Effects of dung beetle activity on the number of nematode parasites acquired by grazing cattle.

Parasitized steers were used to contaminate 3 pastures containing dung beetle populations of different densities. Six parasite-free calves were then allowed to graze the pastures for 43 to 45 days. Two calves that grazed a pasture with dung beetle population rendered lower than normal by screening and trapping acquired 9 times more parasites than 2 calves that grazed a pasture which captured beetles were released. Two calves that grazed a pasture with a natural dung beetle population acquired 4 times more worms than the calves on pasture with the increased beetle population. The results indicated that the 2 major genera of nematodes present (Ostertagia and Cooperia) were significantly reduced in number by dung beetle activity.     

Winter Resistant Oocysts in the Pasture as a Source of Coccidial Infection in Lambs

Lambs born in pens with slatted floor were brought out at 2–5 weeks of age on pastures heavily grazed by sheep the previous years. About 16 days later the oocyst output of the lambs rapidly increased to high levels. Lambs on pastures which never had been grazed by sheep earlier, had moderate oocyst counts. Between 11 and 25 days after the beginning of grazing there were significantly more lambs with diarrhoea on permanent pastures compared with pastures never grazed by sheep earlier. It was found that lambs were heavily infected during the first 2 days on permanent pastures. Thirteen housed lambs were given 10–50 g of soil from a permanent pasture as a water suspension by a stomach tube. Fifteen days later there was a steep rise in the oocyst output in most of them, and 11 of the 13 lambs developed diarrhoea and 2 died. None of 10 lambs given uninfected soil and none of 12 untreated controls showed diarrhoea and the oocyst output remained on a moderate level. It is concluded that oocysts which have survived the winter in the pasture are the main source of infection with Eimeria spp. in lambs with this kind of management. Soil-eating is the most likely source of infection during the first days on pasture.     

Effects of avermectin residues in cattle dung on yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae) populations in grazed pastures

The effects of avermectin exposure on natural populations of the yellow dung fly, Scathophaga stercoraria Linnaeus, were investigated at the field scale on farms in south-west Scotland. Pastures forming the focus of the study were grazed with either untreated cattle or cattle receiving standard, manufacturer-recommended treatment regimes of an avermectin product. Flies were sampled between April and July in 2002 and 2003 using dung-baited pitfall traps. Abundance and wing asymmetry in S. stercoraria populations were examined in relation to a range of environmental and management variables (including avermectin exposure, pasture management intensity, weather and season). Data used for abundance analyses were collected in fields where treated cattle had been dosed with either doramectin or ivermectin, while the data for the asymmetry analyses were from a subset of fields where treated cattle had been dosed with doramectin only. While abundance of S. stercoraria varied significantly between years and with season, there was no difference in their abundance between fields grazed by avermectin-treated or untreated cattle. Asymmetry was significantly higher in fly populations in fields grazed by doramectin-treated cattle, suggesting that exposure to doramectin during development could have imposed some degree of environmental stress. While these results suggest that exposure to doramectin residues in dung on grazed pastures may have sublethal effects on the insects developing in that dung, there was no evident avermectin effect on the abundance of adult S. stercoraria occurring in the pastures.     

Seroresponse (IgG) after Vaccination and Natural Infection of Cattle with Babesia Divergens

The antibody response against Babesia divergens in vaccinated calves and in unvaccinated sentinels on farms where vaccination had been practiced routinely, was investigated using a live vaccine. Sera were obtained before and 3 weeks after vaccination in March and April, approximately 1 month before the animals were put out on pasture. Additional blood samples were collected at the end of the grazing season and again the next spring. At that time previously unvaccinated sentinel calves were vaccinated and their antibody response was tested 3 weeks later. All sera were analysed by an IF-technique. All of the vaccinated calves (100%) were seropositive 3 weeks after vaccination. The seroresponse did not differ signifacantly between animals vaccinated before their first or second grazing season although the age difference was about 12 months. No clinical symptoms of babesiosis were seen in vaccinated animals. The titres were, however, significantly higher 3 weeks after vaccination than 6 months later. After the grazing season about 42% of the unvaccinated sentinel calves were sero–positve. Two of these calves had clinical babesiosis on pasture in July and September respectively. The number of sentinel calves which became infected on pasture showed a large farm-to-farm variation although all cattle on the farms once had been infected-/vaccinated with B. divergens. Probably the different number of calves infected was a reflection of a variation in tick density on the different pastures. All calves, which were seropositive after the grazing season, were also seropositive after 6 months indoors. The titres declined during the winter period, but they were still within the range of 2 doubling dilution steps.     

The Dynamics, Prevalence and Impact of Nematode Infections in Organically Raised Sheep in Sweden

A three-year survey (1997–99) was carried out on organically reared sheep flocks throughout Sweden. The aim was to determine the prevalence and intensity of nematode infections and to establish relationships between sheep management practices and parasite infections. Faecal samples from ewes and lambs were collected from 152 organic flocks around lambing-time and during the grazing-period for analysis. Results were compared with the different management practices that farmers use to prevent parasitism in their flocks. A high proportion of the flocks was infected with nematodes. The most prevalent species were Haemonchus contortus, Teladorsagia circumeincta, Trichostrongylus axei, T. colubriformis and Chabertia ovina and infections progressively increased during summer in lambs grazing on permanent pastures. Severity of parasitic infection in lambs was highly dependent on egg output from the ewes. H. contortus was found in 37% of the flocks, even at latitudes approximating the Polar Circle. Nematodirus battus was recorded for the first time in Sweden during the course of this study. Lambs turned out onto permanent pasture showed higher nematode faecal egg counts (epg) than lambs that had grazed on pastures, which had not carried sheep the previous year. This beneficial effect of lambs grazing non-infected pastures persisted if the ewes were treated with an anthelmintic before turn-out and if the lambs were kept on pastures of low infectivity after weaning. In lambs, the prevalence and the magnitude of their egg counts were higher during autumn in flocks where lambs were slaughtered after 8 months of age, compared with flocks where all lambs were slaughtered before this age. These results will be used in providing advice to farmers of ways to modify their flock management in order to minimise the use of anthelmintics, but at the same time efficiently produce prime lambs.     

The role of parasite epidemiology in the management of grazing cattle

Epidemiology of ruminant helminths is the foundation on which strategic parasite control programmes are designed. Without this information one is not able to use anthelmintics to provide the optimal benefits for controlling both the adult worm and the pasture larval populations. The absence of strategic programmes generally results in using anthelmintics at the convenience of the producer, which may have little if any impact on parasite populations. The design of a strategic parasite control programme requires a knowledge of the dynamics of egg shedding from the host and the resulting pasture larval populations. It is important to know if larvae are available when animals are turned out onto pasture, when larval populations reach their maximal numbers and when they are induced to become hypobiotic. The goal is to keep pasture larval populations as low as possible. The use of pasture rotation adds another dimension to control programmes. The longer a pasture is allowed to remain fallow, the lower the pasture larval burden will be when it is grazed next. However, when we use intensive rotational grazing, animals may return to the pasture about 28 days later, when the larvae resulting from the eggs shed in the previous grazing are infective. This practice forces cattle to eat all of the forage available, including the grass closest to the faecal pat, where most of the infective larvae are available. If we treated cattle before turning them onto a clean rotationally grazed pasture, we should be able to control parasitism. Using a long-acting anthelmintic should enhance helminth control in rotationally grazed pastures and actually help to clean the pastures. Another grazing management practice is to alternately graze different species. This programme with the strategic use of anthelmintics should reduce parasitism in both host species.     

Control of nematode parasites by grazing management—I. Decontamination of cattle pastures by grazing with sheep

Between December and June, six paddocks that had been contaminated naturally with infective larvae of nematode parasites of cattle, were each subjected to one of six grazing treatments. The effects of these treatments on the infectivity of the pastures were assessed by slaughter and total worm counts of calves which subsequently grazed the paddocks, and by counts of larvae on pasture samples. Grazing by sheep during autumn resulted in reduced populations of Ostertagia ostertagi and Trichostrongylus axei, both in calves and on the pasture for up to 12 months after treatment. Similar effects were noted on pasture grazed by cattle repeatedly dosed with anthelmintics, and on ungrazed pasture. There was little effect of any treatment on numbers of Cooperia oncophora. It was concluded that the level of autumn contamination was of importance in determining the numbers of O. ostertagi in the following spring and summer.     

Efficacy of Monensin Against Bovine Coccidiosis in Young Holstein-Friesian Calves*

Monensin, an anticoccidial antibiotic, was incorporated into pelleted feed and given to 10-week-old Holstein-Friesian calves at 0.25 mg/kg, 1.0 mg/kg, or 2.0 mg/kg of body weight. Inoculated calves were inoculated by drenching with 500,000 sporulated oocysts of Eimeria bovis. Other calves served as inoculated or uninoculated controls. Observations were recorded on oocyst discharge in the feces, clinical signs, weight gain, food consumption, hemoglobin, packed cell volume, total serum protein, sodium and potassium content of the serum, and differential white cell counts. Calves in the inoculated control group developed severe infections, discharged large numbers of oocysts, developed clinical signs and 1 of 5 died. Uninoculated, untreated control calves were essentially free of coccidia. A few calves in the groups which received monensin developed light infections but none of them had clinical signs of coccidiosis. Calves which received the highest and the lowest dosages of monensin gained weight less rapidly than did the uninoculated controls or the animals which received monensin at 1.0 mg/kg of body weight. Inoculated control calves with severe infections had reduced food intake and a significant reduction in weight which was not regained during the experimental period. The only other significant change in any of the parameters measured was a reduction in the total serum protein of inoculated, nonmedicated control calves. The level returned to normal 5 weeks after clinical signs first appeared.     

Fecal and Molecular Survey of Neospora caninum in Farm and Household Dogs in Mashhad Area, Khorasan Province, Iran

Neospora caninum is an important cause of abortion in dairy cattle worldwide. Dog is the definitive host for N. caninum and can infect dairy cattle. The aim of this study is to determine the prevalence of Neospora oocysts in feces of dogs from dairy farms. A total of 174 fecal samples was collected from 89 farm dogs and 85 household dogs during 2006 and 2008. Fecal samples of dogs were microscopically examined for detecting Hammondia Neospora-like oocysts (HNLO) by Mini Parasep®SF fecal parasite concentrator. HNLO were microscopically detected in 4 fecal samples (2.2%). The fecal samples with HNLO were examined by N. caninum-specific PCR. Two of the samples were positive for N. caninum. The 2 positive fecal samples were selected for inoculation to calves. Two inoculated calves were seronegative by ELISA for 4 months post-infection. This is the first report of finding N. caninum DNA in feces of farm dogs in Mashhad area, Iran.     

Control of nematode parasites by grazing management—II. Decontamination of sheep and cattle pastures by varying periods of grazing with the alternate host

Commencing in December 1970, paddocks of a uniform series of sheep pastures were grazed for 6, 12 or 24 weeks by either yearling steers is or yearling ewes. Cattle pastures were treated similarly. All ewes and steers were pre-dosed with anthelmintic.At the conclusion of alternate grazing the effectiveness of the grazing treatments was evaluated by grazing each paddock for 1 month with either ten worm-free lambs (sheep pastures) or three wormfree calves (cattle pastures). The test animals were then slaughtered for total worm counts. The grazing of sheep pastures with cattle for 6, 12 or 24 weeks from December onwards resulted in reductions in numbers of Haemonchus contortus and Trichostrongylus colubriformis in test lambs. In comparison with continuous grazing by sheep, Nematodirus spp was only reduced after 24 weeks grazing by cattle. Cattle pastures grazed by sheep for 6 weeks showed no reduction in numbers of Ostertagia ostertagi or Cooperia oncophora in test calves. However after 12 weeks with sheep, numbers of O. ostertagi though not C. oncophora were reduced and after 24 weeks of alternate grazing both these species were reduced.Calves following the 6 week sheep treatments acquired both Haemonchus contortus and Trichostrongylus colubriformis and the calves from the 12 week sheep treatment paddock also carried H. contortus. For sheep the only evidence of cross-transmission was the occurrence of small numbers of Cooperia oncophora in test lambs from the 24 week cattle grazing treatment.The results provide evidence that sequential stocking with cattle and sheep in conjunction with anthelmintic treatment is an effective management strategy for preparing parasitologically safer pastures, but further information is required to determine the optimum timing of sequential stocking in farming situations.     

Horses grazing with cattle have reduced strongyle egg count due to the dilution effect and increased reliance on macrocyclic lactones in mixed farms

Strongyle infection is an important issue in horse breeding. It impairs horse health and performance, with young horses being the most sensitive. Strongyle control has long relied on the systematic use of chemical treatments. However, expanding anthelmintic resistance among strongyles calls for alternative options. Mixed grazing is assumed to reduce strongyle load on the pasture as the result of a dilution effect. This has been shown in small ruminants grazing with cattle, but the putative benefits of co-grazing between horses and cattle have not yet been evaluated. Here, we conducted field surveys and face-to-face interviews on 44 farms from two contrasted saddle-horse production areas, Normandy and northern Massif Central, to compare equine strongyle management practices between specialized systems and mixed horse-cattle systems. Our goals were (i) to quantify breeders’ awareness of the putative benefits associated with the co-grazing of horses and cattle, (ii) to establish whether mixed farming was associated with different strongyle management strategies and (iii) to test whether strongyle egg excretion was reduced in horses grazed with beef cattle. Every breeder relied on systematic calendar treatments, and only 8 out of the 23 mixed breeders were aware that co-grazing of horses with cattle could be used as part of their strongyle control strategy. Management practices were similar across both systems in Normandy. In Massif Central, mixed breeders formed a distinct cluster from their specialized counterparts: deworming was less frequent and stocking density was higher in mixed farms, while specialized breeders seemed more willing to integrate herd and plot management into control strategies. Faecal egg counts measured in horses from Massif Central were significantly reduced when horses were grazed with cattle. This was the result of an increased reliance on macrocyclic lactones in mixed farms (P < 0.01) and a significant dilution effect (P < 0.01). When considering a subsample of horses treated with macrocyclic lactones only, young horses grazed with cattle had 50% fewer strongyle eggs excreted in their faeces than horses grazed in equine-only pastures (P < 0.01). This is the first evidence of the benefits of mixed grazing with cattle as an alternative to control strongyle infection in horses, although this promising alternative remains largely unknown by horse breeders.     

The development and overwintering survival of free-living larvae of Haemonchus contortus in Sweden

Five complimentary studies were undertaken with the overall aim to examine the ability of free-living stages of Haemonchus contortus to over-winter and tolerate cold stress. Two studies deal with the development and long-term survival of eggs and infective larvae of two geographically different isolates (Kenya and Sweden). Eggs and larvae were monitored in climatic chambers at temperatures that fluctuated daily between -1 degrees C and 15 degrees C, or at constant temperatures of 5 degrees C and 15 degrees C. The development from egg to larvae was dependent on temperatures over 5 degrees C. The long time survival was favoured at lower temperatures. Furthermore, the overwintering capacity of the free-living stages of these isolates was estimated under Swedish field conditions. Two groups of lambs were experimentally infected with different isolates, and kept separated on previously ungrazed plots. In early May the following year, two parasite-naive tracer lambs were turned out on each of the plots to estimate the pick up of overwintered larvae. This experiment was replicated in central and southern Sweden. In addition, two experiments were performed in 2003 on pasture previously grazed by naturally infected sheep. One trial was on a pasture in southern Sweden grazed by a commercial flock, where extreme numbers of H. contortus were found towards the end of the grazing season 2002. The other study was on a pasture plot in central Sweden grazed by a hobby flock in 2002, where three of six lambs died due to haemonchiasis. Overwintered H. contortus was recorded on three of four experimental sites. Worm burdens were in all instances extremely low. No differences in development and survival were found between the isolates. Consequently, overwintering on pasture is of no practical significance in the transmission of H. contortus between grazing-seasons in Sweden.     

Observations on parasitic gastroenteritis and bronchitis in grazing calves: effect of low level feed incorporation of morantel in early season.

Pott J. M., Jones R. M. and Cornwell R. I. 1979. Observations on parasitic gastroenteritis and bronchitis in grazing calves: effect of low level feed incorporation of morantel in early season. International Journal for Parasitology9: 153–157. Twenty-four castrated Friesian calves were divided into two equal groups on a body weight basis and grazed separate halves of an infected pasture. One group was given 1.5 mg/kg per day morantel tartrate in the feed over a period extending from 2 weeks before turning out in early May to early July. The other group of calves received an equivalent amount of unmedicated food as controls. Pasture larval counts showed a similar pattern and level of infection from February to July on both pastures. This consisted of a fall from moderate winter levels to very low levels in April/July. The control pasture then showed a typical sharp rise in August to high levels extending through September and falling to moderate levels in October. The pasture being grazed by treated calves showed only a small rise in larval counts in August. The total pasture contamination was reduced by 85% compared with controls during August/October. Faecal egg and larval counts showed similar differences between treated and control calves. Mild clinical signs of parasitic gastroenteritis and bronchitis were seen in controls but not in the treated group. The latter had a weight gain advantage of 20.5 kg the difference becoming marked in the last month of the trial.     

Peripartal Excretion of Eimeria Oocyst by Cows on Swedish Dairy Farms and the Age of Calves at First Excretion

Faecal samples were collected 3 times a week for 6 weeks from 22 peripartal cows and for up to 15 weeks after birth from 27 calves in 3 herds, to determine the numbers of Eimeria oocysts excreted and the age at which the calves first excreted oocysts. Only low numbers of oocysts were excreted by the cows and no oocysts were detected in 93% of the samples. However, half the cows excreted oocysts at least once. The age at which the calves first excreted oocysts ranged from 2.5 to at least 15 weeks, and there was a significant difference between the herds in their mean age at first excretion. Oocysts of Eimeria alabamensis, E. auburnensis, E. bovis and E. ellipsoidalis were found in numbers ranging from 7 to 8450 oocysts per gram faeces. About 50% of the calves excreted oocysts before they were transferred to group pens. The primary source of infection of the calves was probably their penmates or the previous occupants of the pens, and the cows probably played a subsidiary role.     

Effects of experimental infection with Eimeria bovis on the balance of sodium, potassium and water in calves

Balance trials were performed to investigate the effects of experimental Eimeria bovis coccidiosis on the metabolism of water, sodium and potassium in calves. Non-infected pair-fed controls and controls fed according to plan were included in the study to allow differentiation between the effects due to infection and due to changes in feed intake. Primary infection with 5 × 10⁴ (group A) or 1 × 10⁵ (group B) oocysts caused mild diarrhoea in three out of four group A calves and mild to severe haemorrhagic diarrhoea in all five group B calves. Losses of sodium and potassium via faeces tended to increase in the infected calves during patency and apparent digestibility (AD) of these minerals was comparably low. In the urine of the infected calves the Na/K-ratio decreased due to a reduced urinary excretion of sodium. The retention (RT) of sodium was particularly high in the calves that had received the higher oocyst dose. Potassium RT did not underlie significant changes during the course of coccidiosis. In the infected calves the plasma level of sodium was reduced transiently while the level of potassium remained fairly stable. Infections with the higher oocyst dose caused a distinct reduction of fluid excretion via urine which compensated for the increased faecal water losses during severe diarrhoea. Reinfection of the group A calves with 1 × 10⁵ oocysts did not cause any significant metabolic impairment. The results of this study indicate that although acute sublethal bovine coccidiosis alters electrolyte and water metabolism the overall balance of electrolytes and water is largely maintained by physiologic adaptation.     

Plant biodiversity on shortgrass steppe after 55 years of zero,light, moderate,or heavy cattle grazing

Shortgrass steppe rangeland near Nunn, Colorado, USA, has been lightly,moderately, or heavily grazed by cattle, or protected from grazing inexclosures, for 55 years. Plant species biodiversity and evenness were greatestin lightly- and moderately-grazed pastures. Both pastures weredominated by the warm-season shortgrass Boutelouagracilis, but the cool-season midgrasses Pascopyrumsmithii and Stipa comata contributedsignificantly to biomass production on the lightly-grazed pasture, asthey did in the exclosures. Diversity was least in the exclosures, which werestrongly dominated by the cactus Opuntia polyacantha.Buchloë dactyloides, another warm-seasonshortgrass, and Bouteloua gracilis were co-dominantsunder heavy grazing, and diversity was intermediate. Plant community structureand diversity were controlled by selective grazing by cattle and soildisturbance by cattle and rodents. Shortgrass steppe moderately or heavilygrazed by cattle was similar to and probably as sustainable as steppe grazed formillenia by bison and other wild ungulates.     

The influence of weather and egg contamination on the development of third-stage larvae of Cooperia oncophora on pasture.

The influence of weather and egg contamination on the dynamics of herbage contamination with infective larave of Cooperia oncophora was investigated on artificially contaminated grass plots and in a grazing experiment with 24 first-year grazing calves from May to October 1987 in Lower Saxony, Germany. On the experimental plots the larval translation was highest at the beginning of July and in the second part of September, following high mean weekly temperatures. Between July and September peak recovery of larvae from herbage occurred 4 weeks after contamination. A seasonal pattern of larval translation similar to that on the experimental plots could be demonstrated on the grazed pastures when the number of larvae per m2 of pasture had been adjusted to the previous egg output by means of a contamination index. The resulting 'relative larval density' is regarded as a good indicator for larval development on pasture. From July to September the larval population on pasture resulted mainly from the egg contamination 2-3 weeks earlier. The short persistence of the infective larvae on herbage was probably due to the frequent and heavy rainfall throughout the season, causing a passive washout of larvae into the soil. On single pastures the larval density started to increase within 1 week after the calves had first contact with these fields. The impact of the calves on the distribution of larvae is discussed.     

Effect of rainfall on biomass,growth and dieback of pastures in an arid grazing system

The influence of rainfall and initial pasture biomass on growth and dieback of pastures in temporary enclosures over quarterly periods was examined from 1980 to 1985 at Menindee in western New South Wales. Rainfall during the previous 12 months had the most influential effect on biomass of grazed pasture, and accounted for 69% of the variance. During quarterly periods, when the biomass of pasture protected from grazing increased, rainfall accounted for 93% of the variance. For all quarterly periods (whether pasture biomass increased or decreased) current rainfall accounted for 72% of the variance in biomass change (growth minus senescence) and initial biomass accounted for a further 14%. The growth response to rainfall was similar in pastures grazed by a combination of sheep and kangaroos and in those grazed by kangaroos alone.     

Effects of social learning on foraging behaviour and live weight gain in first-season grazing calves

When livestock are turned out to semi-natural grasslands, an effective onset of grazing is important both for animal productivity and for defoliation of the sward, which preserve the biodiversity of the vegetation. The aim of this study was to investigate whether foraging behaviour of naïve calves turned out to pasture was more intense, with a resulting diminished live weight loss, when experienced cattle accompanied them acting as social models. Twenty-six first-season grazing (FSG) dairy calves, allocated to groups with or without company of older, grazing-experienced steers, were turned out to semi-natural grasslands. Cattle behaviour was automatically recorded for 24 h during the first day on pasture and during 24 h after 1 month. Furthermore, the average live weight changes for the first day and for the first month on pasture were calculated. Calves turned out to pasture accompanied by grazing-experienced steers had similar grazing times (on average 42.7% of the day) to calves turned out to pasture in groups without older steers, but they had higher grazing activity during the first day on pasture (score 124 vs. 99, P = 0.005). Live weight changes were similar in calves kept with as in calves kept without company of grazing-experienced steers (?4.60 kg for the first day and ?0.30 kg day^?1 for the first month on pasture). In conclusion, the company of grazing-experienced conspecifics resulted in higher grazing activity in naïve calves, but their time spent grazing and live weight gains were unmodified. Hence, in this limited study we found no major positive effects on production of using grazing-experienced cattle as company to FSG calves on semi-natural grasslands.     

Biological Control of Sheep Parasites using Duddingtonia flagrans: Trials on Commercial Farms in Sweden

   

Trials were conducted on 3 commercial sheep farms in Sweden to assess the effect of administering spores of the nematode trapping fungus, Duddingtonia flagrans, together with supplementary feed to lactating ewes for the first 6 weeks from turn-out on pastures in spring. Also control groups of ewes, receiving only feed supplement, were established on all 3 farms. Groups were monitored by intensive parasitological investigation. The ewes and their lambs were moved in late June to saved pastures for summer grazing, the lambs receiving an anthelmintic treatment at this time. After approximately 6 weeks on summer pasture the lambs were weaned, treated a second time with anthelmintic, and returned to their original lambing pastures for finishing. Decisions as to when lambs were to be marketed were entirely at the discretion of the farmer co-operators. No difference in lamb performance was found between the two treatments on all three farms. This was attributed to the high levels of nutrition initially of the ewes limiting their post-partum rise in nematode faecal egg counts in spring, which in turn resulted in low levels of nematode infection on pastures throughout the autumn period. Additionally, pastures were of good quality for the lambs during the finishing period, so they grew at optimal rates as far as the farmers were concerned.