Abomasal parasitism in dairy cows in Belgium

Over a period of one year, from March 1984 to April 1985, the abomasa of 157 dairy cows in East Flanders (Belgium) were collected and examined for the presence of nematodes. Faeces and blood were also collected from the animals. No worms were recovered from 18 cows (11.5%), 118 cows (75%) had a low to moderate worm burden (10-10,000) and 21 cows (13.5%) a high worm burden (greater than 10,000). The geometric mean total number was 2171. Ostertagia ostertagi and Trichostrongylus axei were the main species involved, with the former accounting for 90% of all trichostrongyles recovered. For both worms a seasonal pattern was evident, with the highest worm counts in December-January. Between December and February greater than 97% of the Ostertagia spp. worm burden were EL4. For all animals the average pepsinogen level was 1391 +/- 494 mU tyrosine with no statistically significant relationship between pepsinogen levels and the total number of gastric nematodes. Only 45% of the faeces samples were positive for strongylid eggs with a mean of 43 eggs per gram. The percentage generic composition of L3 larvae collected from faeces was 62% Ostertagia, 18% Trichostrongylus, 6% Cooperia, 4% Oesophagostomum and 0.2% Bunostomum.     

Monthly and seasonal fluctuations in abomasal nematode worm burden of naturally infected cattle in Austria

From October 1980 until September 1981, 191 abomasa of naturally infected cattle were obtained from the slaughter-houses of Mürzhofen and Graz in the province of Styria, and of Wiener Neustadt in the province of Lower Austria and examined to study the monthly and seasonal occurrence of hypobiosis in Ostertagia ostertagi and Trichostrongylus axei. Infections in pastured animals (cows, steers and heifers) were compared with those in stabled animals (bulls fed on green forage and silage). Except for 10 bulls fed on silage all animals were parasitized. The results indicate that in Austria inhibited early fourth stage larvae of Ostertagia accumulate during the winter. Pastured animals showed a higher intensity of infection than stabled animals. Cows less than 3 and greater than 5 years of age had higher worm counts than those between these ages. There was a simultaneous accumulation of third stage larvae and adult worms of Trichostrongylus axei in autumn in steers and heifers. In bulls fed on green forage a higher adult worm burden was seen in winter. No significant correlation existed between the number of worm nodules in the abomasal mucosa and the various developmental stages of the worms. The count of in-utero immature eggs was higher in stabled than in pastured animals. No significant correlation between the number of in-utero eggs and that of female worms was noticeable. Numbers of mature Ostertagia eggs rose in spring, while in fall and winter the immature eggs predominated. An increase in the uterine egg count was observed in Trichostrongylus in autumn. Statistical analyses of our data show that the most decisive factor influencing the numbers of inhibited and adult Ostertagia as well as in-utero eggs is the system of animal management.     

Anthelmintic efficacy of netobimin against naturally acquired gastrointestinal nematodes in yearling heifers

The efficacy of netobimin (Coded SCH 32481, Schering Corporation) in removing naturally acquired gastrointestinal nematode infections was evaluated in 10 treated and 10 untreated (control) yearling beef heifers. The anthelmintic was administered as an oral drench at a dose level of 7.5 mg kg-1 body weight. Fecal egg per gram (EPG) counts were reduced with netobimin by 98% (P less than or equal to 0.01) at both 1 and 2 weeks post-treatment (PT). The compound was highly effective in removing Oesophagostomum radiatum (100% at P less than or equal to 0.01), Cooperia spp. (97.66% at P less than or equal to 0.01) and Nematodirus helvetianus (100%, although not significant), but was ineffective against immature Ostertagia ostertagi (3.19%) and only moderately effective against adult forms (66.14% at P less than or equal to 0.05). The low efficacy against adult O. ostertagi was partially attributed to the maturation of fourth-stage larvae, not removed by the 7.5 mg kg-1 treatment, during the 14-day treatment-slaughter interval. Efficacy against Trichuris spp. could not be evaluated due to low levels and unequal numbers of worms recovered in the groups. The overall efficacy against adult species, excluding Trichuris spp., was 67.40% (P less than or equal to 0.05). No adverse reactions or signs of toxicosis were observed in heifers treated with netobimin.     

Feasibility of genus-specific real-time PCR for the differentiation of larvae from gastrointestinal nematodes of naturally infected sheep

Results of real-time PCR analysis of coproculture third stage larvae (L3) using genus specific TaqMan minor groove binder probes were compared with the results of morphological differentiation of L3 after coprocultured and direct morphological worm differentiation from gastrointestinal samples of eight sheep with naturally acquired nematodes infections. Faecal egg counts prior to postmortem confirmed infections with trichostrongyles with a geometric mean count of 4828 eggs per gram for all sheep. Individual egg counts correlated positively with total worm counts (correlation coefficient 0.794). Five different nematode species and one genus were found in the abomasi and small intestines: Cooperia curticei, Haemonchus contortus, Nematodirus spp., Teladorsagia (Ostertagia) circumcincta, Trichostrongylus axei and Trichostrongylus colubriformis. Coproculture of faecal eggs yielded five of these, Cooperia spp., Haemonchus spp., Ostertagia/Teladorsagia spp. and Trichostrongylus spp. Comparison between morphological L3 and worm differentiation data showed high congruence (94%). The agreement between PCR analysis of L3 after coproculture and direct morphological worm differentiation was 84%. Thus, real-time PCR was found to be suitable as a speedy and reliable diagnostic tool for the assessment of gastrointestinal nematode infections of ruminants in the field.     

Epidemiology and control of bovine ostertagiasis in South America

Gastrointestinal parasitism has been recognized by practitioners as the most common disease in beef cattle, mainly in weaning calves and fattening steers. Among the different genera, Ostertagia ostertagi is the predominant parasite in the temperate climate, in which the major beef and dairy cattle area of South America is situated. Outbreaks of Type I ostertagiasis are usually seen after weaning time (autumn-winter) when larvae counts are high and food availability is low. The development of the disease is rapidly established and 15-30 kg are lost in 30-50 days. Epidemiological studies have demonstrated a fast evolution of parasite eggs to larvae (L3) in summer (1 week or less), evolution being 30-45 days during winter. Inhibition O. ostertagi occurs during spring (September-December) and development resumes in late summer and early autumn. The production effect is seen as a significant reduction in body weight gain and occasionally clinical Type II ostertagiasis appears. A similar epidemiological pattern of inhibition of Ostertagia sp. has been recorded in Uruguay and temperate areas in southern Brazil.     

Survey of helminth infections in Maine dairy cattle.

The survey was done to determine the incidence and seasonal prevalence of the gastrointestinal helminths infecting Maine dairy cattle. Approximately equal groups of calves, heifers, and cows from 13 dairy farms, managerially and geographically representative of dairying in the state, were sampled at regular 2-month intervals over the period of a year. On the basis of fecal egg counts and identification of cultured larvae, the following results were obtained: Of the 94 adult cows, 78 heifers, and 91 calves sampled continuously in the course of the survey, 95.7%, 98.7%, and 96.7%, respectively, were strongylorid positive (infected with Ostertagia, Cooperia, Trichostrongylus, Haemonchus, and Oesophagostomun), with an overall incidence of 97%. Strongyloides papillosus eggs were in 64.6% of the cattle, Bunostomum in 40.3%, Nematodirus in 27.8%, Trichuris in 27.0%, Capillaria in 9.5%, Moniezia in 25.1%, and Dictyocaulus viviparus larvae in 2.7%. Worm burdens, as reflected by mean nematode egg production per gram of feces, varied. The greatest worm burdens were in the calves, followed by the heifers and the cows. A marked variation in egg production related to season was observed, particularly with the strongylorid worms. Peak strongylorid egg production was observed in the May-June sampling period. After the peak period, worm burdens decreased in all groups of cattle to their lowest point during the winter period of January-February. This pattern of egg production was similar to that reported by workers in other parts of the world. Farm management practices were shown to be related to the degree of parasitism existing in these herds. Those herds classed as poorly managed had significantly higher levels of parasitism in young animals than those classed as having fair or good management.     

Effect of Ostertagia ostertagi on lamb performance and cross resistance to O circumcincta

Fifteen worm-free lambs (two-and-a-half to three months or four to four-and-a-half months old) were infected with 3500 or 4000 Ostertagia ostertagi larvae on five days each week for six weeks, and their performance compared to that of controls. Eleven lambs were killed after eight weeks and four were challenged with O circumcincta to determine whether any cross resistance had developed. A feature of the O ostertagi infection was the considerable variation in response. Overall liveweight gain was lowered by 24 per cent in the two-and-a-half to three-month-old infected lambs, mainly due to reductions of 27 to 40 per cent in four of the seven lambs. There was no consistent effect in the older lambs. The worm populations consisted mainly of early fourth stage larvae and developing worms, but a small percentage reached sexual maturity and these produced a low faecal egg count (1 to 63 eggs per gram). Numerous intraluminal refractive crystals were present in the gut of both adult worms and developing stages, possibly reflecting degenerative changes. Hypertrophy of the abomasal mucosa with patchy loss of differentiation was a feature of the infection, and in four lambs serum pepsinogen concentrations were elevated. Exposure to O ostertagi did confer some protection against challenge with O circumcincta in that worm counts were reduced to about 60 per cent of those in controls, although no increase was observed in the numbers of arrested larvae. The successful passage of O ostertagi through young lambs could be important in mixed or alternate grazing systems by providing a reservoir of infection for the alternate host.     

Observations on the egg output resulting from continuous low level infections with Ostertagia circumcincta in lambs

Faecal egg counts were determined twice weekly for two groups of four-month-old worm free cross Suffolk lambs experimentally infected with 100 and 320 Ostertagia circumcincta larvae, five times per week for 20 weeks. The group mean egg count in both groups rose to a maximum of approximately 500 eggs per gram during weeks 12 to 14 and had fallen to less than half of that value at slaughter. There was no statistical difference in egg output between these two groups or between them and a comparable group of lambs receiving 4000 Ostertagia circumcincta larvae per day. No significant changes in live weight gain or serum pepsinogen levels were observed in the lambs given 100 and 320 larvae per day.     

Efficacy of abamectin against natural infections of gastrointestinal nematodes and lungworm of cattle with special emphasis on inhibited, early fourth stage larvae of Ostertagia ostertagi.

The anthelmintic efficacy of abamectin (avermectin B1) was evaluated against gastrointestinal nematodes, including Ostertagia ostertagi inhibited larvae and lungworm, in yearling crossbred beef heifers during late spring. The calves were grazed on contaminated pasture for 10 weeks and then held under conditions free of nematode infection for 3 weeks prior to allotment and treatment on 5 June. Thirteen calves were randomly assigned to two groups of six by restricted randomization on body weights; the extra lightest calf was assigned to the non-treated control group. Group 1 calves were treated with abamectin at 200 micrograms kg-1 body weight by s.c. injection and Group 2 calves were not treated; all were killed at 14 days after treatment. Ostertagia ostertagi was present in all controls; arithmetic mean numbers of adults, developing fourth stage larvae (L4) and inhibited EL4 were 7683, 605 and 36,102, respectively. Other nematode genera present in controls in sufficient numbers for the experiment were Haemonchus placei adults, Trichostrongylus axei adults, Cooperia spp. adults, Oesophagostomum radiatum adults, Bunostomum phlebotomum adults, Dictyocaulus viviparus adults and E5 (immature adults). Abamectin was highly effective (consistently greater than 99% efficacy and P less than 0.05) in removing all nematodes present in treated calves as represented in non-treated controls, including the primary target of Ostertagia ostertagi inhibited EL4. The lowest efficacy was 93.8%, against D. viviparus E5.     

Nematode parasitism in adult dairy cows in Belgium

Over a period of 1 year, from November 1997 to October 1998, the abomasa, blood and faecal samples of 121 dairy cows in Belgium were collected and examined for nematode infections. Nematodes were present in the abomasa of 110 animals. Ostertagia was found in all 110, Trichostrongylus was seen in 65 and Haemonchus in 14 abomasa. Overall, 91% of all trichostrongyles recovered were Ostertagia. The geometric mean total number of Ostertagia was 2750, with an average of 74% inhibited early fourth stage larvae (EL4). Between November and February >90% of the Ostertagia worm burden were EL4 stages. The majority of the animals (56%) harboured a low Ostertagia burden (100-5000) and 15% had a high burden (>10,000). Sixty-four percent of the coprocultures were positive and the genera recovered were Ostertagia sp. (100%), Trichostrongylus sp. (42%), Oesophagostomum (32%), Haemonchus sp. (29%) and Cooperia sp. (16%). A seasonal pattern was evident for serum Ostertagia-specific antibodies and for serum pepsinogen concentration, with the highest levels during the summer, and low values during the winter. Dictyocaulus viviparus specific antibodies were detected in the serum of eight (7%) animals.     

Forms of bovine pepsinogen in plasma from cattle with three different 'syndromes' of Ostertagia ostertagi infection

Calves infected orally with third stage larvae of Ostertagia ostertagi or infected with adult O ostertagi by direct transplantation into the abomasum had raised plasma pepsinogen activity, as did four-year-old dairy cattle challenged with O ostertagi third stage larvae on five occasions. Using fast protein liquid chromatography two forms of pepsinogen; pepsinogen 1 (PG1) and pepsinogen 2 (PG2) were identified in each of the parasitic infection regimes.     

Attempts to produce protection against Ostertagia ostertagi in cattle.

Various single or multiple doses of Ostertagia ostertagi were administered to young calves, and the production of protection phenomena elicited by single challenge inoculations ranging from 50,000 to 300,000 larvae or multiple challenge inoculations totaling 98,000 and 300,000 larvae was investigated. With some regimens, the vaccinations apparently resulted in protection against challenge exposure, as reflected by 36 to 56% fewer worms becoming established in challenge-exposed vaccinated calves than in challenge-exposed nonvaccinated, control calves. Other protection phenomena were elicited by some vaccinated calves of significantly more female worms lacking the distinctive vulval flap of O ostertagi and harboring significantly fewer eggs per female. Challenge exposure with a pathogenetic dose of 300,000 larvae produced the same degree of retarded weight gain in vaccinated as in nonvaccinated calves, and at necropsy, visceral lesions and pathologic alterations were equally severe in both groups of calves.     

Ostertagia ostertagi challenge of calves vaccinated with Haemonchus placei intestinal homogenate

The protective capacity of vaccination with Haemonchus placei whole gut homogenate against challenge with the non-blood-feeding nematode Ostertagia ostertagi was evaluated in calves. Ten helminth-free calves were randomly assigned to two groups. Group 1 received 100microg H. placei intestinal homogenate in the adjuvant 5% dextran sulfate/PBS, while Group 2 received the adjuvant alone. Injections were administered subcutaneously on Days 0 and 28. All calves were challenged with approximately 26,100 O. ostertagi larvae on Day 42. Serum antibody response and counts of nematode eggs per gram of feces (EPG) were determined throughout the study. Calves were necropsied at 5.5 weeks post-challenge for recovery of nematodes. Although significant increases were detected in both serum IgG(1) and IgG(2) of Group 1 calves (p<0.05), there was no significant difference in the total number of O. ostertagi recovered from the two groups (p>0.05). Lengths of adult nematodes were not significantly different between groups nor were the numbers of eggs present in adult females recovered from each group significantly different (p>0.05). There were also no significant differences between groups regarding fecal egg counts (p>0.05). Results suggest either: (1) the antigens targeted by the induced antibodies were not present in O. ostertagi; (2) the antigens targeted by the induced antibodies were present, but not essential to O. ostertagi survival; or (3) the antigen was present and essential, but amount of antibody ingested was insufficient to cause damage to the nematode.     

The efficiency of levamisole, thiabendazole and fenbendazole against naturally acquired infections of Ostertagia ostertagi in cattle

In two experiments, conducted in cattle with naturally acquired infections of Ostertagia ostertagi, comparative assessments were made of the anthelmintic efficiency of levamisole, thiabendazole and fenbendazole, each at 1.0, 1.5 and 2.0 times the recommended dose rate. Variable efficiencies of 81 and 49 per cent for levamisole, 86 and 56 per cent for thiabendazole were obtained against adult O ostertagi. Neither drug showed substantial activity against early fourth stage larvae. Efficiency of fenbendazole against adult O ostertagi was consistently high; 85 and 89 per cent in the two experiments respectively. In the first experiment in which cattle were slaughtered two to three days after treatment, only 22 per cent of inhibited early fourth stage larvae were removed whereas in the second experiment when slaughter took place 10--11 days after treatment, this efficiency was 89 per cent. There was no increased effect of increased dose rates on treatments with thiabendazole or fenbendazole. The activity of levamisole against adult worms and inhibited larvae was increased at twice the recommended dose rate.     

Nematode parasites of adult dairy cattle in the Netherlands

Abomasa, blood samples and faecal samples for examination of nematode infections were collected from 125 dairy cows during the period November 1997-October 1998. Of these, 12 had no grazing history and were, therefore, excluded from this study. From the remaining 113, 88.5% had nematode eggs in the faeces. Larval identification of the positive cultures showed that Ostertagia spp. larvae were most frequent (97%), followed by Trichostrongylus spp. (29%), Oesophagostomum spp. (23%), Cooperia punctata (20%), Cooperia oncophora (4%), Haemonchus contortus (2%) and Bunostomum phlebotomum (1%). The geometric mean EPG was 2.4. Two cows excreted larvae of Dictyocaulus viviparus (0.1 and 0.6 LPG resp.). Worms were found in the abomasa of 108 cows (96%). In all these abomasa Ostertagia spp. was present (100%). Trichostrongylus axei was found in 47 abomasa (43.5%) and two cows (2%) were infected with Capillaria bovis. The geometric mean of the total abomasal worm counts was 1743 and of Ostertagia spp. alone 1615. Almost all male worms were Ostertagia ostertagi, only occasionally Skrjabinagia lyrata10,000) total worm burden.Ostertagia specific antibodies were highest in late summer and autumn and lowest in spring and early summer. The same pattern, although not so pronounced, was observed for the serum pepsinogen values. No clear seasonal pattern was found for the Cooperia specific antibodies. Antibodies against D. viviparus were detected in seven cows (6%).     

Efficacy of levamisole against Ostertagia ostertagi in Louisiana cattle during maturation of inhibited larvae (September) and during minimal inhibition (December/January).

Levamisole (LEV) was tested in four experiments to compare efficacy values against Ostertagia ostertagi when larval maturation was occurring (September), following inhibition and also when populations were expected to be largely adult (winter). A primary objective was to determine the importance of developing fourth-stage larvae (DL4) and inhibited, early fourth-stage larvae (EL4) in replacing adult worms lost through treatment and the effect of this on reduced efficacy against adult worms. Young crossbred beef calves ranging in weight from 150 to 230 kg were used in the first (September 1981), second (September 1983) and third experiments (January 1987). Jersey calves of 110 kg average weight were used in the fourth experiment (December 1988). Calves were randomized to groups according to weight and group sizes ranged from three to five calves. All parasite infections were naturally acquired, but a mixture of nematode third-stage larvae (L3) (22,500 per calf), including 20% Ostertagia ostertagi, was inoculated into Jersey calves of Experiment 4 following a 2 week exposure to natural infection. All LEV treatments were by subcutaneous injection at dosages of 6 and 8 mg kg-1. Treatment with ivermectin was used only in Experiment 3 as an efficacy reference. All calves were killed at 8-10 days after treatment. The efficacy of LEV against all developmental stages of Ostertagia ostertagi was consistently low in all experiments and a dose-dependent response was not evident. Large numbers of all Ostertagia ostertagi developmental stages were present in non-treated calves in both September experiments. Percent reduction of adults, DL4 and EL4 at the 6 mg kg-1 and 8 mg kg-1 dosages, respectively, were adults, 51.7 and 23.6 (1981), 8.7 and 51.3 (1983); DL4 40.3 and 13.2 (1981), 37.9 and 33.1 (1983); EL4, 19.6 and 0 (1981), 59.6 and 42.9 (1983). Smaller numbers of Ostertagia ostertagi were present in winter experiments and adult worms greatly outnumbered larval stages. Percent reductions of adults, DL4 and EL4, respectively, were (1987) LEV 6 mg kg-1, 40.2, 0 and 0; ivermectin 200 micrograms kg-1, 98.7, 97.7 and 100.0; (1988) LEV 6 mg kg-1, 62.4, 100.0 and 100.0; LEV 8 mg kg-1, 49.1 65.0 and 74.1. Too few larval stages were present in the latter experiment for valid efficacy values.(ABSTRACT TRUNCATED AT 400 WORDS)     

Suspected resistance of Ostertagia ostertagi in cattle to levamisole

Observations on a beef cattle farm in Flanders led to the suspicion of resistance to levamisole in a strain of Ostertagia ostertagi. After treating a group of six animals with levamisole (5 mg kg-1 L.W., i.m.) the reduction in the number of trichostrongylid eggs per gram of faeces varied between 0 and 66.6%, whereas a similar group treated with fenbendazole (7.5 mg kg-1 L.W., p.o.) showed a reduction in worm burdens of 100%. Coproculture showed that the remaining eggs in the first treatment group were all Ostertagia sp. The suspected field strain was compared with a reference strain of O. ostertagi by means of the in vitro larval paralysis test. This test showed LC95 values of 9.12 micrograms ml-1 and of 99.04 micrograms ml-1 for the reference and the field strain respectively, which indicates a resistance factor for the latter of 10.9. These results were not unequivocally confirmed by the post mortem findings on a tracer calf necropsied 4 days after treatment with levamisole.     

Interpretation of abomasal worm burdens in cattle

The significance of the worm burden in the diagnosis of parasitic gastroenteritis is examined. It is emphasised that the worm population is in a dynamic state with the calf constantly losing part of its worm burden while picking up new infective larvae. The numbers and proportion of late fourth stage Ostertagia ostertagi larvae gives an indication of the success of the animal in controlling its worm burden. During an examination of the worm population it is also necessary to look at the condition and degree of development of adult female worms to assess the efficiency of the calf's acquired resistance to infection.     

Seasonal prevalence of gastrointestinal nematodes of beef calves grazed on irrigated pastures in the lower Sacramento Valley of California

Two worm-free calves were allowed to graze on irrigated pasture with a naturally infected herd for each of 34 one-month periods from November 1979 to August 1982. After each grazing period, the calves were transferred to a cement-floored pen for 3 weeks and then were euthanatized and necropsied. Ostertagia ostertagi and Cooperia oncophora were the most prevalent species of nematodes recovered. Adults and larvae of Ostertagia spp and Cooperia spp were most numerous in winter and spring and least numerous during summer. The proportions of Ostertagia spp that were inhibited as fourth-stage larvae increased in late fall, peaked from March through April, and then decreased to low values during summer. The maximal inhibition in 1980, 1981, and 1982 was 72, 65, and 62%, respectively. The number of larval Cooperia spp was highest in winter months and, except for one grazing period when 55% of the Cooperia spp were larvae, the total numbers represented less than 15% of the nematode population during all grazing periods. Other nematodes encountered were Trichostrongylus axei, Haemonchus spp, O lyrata, and O occidentalis in the abomasum; C surnabata, C punctata, Nematodirus helvetianus, T colubriformis, and Bunostomum phlebotomum in the small intestine; and Oesophagostomum venulosum and Trichuris ovis in the large intestine.     

Efficacy of ivermectin delivered from a sustained-release bolus against inhibited early fourth-stage larvae of Ostertagia ostertagi and other nematodes in cattle.

The anthelmintic efficacy of ivermectin (IVM) delivered from a sustained-release (SR) bolus was evaluated against natural infections with gastrointestinal tract nematodes in 12 crossbred beef heifers in spring. The 12 calves were randomly allotted to 2 groups of 6 calves each. Group-1 calves were treated with an SR bolus designed to deliver 8 mg of ivermectin/d. Group-2 calves were nontreated controls. Cattle groups were kept in separate concrete-floored pens (grass hay nutrition) and slaughter was performed at 35 days after treatment. Fecal egg counts for group-1 calves remained zero after treatment, except for detection of less than 1 egg/g of feces in 1 calf at the time of slaughter; counts in nontreated calves increased. Mean and range of Ostertagia ostertagi inhibited larvae in nontreated calves were 27,093 and 10,622 to 56,368, respectively. Efficacy of the IVM SR bolus was 100% against O ostertagi developing fourth-stage larvae (L4) and inhibited early L4, Haemonchus placei adults, Cooperia punctata and C spatulata adult males, Cooperia spp adult females, Cooperia spp L4, Trichostrongylus colubriformis adults, Bunostomum phlebotomum adults, and Oesophagostomum radiatum adults. Efficacy for O ostertagi and T axei adults was 99.9%. Numbers of nontreated calves infected with C pectinata adult males and Oes radiatum L4 were too low to evaluate efficacy. Calves treated with the IVM bolus gained 10.2 kg, whereas nontreated calves lost 1.8 kg. Abomasal lesions were clearly greater in nontreated calves on the basis of index comparisons of abomasal weight and total live weight and gross pathologic features.