Initial and developed free fatty acid concentrations in milk from paired normal and septic subclinically mastitic udder quarters.

The free fatty acid (FFA) content of milk from the paired normal (N) and septic (Staphylococcus aureus or S. agalactiae) subclinically mastitic (SSM) quarters of dairy cows was determined by thin layer chromatography. Within-cow comparisons showed the FFA content of milk from the SSM quarters to be consistently significantly higher than that of the opposing N quarters: initially and after warm agitation and both rapid and slow cooling prior to storage at 4 degrees C for 48 h. No correlation existed between initial and post-treatment FFA levels in milk from N quarters, but a significant positive correlation in the case of SSM milks suggests their greater susceptibility to both spontaneous and induced lipolysis. There was no correlation between the somatic cell content and FFA levels of either freshly-drawn or processed SSM milk. The study emphasises the importance of healthy udders in the production of milk of acceptable flavour and aroma.

[Collagen in boerewors as a measure of quality]. / Kollageen in boerewors as maatstaf van gehalte.

Formalin-fixed samples (n = 75) of commercial boerewors (traditional farm style sausage) were examined for total nitrogen (N) and hydroxyproline (Hypro) N to assess their collagen content. Hypo N/total N x 10(3) (unaffected by residual fat) varied from 8.23 to 16.50; 3/75 (5%) of samples had ratios equal to or less than the control (8.38) i.e. sausage home-made from meat without addition of scraps or collagen-rich trimmings. About 95% of samples had ratios greater than 10, and 5% had ratios greater than double the control. In 75% of the surveyed samples, the ratios were more than 1.5 times greater than those of the control. To ensure boerewors of good compositional quality, it is advocated that formalin-fixed samples of the product be subjected to both histological examination and collagen determinations. Promulgation of legislation to limit the collagen content of boerewors is proposed; a maximum of 12 in the ratio of Hypro N/total N x 10(3) is considered reasonable and attainable in the light of the results of this survey.

Blood biochemical parameters and meat pH of feedlot cattle slaughtered on arrival or after overnight rest at an abattoir.

The effect of different pre-slaughter rest periods at the abattoir before slaughter on the blood biochemical parameters and meat pH of a number of cattle were studied on 2 occasions, once in summer and once in winter. In the first trial, 42 out of a consignment of 50 and in the second trial, 45 out of a consignment of 54 feedlot-finished oxen were randomly selected and divided into 3 groups each. One group was slaughtered on arrival at the abattoir, a second group 3 h after arrival and the third group was rested in the lairage prior to slaughter the following day. Carcasses were subjected to low voltage electrical stimulation at slaughter. Significant differences between the values obtained at the feedlot and those at the abattoir were found in respect of haematocrit, total plasma protein concentration, plasma glucose, plasma creatine kinase, plasma lipid and cortisol concentration in both the trials. In general, however, no great differences were found between the 3 groups in either of the trials. If any, results in respect of some of the blood parameters were in favour of the groups slaughtered as soon as possible after arrival at the abattoir. No significant differences were found in the initial (35-45 min) and ultimate (24 h) pH of the meat between the 6 groups of slaughtered animals in the 2 trials. Exsanguination appeared to be satisfactory in all groups and no differences between groups were found. It was concluded that feedlot cattle transported to an abattoir over a relatively short distance, need not necessarily be rested in the lairage overnight before slaughter.

On the inactivation of Brucella abortus in naturally contaminated milk by commercial pasteurisation procedures.

Following concern about the recent publication indicating the possible ability of Brucella abortus to survive commercial pasteurisation of naturally contaminated milk, such milk was subjected to biological (BT), serological and bacteriological tests. The raw milk was Brucella Milk Ring Test positive and biotype I was isolated from 4/5 BT guinea pigs, the one tested being seropositive to the Rose Bengal Test, and with serum agglutination and complement fixation titres of 160 and 36 international units respectively. After batch (63 degrees C/30 min) and high temperature, short time (72 degrees C/15 sec) pasteurisation, all 10 BT guinea pigs were bacteriologically and serologically negative, indicating that officially approved methods of commercial pasteurisation rendered naturally Brucella-contaminated raw milk safe for consumption.

Levels of glucose, serum albumin and somatic cells before and during early stages of acute clinical mastitis artificially induced in cows by means of human strains of group-B streptococci (GBS) administered intracisternally.

The investigation was performed on 3 cows, sampled repeatedly before and during the initial 48 h of artificially induced, acute, clinical mastitis. The results of the investigation both augment and support those of earlier work on the levels and significant correlations of glucose, serum albumin and somatic cells in normal and abnormal secretions monitored before and after the usual milking of healthy lactating cows had been suspended. During acute mastitis, udder secretions from artificially infected quarters showed highly significant escalations of somatic cell counts which coincided with equally significant increases of a high and intermediate level of serum albumin values in both the infected and non-infected quarters. Corresponding glucose values fluctuated from 0,07-0, 22 and 0,18-0, 32 mM in the former and latter quarters respectively. The selective and elevated transfer of serum albumin in otherwise unaffected quarters of acutely mastitic udders suggests rather specific collateral vascular and epithelial changes of unknown nature and magnitude. The data indicate that marked fluctuations of glucose may occur within and between quarters of individual and different cows respectively. Such variations could significantly affect phagocytosis and killing of bacteria challenging the intramammary leucocytic udder barrier before and particularly during manifestation of mastitis. Hence, udder health, although dependent on specific natural defence mechanisms such as the leucocytes and related systems in milk, may depend even more significantly on the supplies of glucose to and within the bovine mammary gland.

Experimental induction of bovine mastitis with human strains of group B streptococci (streptococcus agalactiae).

Intrapapillary deposition of 5-30 CFU of 6 separate human strains of Group B streptococci into 7 lactating quarters of 6 cows resulted in clinical mastitis in all. Identical streptococci were subsequently recovered from 6 of the affected quarters. Details of milk somatic cell counts, bacterial isolations and clinical findings are tabulated. The role of GBS in human medicine and the implications of proof that the bovine udder is susceptible to small numbers of GBS from human sources, are discussed.

Group B streptococcus-comparison of Streptococcus agalactiae isolated from humans and cows in the Republic of South Africa.

The serological and biochemical characteristics of 100 strains of Streptococcus agalactiae isolated from quarter mild of dairy cows and of 107 strains cultured from various sites of human patients, were determined and compared. All the isolates were CAMP-phenomenon and Na-hippurate positive, aesulin negative, fell into Lancefield's Group B and could be placed into one of the 6 recognised serotypes. No human isolates fell into type R but for the rest all the other types were represented in the series of bovine and human cultures. In order of frequency, the human isolates were of type III, II, Ib, X and Ia and the bovine of type II, X, III, Ia, Ib and R. Of the human and bovine cultures respectively, 34 and 96% altered litmus milk, 30 and 100% were sensitive to bacitracin, 32 and 4% were pathogenic to mice, 82 and 93% reduced the ultimate pH of glucose broth to 4,2-4,8, 36 and 100% fermented lactose, 93 and 99% salicin and 94 and 79% trehalose. Concerning the combination of lactose/salicin fermentation, 35 and 95% of bovine and human isolates were , 0 and 5% were , 59 and 0% were -/=nd 7 and 0% were -/-. Data are summarised in 5 tables and discussed against the background of reports from other countries. It appears that a proportion of the human infections concern organisms likely to have been derived from bovine sources, either directly or indirectly. Definite classification of South African GBS into either human or animal strains does not seem possible. It is concluded that it would be more correct to refer to the source of an isolate instead of inferring that because the organism was primarily cultured from, say human resources, it is necessarily a human "strain'.

The effect of sample size and culture method on the recovery of salmonella spp. from naturally contaminated carcase meal.

The results of parallel examination by two methods of 223 consignment samples of carcase meal were compared. Selective pre-enrichment of 5 g of sample prior to plating on to a solid media disclosed that 2,7% of consignments were contaminated with Salmonella. Non-selective pre-enrichment of 100 g followed by selective enrichment prior to plating food 21,5% of the consignment to contain Salmonella.

Subclinical septic bovine mastitis: critical evaluation of intramammary immunoglobulin therapy.

A series of 152 quarters affected with subclinical staphylococcal and streptococcal mastitis was treated at random by intramammary infusion with one of 4 formulations containing inert solvent, specially prepared immunoglobulin (Ig) and antibiotics (penicillin G and streptomycin) in various combinations. The effect of treatment was measured by assessing the conversion of mastitic quarters to a normal or mastitis-negative state over a post-treatment period of 28 days. Considering the solvent as a placebo, solvent plus Ig had no significantly better effect than solvent only; solvent plus antibiotics gave results that were highly significant after 14 days even though about a third of the strains of S. aureus were resistant in vitro to one or both of the antibiotics; solvent plus antibiotics and Ig gave results that were highly significant during the whole 4 weeks after treatment. The Ig solution appeared to be considerably more effective against staphylococcal than streptococcal mastitis, but the small numbers precluded statistical analyses. It was concluded that use of the particular batch of Ig alone had no value in the treatment of the common forms of subclinical bacterial mastitis but that in combination with antibiotics the Ig had a somewhat better effect than was obtained with antibiotics alone.

The comparative incidence of subclinical bacterial bovine mastitis in 17 herds when using two sets of diagnostic criteria.

On the single examination of 6804 quarter milk samples during a routine mastitis survey in 17 herds it was found that whereas 12,4% of quarters were diagnosed as subclinically mastitic when using the IDF standard set of diagnostic criteria, only 2,4% were positive when applying the additional criterium of a positive test for bovine serum albumin. The remaining 10% of quarters were then classified as being affected with septic inflammation of the ducts. The ratio of true subclinical septic mastitis to duct and test canal infections is recorded and the implications of the findings are briefly discussed.

The effect of gamma radiation on the cysticerci of Taenia solium.

Cysticerci of Taenia solium were exposed to gamma radiation in doses varying from 20-140 krad. Radiation had an adverse effect on the ability of the cysticerci to evaginate in vitro after a time lag of 9 days. This effect was most marked at doses of 100 krad and higher, thus no cysticerci exposed to 140, 120 and 100 krad evaginated after 12, 18 and 21 days, respectively. On Day +24, when 60% of the control cysticerci evaginated, 55%, 50%, 30% and 40% of the cysticerci exposed to 20, 40, 60, and 80 krad, respectively, evaginated in vitro. Cysticerci exposed to radiation doses of 20-120 krad are as infective to golden hamsters as are unirradiated cysticerci. Cestodes resulting from irradiated cysticerci, however, cannot maintain themselves indefinitely, and are excreted or digested at varying times from Day +12 onwards. Moreover, cestodes resulting from such irradiated cysticerci do not grow, but are resorbed, and finally consist of only a scolex. By Day +30 the mean length of the worms resulting from the unirradiated cysticerci is 173,8 mm, while those resulting from cysticerci exposed to 20 and 40 krad consist of scolices only and the hamsters fed material exposed to 60 krad were negative. It appears, therefore, that radiation inhibits the ability of the cells in the neck region to divide and thus form new proglottids. Carcasses infested with cysticercosis can possibly be rendered fit for human consumption by exposure to gamma radiation at doses between 20 and 60 krad.

Specific serological identification of ostrich meat and meat products.

Using aqueous urea solution extracts of heated ostrich muscle as antigen for the production of precipitating rabbit antiostrich sera, it was possible to specifically identify raw, heated (70-95 degrees C) and air dried-salted ostrich meat by means of gel immunodiffusion tests. The sera did not react with chicken, turkey or horse meat or with beef in any form. The soluble proteins extracted from ostrich meat heated to temperatures of 70 degrees C for 30 minutes appear to constitute at least two closely related antigenic determinants of which only one is thermostable at temperatures above 70 degrees C).