Effect of sex and exogenous porcine somatotropin on longissimus muscle fiber characteristics of growing pigs

Thirty-seven pigs with an initial live weight of 60 kg were used to investigate the effects of daily exogenous porcine somatotropin (pST) administration at two dose levels (0 and 100 micrograms.kg-1.d-1) for a 31-d period on muscle fiber characteristics and meat tenderness of boars, gilts and barrows. Excipient boars and gilts had more alpha W and fewer alpha R fibers than did those receiving pST. The percentage of muscle fiber type for barrows was not affected by pST treatment. The administration of pST resulted in an increase in muscle fiber size for all three fiber types in all three sexes, but these changes were of greater magnitude in barrows (31.8%) and gilts (27.8%) than in boars (9.3%). Somatotropin negated the intrinsic sex effect differences in fiber area of the pigs. There was no difference in tenderness among excipient boars, barrows and gilts; however, with the inclusion of pST, shear force decreased in boars and gilts and increased in barrows. A high proportion of the pST-treated pigs contained giant fibers in the longissimus muscle. Furthermore, a small proportion of the pST-treated pigs exhibited pale, soft, exudative muscle. Whether the giant fiber anomalies occurred through increased muscle activity or from fibers undergoing degenerative changes was not determined.     

A comparison of two laboratory methods of maintaining field-collected Lymnaea tomentosa for the production of Fasciola hepatica metacercariae

Four replicates of 50 field-collected Lymnaea tomentosa were maintained in two laboratory culture systems and their efficiency and practicability for the production of Fasciola hepatica metacercariae were assessed. There was no significant difference in the total number of metacercariae produced (56 552 from 64 snails in the closed container system and 54 073 from 82 snails in the shallow aquarium system).There was no significant difference between culture systems as assessed by snail survival, the number of infected snails or the number of infected snails harvested for the recovery of metacercariae. Within both systems there was a significant effect of snail size on the number of metacercariae produced. Optimum survival and production of metacercariae was achieved in young adult snails of 5–8 mm shell length at the time of infection.The collection of L. tomentosa from the field habitat and their maintenance in either culture system was shown to be a practical alternative to the breeding of laboratory adapted strains of L. tomentosa for the regular production of large numbers of F. hepatica metacercariae.     

Interferon inducers and foot-and-mouth disease vaccines: influence of two synthetic polynucleotides on antibody response and immunity in guinea pigs and swine.

Polyriboadenylic-polybouridylic acid enhanced the immunological response of guinea pigs to aqueous foot-and-mouth disease virus vaccine. Polyriboninosinic-polyribocytidylic acid enhanced the early antibody production of swine to oil emulsified foot-and-mouth disease virus vaccine. Polyriboninosinic-polyribocytidylic acid alone did not stimulate resistance to foot-and-mouth disease in swine.     

Adrenocortical involution in rats during oestrus synchronisation with medroxyprogesterone

Daily treatment of female rats with medroxyprogesterone acetate in aqueous suspension resulted in adrenocortical atrophy. The doses given were those used for oestrus synchronisation. Intramuscular injections of 2-0 mg medroxyprogesterone acetate were used to investigate the atrophic process. Adrenocortical involution was associated with extensive single cell deletion (apoptosis). It is suggested that theses changes were due to suppression of pituitary ACTH secretion. The cytological changes support the concept that single cell death plays an important role in organ remodelling. Biochemical determinations of DNA, RNA, protein and dry matter, and histological examination, did not reveal significant changes in the liver.     

Interaction of dietary protein content and exogenous porcine growth hormone administration on protein and lipid accretion rates in growing pigs

Sixty-six intact male pigs were used to investigate the relationships between exogenous porcine growth (pGH) administration (0, excipient-treated, and .09 mg recombinant pGH.kg-1.d-1) and dietary protein content (8.3, 11.4, 14.5, 17.6, 20.7 and 23.8%) on protein and lipid accretion rates over the live weight range of 30 to 60 kg. Feed intakes were restricted (1.84 kg.pig-1.d-1) and pGH was administered daily by i.m. injection. Rate of protein deposition increased with increasing dietary protein up to 17.6 and 20.7%, respectively, for control and pGH-treated pigs; both growth and protein deposition were enhanced by pGH on the four higher protein diets but remained unaffected by pGH administration to pigs given the two lowest protein diets. Plasma IGF-I concentration was elevated by pGH administration in pigs given the four higher protein diets but unaffected by pGH with the two lowest protein diets. Rate of fat deposition was depressed on all dietary protein treatments by pGH administration; carcass fat content of control and pGH-treated pigs declined with each increase in dietary protein up to 17.6 and 23.8%, respectively. The results demonstrate that pGH acts independently on protein and lipid metabolism.     

The impact of changes in sewage treatment on seaducks wintering in the Firth of Forth,Scotland

Changes in the numbers and distribution of seaducks wintering in the Firth of Forth off Edinburgh following the introduction of sewage treatment are described. Numbers of scaup and goldeneye were considerably reduced and feeding flocks were only recorded at outfalls where sewage continued to be discharged in large quantities.Although food items borne in the sewage were important in determining local distribution patterns, it was unclear whether these or abundant invertebrates were the most important factor attracting seaducks to this area.As a result of an environmentally desirable improvement scheme the United Kingdom has lost an internationally important concentration of wildfowl.     

The effect of Taenia hydatigena infection on existing and concurrent infections of Fasciola hepatica in sheep

Sheep given a primary infection of Fasciola hepatica were challenged 18 weeks later with Taenia hydatigena or F hepatica, or both parasites together, or were not challenged. At the same time, control sheep were infected with T hydatigena and/or F hepatica separately or concurrently. All sheep were killed seven weeks after challenge and the number of cysts and flukes counted. Challenge infection with T hydatigena did not affect the numbers of flukes recovered from either primary or challenge F hepatica infections. On the other hand, the numbers of cysticerci were reduced in sheep previously infected with F hepatica but not in those given T hydatigena and F hepatica concurrently.     

A farming systems study of abortion in dairy cattle on the Atherton Tableland: 2. The pattern of infectious diseases

The role of infectious agents on dairy farms on the Atherton Tableland in tropical north Queensland was studied as part of a comprehensive investigation into the causes of bovine abortion. The prevalence of antibody in serums collected from 7 herds whose annual abortion rates ranged from 3% to 21% were as follows: Leptospira hardjo 49.9% (426/853), L. pomona 0.4% (3/851), bovine virus diarrhoea (BVD) 33.7% (35/104). Infectious bovine rhinotracheitis virus (IBR) 11.5% (12/105), Akabane virus 92.2% (95/103), Aino virus 62.1% (64/103), Chlamydia psittaci 3.1% (37/1004), Brucella abortus 0% (0/851), and Toxoplasma gondii 0% (0/105). Testing of serums against a wide range of leptospiral serotypes indicated that reactions occurring in the Hebdomadis and Sejroe serogroups were probably cross reactions with L. hardjo. Infection with L. hardjo and Akabane virus occurred prior to first mating and contact with Aino virus occurred during first pregnancy. Infection with BVD and IBR viruses was sporadic. The pathology and microbiology of 32 aborted foetuses from 24 Tableland herds (10 from the group of 19 farms under more intense study) were performed. Lesions associated with a Sarcocystis-like agent were present in 6, leptospires in 1, suspected toxic hepatosis in 2 and purulent bronchopneumonia (Staphylococcus aureus) in 1 foetus. No diagnoses were made in the remaining 22 foetuses (69%). Evidence for a common infectious cause of abortion in the population was inconclusive.