Repeated freezing of bull semen (author's transl)]

Repeated freeze-thaw cycles have been used as a mean to predict the viability and fertility of bull semen. In order to investigate the level of fertility of bull semen that has been frozen, thawed and refrozen again, two split sample field trials were performed. 25 bulls were used in the trial, and inseminations were performed by 30 technicians. The semen was diluted to 27 million spermatozoas per dose in a skimmilk-fructose extender, and filled in the french mini-straw. The straws were coded by use of a batch number system. The one half of the straws was fixed to the freezing rampes. After freezing and transfering of the rampes to liquid nitrogen, the rampes were placed in a water-bath at + 35 degree C in 7 seconds. Immediately after thawing the straws they were transferred to a refrigidaire room at + 5 degree C, dried, remounted on the rampes and frozen again in the ordinary way. The other half of the straws were frozen according to the normal routine. The semen from the two treatments were distributed in equal numbers to the technicians who were not informed of the trial. The motility after refreezing had decreased and the percentage of intravital eosin spermatozoas after refreezing increased by 23, as an average. Fertility results were estimated as 60 days non returns after 1st inseminations. Single frozen semen: 1488 1st ins. 493 ret. 66,86 N.r.-% Refrozen semen: 1511 1st ins. 500 ret. 65,30 N.R.-% The trials indicate that further investigation should be performed to see if semen might be frozen concentrated, rediluted after thawing and refrozen for distribution to the technicians.     

Intrauterine insemination in ewes with frozen semen (author's transl)]

110 ewes were allocated for intrauterine insemination. One succeeded to deposite semen intra uterine in 43 of the ewes and 37 (86%) of these lambed. In the remaining 67 the semen was deposited in cervix, and of these 15 lambed (22,4%). Totally 52 (47,3%) of the inseminated ewes lambed. Similar results were obtained by one or two inseminations in the heat. Dilution 1:3 gave a significantly (p less than 0.05) higher lambing rate than dilution 1:9 when the semen was deposited in the cervix, while the results were similar for dilution 1:3 and 1:9 by intra interine deposition. A group of 49 ewes was inseminated according to the conventional method on the first day of heat and the intra uterine method on the second day. Intra uterine deposition of semen succeeded in 31 ewes and 27 (87,1%) lambed. In the 18 remaining ewes the semen was depposited in the cervix and 9 (50%) lambed. Totally 73,5% of the ewes in this group lambed.     

Fertility and fertility problems in some beef herds in Sweden (author's transl)]

The purpose of the study was to investigate the fertility level, some factors affecting fertility and problems of infertility in selected Swedish beef herds. The investigation included 31 herds, 19 of which had Herefords, 13 Charolais, 2 Aberdeen Angus and 1 Limousins. The total number of mature females was 703, including 147 feifers of breeding age. Most data were collected at personal visits to the herds. The results are presented in Tables I--XV and Figures 1--2. The service period coincided roughly with the grazing period and lasted usually 4--5 months. Seventyfive per cent of the females calved during the period February-May. The fertility levels were comparatively good. The percentage of pregnancy at rectal examination performed at the end of the service period was 89.5; however the average calving percentage was only 87.5. The highest calving percentages were recorded for Aberdeen Angus and crossbreds. Also the calf crop, it is the number of calves born alive and surviving 24 hours per mature female was the highest for these two groups; 0.91 and 0.90 respectively. The mean interval from calving to conception was 80.3 days in Herefords, 83.4 days in Aberdeen Angus, 85.6 days in crossbreds and 92.3 days in Charolais. The percentage of animals pregnant within 90 days after calving was on an average slightly more than 50 per cent. The interval from calving to conception rose gradually when the interval from calving to expoure to bull exceeded 40 days. Mean percentages of still born calves were 5.9 in cows and 13.7 in heifers. As far as the fertility level is concerned there does not seem to be any disadvantage in keeping the bull together with the females during the calving period. However, in this case the next calvings will occur over an extended period of time. If the intention is to concentrate 50 per cent of the calvings within the period of one month then the females should be exposed to the bull from 41--60 days after calving at the earliest. In case the females were exposed to the bull from 41--60 days after calving and onwards, 95 per cent of the females finally pregnant had conceived at the end of a 3 months service period. Under such conditions a bull may be able to serve two groups of females within the same grazing period. Cows calving during July-September had the lowest pregnancy rate and those calving during October-December the highest at the following service period. The incidence of ovarian cysts was very low. About 1/3 of those buls serving at least 10 females each obtained calving percentages less than or equal to 80. Herds recording low calving percentages had to a great extent used young bulls, 12--15 months of age at the beginning of the service period. Only for two groups of females out of eleven which had been served by young bulls calving percentages greater than 80 were noted. A more efficient control of the fertility of the bulls could markedly improve the fertility of some herds.     

Parathion poisoning in cattle (author's transl)]

In a herd of dairy cattle half of the cows showed symptoms of acute poisoning. Blood- and hair samples were taken from seven of the cows, of which two did not show any clinical symptoms. The cholinesterase activities were in all the blood samples decreased to about 10 per cent of normal and parathion was found in all hair samples. The cholinesterase activities rose gradually during a 31/2 month period to the lower part of the normal range. Parathion was found in samples from the inner walls of the cowstable, and it was concluded that the poisoning was probably due to parathion spraying in the stable, while a suspicion of winddrift as a source of poisoning was rejected as less probable.     

Actinobacillus infections in swine (author's transl)]

Actinobacilli infections in pigs are relatively rare. Most cases were septicaemic in the first week of life. With increasing age manifestations after generalized infections were characteristic, such as arthritis, polyarthritis, endocarditis, nephritis, osteomyelitis and embolic pneumonia. Of 34 porcine strains 33 were identified as A. equuli and only one was identical with A. suis. The justification of retaining this species is discussed.     

Pesticide residues in feed-stuffs in Sweden (author's transl)]

The occurrence of pesticide residues was studied in samples of feed-stuffs produced in Sweden or imported to Sweden during the years 1972--1976. In all, 278 samples representing 37 types of feed-stuffs (components, as well as finished feeds) and 18 countries were analyzed. Residues of chlorinated hydrocarbon pesticides and PCBs were looked for in 224 samples, mostly feed components. The analytical method used involved solvent extraction, florisil-column clean-up, thinlayer chromatographic separation and gas-chromatographic determination. Chlorinated hydrocarbons were found in several samples. DDT and its transformation products were detected in 66 samples (29.5%), lindane in 44 (19.5%), PCBs in 25 (11.2%), alpha-BHC in 22 (9.8%), beta-BHC in 11 (4.9%) and dieldrin in 9 (4.0%). The levels were usually low (Table I). The chloropesticides occurred most frequently and at the highest levels in feed-stuffs of animal origin and in imported oil-feeds. In 25 of the samples the contents of sigmaDDT exceeded the maximum limit accepted by the National (Swedish) Food Administration for grain and bran intended for human consumption (0.05 mg/kg, Talbe IV). The highest residue level of sigmaDDT (0.66 mg/kg) was encountered in a sample of fish meal. The PCB levels found did not exceed the temporary tolerance established by FDA (1973) for finished animal feeds (0.2 mg/kg). One hundred and seven samples were analyzed for phenoxy acid residues using a thin-layer chromatographic and gas-chromatographic technique. Phenoxy acids were detected in only 2 of 62 randomly selected feed samples (0.05 and 0.2 mg/kg, respectively). The residue limit established by the National Food Administration for 2,4-D and MCPA in grain and bran intended for human consumption is 0.1 mg/kg. Fortyfour samples of feeds were submitted because of suspected phenoxy acid contamination. In 12 of the samples phenoxy acid residues were found. The highest level (3.5 mg/kg, MCPA) was observed in a sample of accidentally contaminated molasses. Considering the apparently low level of contamination of Swedish grain with chloropesticides, PCBs and phenoxy acids and the dilution on compounding feed-stuffs of animal origin and oil-feeds, only very low pesticide residue levels can be expected in Swedish finished animal feeds.