 kg compared with -3.97 kg for Megalac-supplemented ewes; P < 0.01). Milk fat concentrations (67.3 g/kg compared with 91.8 g/kg; P < 0.01) and yields (6.65 g/h v. 9.26 g/h; P < 0.01) were reduced in ewes fed fish oil and these decreases were associated with lower litter-growth rates (0.49 g/day compared with 0.54 g/day; P < 0.05). Milk protein yield was increased by fish oil supplementation (3.82 g/h) compared with Megalac supplementation (3.28 g/h; P < 0.05); moreover, there was an interaction between fat source and vitamin E concentration in that both protein concentration and yield were significantly lower in milk from ewes fed treatment with Megalac + basal vitamin E (MB) compared with the other three treatments. Fish oil supplementation increased the concentrations of C18:1 trans-, cis-9, trans-11 conjugated linoleic acid (CLA), C20:5 (n-3) and C22:6 (n-3) within ewe plasma, milk and lamb plasma. The mechanisms by which fish oil supplementation affects milk composition warrants further investigation.     

Predicting feed digestibility from NIRS analysis of pig faeces

Digestibility is a key parameter in the evaluation of feeds; however, the measurements on animals require heavy experimental trials, which are hardly feasible when large numbers of determinations are required – for example, in genetic studies. This experiment aimed at investigating the possibility to predict digestibility from NIRS spectra measured on faeces. A total of 196 samples were available from a digestibility experiment investigating the effects of age and genetic background of Large White pigs fed the same diet, rich in fibre (NDF=21.4% DM). Digestibility of dry matter (dDM), organic matter (dOM), nitrogen content (dN), energy (dE) and apparent digestible energy content (ADE) were calculated, as well as total N content of faeces (N). The faeces samples were submitted to reflectance NIRS analysis after freeze-drying and grinding. Calibration errors and validation errors were, respectively, 0.08 and 0.13% DM for total N in faeces, 0.97% and 1.08% for dDM, 0.79% and 1.04% for dOM, 1.04% and 1.47% for dN, 0.87% and 1.12% for dE and 167 and 213 kJ/kg DM for ADE. These results indicate that NIRS can account for digestibility differences due to animal factors, with an acceptable accuracy. NIRS appears to be a promising tool for large-scale evaluations of digestibility. It could also be used for the study of digestibility of different feeds, after appropriate calibration based on a wide range of feed types.     

Effects of ewes grazing sulla or ryegrass pasture for different daily durations on forage intake,milk production and fatty acid composition of cheese

Sulla (Sulla coronarium L.) forage is valued for its positive impact on ruminant production, in part due to its moderate content of condensed tannin (CT). The duration of daily grazing is a factor affecting the feed intake and milk production of ewes. In this study, the effects of grazing sulla pasture compared with annual ryegrass, and the extension of grazing from 8 to 22 h/day, were evaluated with regard to ewe forage intake and milk production, as well as the physicochemical properties and fatty acid (FA) composition of cheese. During 42 days in the spring, 28 ewes of the Comisana breed were divided into four groups (S8, S22, R8 and R22) that grazed sulla (S) or ryegrass (R) for 8 (0800 to 1600 h) or 22 h/day, and received no feeding supplement. In six cheese-making sessions, cheeses were manufactured from the 48 h bulk milk of each group. Compared with ewes grazing ryegrass, those grazing sulla had higher dry matter (DM) intake, intake rate and milk yield, and produced milk that was lower in fat and higher in casein. Ewes grazing for 22 h spent more time eating, which reduced the intake rate, increased DM and nutrient intake and milk yield, and reduced milk fat. Due to the ability of CT to inhibit the complete ruminal biohydrogenation of polyunsaturated fatty acids (PUFA), the FA composition of sulla cheese was more beneficial for consumer health compared with ryegrass cheese, having lower levels of saturated fatty acids and higher levels of PUFA and n-3 FA. The FA profile of S8 cheese was better than that of S22 cheese, as it was higher in branched-chain FA, monounsaturated FA, PUFA, rumenic acid (c9,t11-C18:2), and had a greater health-promoting index. The effect of short grazing time on sulla was attributed to major inhibition of PUFA biohydrogenating ruminal bacteria, presumably stimulated by the higher accumulation of sulla CT in the rumen, which is related to a higher intake rate over a shorter eating time. Thus, grazing sulla improved the performance of ewes, thereby increasing, especially with short grazing time, the nutritional properties of cheese fat.     

Repeated daily doses do not increase Listeria monocytogenes infection in ewes as shown by faecal excretion and serological monitoring

Ruminants fed contaminated forage may shed Listeria monocytogenes in their faeces, and prolonged low daily doses of L. monocytogenes could cause listerial infection [Maijala, R., Lyytikainen, O., Autio, T., Aalto, T., Haavisto, L., Honkanen-Buzalski, T., 2001. Exposure of Listeria monocytogenes within an epidemic caused by butter in Finland. Int. J. Food Microbiol. 70, 97–109]. To compare listerial infection following single or repeated doses and the contamination of the environment with the excreted bacteria, ewes were orally inoculated with either 10⁴, 10⁶ or 10¹⁰ cfu L. monocytogenes once, or daily for 10 days. Serological responses were monitored with indirect ELISAs using recombinant listeriolysin O (LLO), internalin A (InlA) and internalin A-related protein (IrpA). The 24 inoculated animals displayed no symptoms, except for a transient hyperthermia in two animals given 10¹⁰ cfu. One ewe died on day 9 after non-listerial mastitis followed by listerial septicaemia. L. monocytogenes was recovered from day 1 post-inoculation until day 17 from the faeces of ewes inoculated with 10⁶ or 10¹⁰ cfu. No antibodies were detected in ewes given 10⁴ or 10⁶ cfu. Anti-LLO and anti-IrpA antibodies were detected from day 15 in animals inoculated with 10¹⁰ cfu, and this strengthened the conclusion that these long-lasting shedders were infected but asymptomatic carriers. An anti-InlA response was detected only at a very low level. These results suggest that repeated daily doses are no more effective than a single dose in causing infection in ewes.     

Reproductive response and LH secretion in ewes treated with melatonin implants and induced to ovulate with the ram effect

Two experiments were conducted to examine the effects of treating seasonally anoestrous ewes with melatonin before ram introduction on reproductive response, and on LH secretion in anoestrous ewes induced to ovulate by rams.In Experiment 1, a total of 667 ewes from three flocks involving Merino (Flock 1, N = 149), Merino entrefino (Flock 2, N = 325) and Rasa Aragonesa (Flock 3, N = 203) breeds were used. Within each flock, ewes isolated from rams since the previous lambing were assigned at random to receive melatonin implants of Regulin (75, 175 and 105 in Merino, Merino entrefino and Rasa Aragonesa flocks, respectively) or to serve as untreated controls (74 in Merino, 150 in Merino entrefino and 98 in Rasa Aragonesa flocks). Fertile rams were introduced into all flocks 5 weeks after implantation in March (Flocks 1 and 2) or April (Flock 3), and remained with the ewes for a 50 day mating period. Percentage of ewes with luteal activity at ram introduction did not differ between melatonin treated and control ewes in any flock. There were no significant differences in either the mean interval from ram introduction to lambing or the distribution of lambing. Implantation with melatonin resulted in an improvement of prolificacy in all three flocks, although this only reached statistical significance in the Merino flock (1.15 vs. 1.03 in treated and control ewes, respectively, P < 0.05). Fertility was increased significantly (P < 0.05) in the Merino entrefino flock (64.5% in treated vs. 51.3% in control ewes).In Experiment 2, two trials were undertaken utilizing a total of 63 ewes. Trial 1 involved 24 mature Manchega ewes and Trial 2 involved 39 Merino ewe lambs. Half of the animals in each trial received a Regulin implant on 28 February (Trial 1) or 12 March (Trial 2) and the remaining half acted as controls. Rams were introduced 5 weeks after implantation and remained with the ewes for a 25 day period. In both trials, anoestrous ewes at ram introduction were bled at 20 min intervals for 3 h before and 5 h after ram introduction and then at 3 h intervals over the next 24 h for assessment of plasma concentrations of LH. Secretion of LH before or following introduction of rams was not affected by melatonin. Both treated and control anoestrous ewes in each trial responded to introduction of rams with an increase in the frequency of the LH pulses (P < 0.05), but no significant changes were detected in pulse amplitude or mean levels of LH. A preovulatory surge of LH was detected between 8 and 26 h after ram introduction, but neither mean interval from ram introduction to the peak of LH surge, nor the magnitude of the LH peak, was influenced by melatonin treatment.Results from this study show that: (1) melatonin implants administered during early seasonal anoestrus have the potential to improve reproductive performance in Spanish breeds of sheep, but the response is conditioned by breed, management system and environmental factors; (2) melatonin did not modify the secretion of LH in anoestrous ewes induced to ovulate by the ram effect under our experimental conditions.     

Amelioration in Growth and Phosphorus Assimilation of Poultry Birds Using Cell-Bound Phytase of Pichia Anomala

Summary Cell-bound phytase of Pichia anomala was produced in glucose–beef extract medium in shake flasks and in a laboratory fermenter at 25 °C for 24 h at 250 rev/min. In the fermenter the biomass production increased and the fermentation time was reduced from 24 to 16 h. Two-week-old broiler chicks were fed with the biomass-supplemented feed [at 100 g/7.5 kg; 50-phytase units/bird/day]. The overall weight gain in the biomass-fed chicks was higher (90.2%) than that of the control group (77.7%). The biomass incorporation in the feed of broiler chicks also resulted in a better phosphorus retention (29% in the control, and 73.68% in the biomass-fed) in the body, consequently an improved growth. There was a decrease in the excretion of phosphorus in the faeces of the chicks fed with phytase-supplemented diet (188.9 mg/g dry matter) as compared to the chicks fed on unsupplemented broiler finisher ration (509.4 mg/g dry matter). This eliminated the need to supplement phosphorus in their diet and also reduced phosphorus pollution. The feed conversion ratio was also lowered for chicks, which were biomass-fed as compared to the control.     

Effect of concentrate feeding sequence on equine hindgut fermentation parameters

Feeding a diet with a small amount of hay and a high proportion of concentrate given in large meals entails a risk of colic to horses as this can impact the hindgut microbial ecosystem. To counteract this potential negative effect, one feeding strategy is to modify the distribution sequence of concentrate and hay. The purpose of the present study was to assess the impact of feeding the concentrate meal before or with the hay meal on fermentative parameters postprandial variations in caecum and right ventral colon contents and faeces. We focused on the comparison of pH value and volatile fatty acid (VFA) concentrations between the three compartments. Four horses fitted with two cannulas in the caecum and right ventral colon were fed a 100% hay diet (H) for a 3-week period, and then a 40% concentrate–60% hay diet for two consecutive periods of 3 weeks each. Concentrate and hay were offered simultaneously in two equal meals at 0800 and 1700 h (HC1) during one period, or separately in two equal meals at 0800 and 1600 h for the concentrate and at 1000 and 1730 h for hay (HC2) during the second one. During the 2^nd week of each diet period (H, HC1, HC2), caecal, right ventral colonic and faecal samples were collected before (0) and at 2, 4, 6 and 8 h after the morning meal. pH values and VFA concentrations were measured. Adding concentrate to the hay was associated with a decrease of pH value in the caecum, right ventral colon and faeces and an increase of faecal VFA concentrations (P<0.01). An impact of the concentrate feeding sequence was observed on caecal pH and faecal propionate concentration (P<0.001) but none on the other parameters investigated. In the caecum and right ventral colon, pH values decreased and VFA concentrations increased within the range of 4 to 8 h after the morning meal. Our data suggested that the variation of faecal pH could be an indicator of those of the caecal and right ventral colonic pH with a delay of 2 h. The present study showed that hay and commercial pelleted could be safely distributed simultaneously, thus making easier every day horse feeding.     

Pattern of ovarian progesterone secretion during the luteal phase of the ovine estrous cycle

Pulsatile secretion of progesterone has been observed during the late luteal phase of the menstrual cycle in the rhesus monkey and human. As the luteal phase progresses in each of these species, there is a pattern of decreased frequency and increased amplitude of progesterone pulses. The present study was designed to determine the pattern of progesterone secretion during the late luteal phase (Days 10-16) of the normal ovine estrous cycle. Five unanesthetized ewes, each bearing an indwelling cannula in the utero-ovarian vein, were bled every 15 min from 0800 h on Day 10 through 0800 h on Day 16 of the estrous cycle. With the computer program PULSAR, it was determined that progesterone secretion was episodic, with pulsations observed on all days. Analysis of variance was used to determine differences in frequency, amplitude, and interpeak interval (IPI) of progesterone pulses among ewes and days. The ewes averaged 8.0 +/- 0.63 pulses of progesterone per 24 h. Mean frequency of pulses was not different between days but showed differences between ewes. Mean amplitude of progesterone pulses was 7.0 +/- 0.27 ng/ml, with no differences observed either between days or between ewes. Mean IPI was 197 +/- 7.1 min, and, like frequency, the IPI was not different between days, but varied between ewes. No consistent temporal relationship was found between progesterone pulses and luteinizing hormone (LH), as determined by bioassay and radioimmunoassay, on Day 14 of the cycle in one ewe. The results indicate that progesterone secretion is episodic during the luteal phase of the ovine estrous cycle and is independent of LH pulses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sulfur and methionine metabolism in sheep. I. First approximations of sulfur pools in and sulfur flows from the reticulo-rumen.

Sulfur pools in the rumen and sulfur flows from the rumen were investigated in two experiments with sheep on a diet containing equal parts of oaten and lucerne chaffs. The diet was fed at two levels, either chopped or pelleted, and with intraruminal DL-methionine supplements. Ruminal fluid volumes and fluid flows to the omasum were measured. None of the treatments influenced ruminal fluid volume. Fluid flow to the omasum, however, was increased by increasing dry matter intake (DMI), and was further enhanced by feeding chaffed hay rather than the same materials ground and pelleted; the DL-methionine supplement had no effect. First approximation of the ruminal sulfur pools and of sulfur flows to the omasum were derived from the concentration of sulfur in true digesta and the ruminal fluid volume or fluid flow. Increasing DMI from 500 to 1000 g/day resulted in larger ruminal pools of total (1096 v. 792 mg), neutral (1016 v. 731 mg) and protein (479 v. 419 mg) sulfur, but the reducible sulfur pools were not affected by the level of DMI. Infusions of DL-methionine increased the ruminal sulfide sulfur pool irrespective of level of DMI. The first approximation of total sulfur flow was increased by 1660 mg/day at the higher level of DMI, due mainly to increases of 710 mg S/day as protein sulfur and 859 mg S/day as non-protein neutral sulfur. Flows of inorganic sulfate and ester sulfate sulfur, although small in comparison with organic sulfur flows, increased with level of DMI. Sulfide sulfur flows were also increased at the higher level of DMI, and were almost doubled by intraruminal infusions of DL-methionine.