Udder Halves Research Articles

Cell Content in Goat’s Milk

The geometric mean cell count of goat’s milk in mid-lactation was 880 × 103 cells/ml and 690 × 103 cells/ ml estimated by the Direct Microscopic Count (DMC) and the Electronic Cell Count (ECC), respectively. The numerous cell fragments in goat milk may have had an influence on the results obtained by the cell counting methods compared. A highly significant correlation (P < 0.001) existed between the results obtained by the above mentioned methods, and the California Mastitis Test. If routine surveys are done on milk samples of goats, a CMT score of 1, 2 or 3 should be regarded as normal in the mid-lactation. A higher CMT score may indicate an abnormal condition of the udder. In the diagnosis of mastitis in goats great attention should be paid to the difference in cell content between milk samples from halves of the same udder.

Milk Iodine as Influenced by an lodophor Teat Dip1,2

We quantitated the increase of iodine in milk from iodophor teat dips and determined the mode by which that iodine entered the milk. In one trial with teat dipping for 1 wk, iodine in milk increased 8.8μg/100ml. In another trial, only right udder halves were dipped with the iodophor. Samples of milk from the left udder half increased in iodine corresponding to the right udder half only slightly less. Tincture of iodine was applied to the skin between the vulva and the point of udder attachment of cows. Samples of milk from the group with tincture increased markedly in iodine content over the control group. Iodophor teat dips increased the iodine in milk by 8 to 10μg/100ml. The primary mode of increased iodine appears to be absorption through the skin and entry into the milk by the milk synthesis process rather than by contamination from the teat's surface.

Effect of Prepartum Milk Removal on Quantitative Morphology of Bovine Lactogenesis

The effect of prepartum milking on bovine mammary histology and milk composition was studied in five Holstein cows. One udder half was milked twice daily starting 10 days before the estimated calving date. One udder half was not milked until 2 days postpartum when all quarters were milked and two tissue samples per quarter were taken for morphological analyses. Lactose, casein, and fat concentrations differed from prepartum-milked to postpartum-milked quarters (.82, −1.44, and 3.29%). Quarters milked prepartum were more developed: mature epithelium 24.8%, immature epithelium −8.9%, total epithelium 15.6%, stroma −24.8%, and alveolar lumen 8.5%. Most alveolar cells in prepartum-milked halves had prominent rounded basal nuclei, hypertrophied secretory vesicles, and a mixed array of lipid droplets. Cells within alveoli were morphologically similar. Secretory epithelial cells from postpartum-milked glands had irregular randomly located nuclei, indistinct Golgi, variable lipid content, and less cytoplasm. These differences demonstrate the importance of prepartum-product removal on secretory cell development and subsequent milk production.

Changes in Milk Products Sham Fed to Calves. IV. Suckling from a Nurse Cow versus Consuming from Either a Nipple Feeder or an Open Pail

Lipolysis and associated changes in whole milk sham fed by different systems to two pairs of calves (Guernseys and Holsteins, 2 to 5 mo of age) were compared. Each calf was sham fed milk from the respective halves of the udder of a Holstein cow by: (a) nursing directly from the udder, (b) sucking from a nipple pail, and (c) drinking from an open pail. Increasing rates of consumption by these methods were in the order listed. Exposures during ingestion increased lipolysis and numbers of bacteria. Lipolysis, evidenced by increased soluble volatile fatty acids and decreased concentrations of fat, was accompanied by lowered pH and by accelerated rates of rennet coagulation. Lipolytic changes were accentuated throughout an 8-h incubation at 38C. Magnitudes of lipolysis in milks removed by hand from the respective udder halves and subsequently sham fed by pail systems were related closely to the duration of ingestion. Hence, changes in milk sucked from nipple pails were more marked than in that drunk from open pails. Nursing from the udder was slower than by sucking from a pail, but lipolytic modifications were less, which difference is attributed to the lower fat content of nursed milk.

Error in Estimation of Contained Milk Volume in the Dairy Goat with Cerium-141

Cerium-141 as a nonabsorbable radiomarker was used in nine separate trials with two goats to determine milk volume by isotopic dilution techniques. A correction procedure, developed for guinea pigs, showed an average underestimate of contained milk volume of 1.1% (range, .61 to 4.06%) for goats having from 353 to 1,202ml of milk per udder half. A correction for incomplete penetration of cerium-141 into the alveolar spaces of the mammary gland is not needed in the goat.

Mammary Blood Flow and Glucose Uptake in Lactating Cows Given Dexamethasone

Dexamethasone (two 10-mg intramuscular injections 12h apart) was given to three lactating cows. Milk production decreased from 13.0±1.9 to 8.5±2.2 kg/day (mean±standard error). Mammary blood flow estimated by the antipyrine absorption method decreased in four of six half udders following dexamethasone. Changes in packed cell volume and plasma concentrations of free fatty acids, calcium, and magnesium and blood L-lactate were not significant. Mean blood 3-OH-butyrate concentration decreased from 6.4 to 4.5 mg/100ml. Plasma glucose concentration increased from 58±3 to 107±9 mg/100ml. Mammary arteriovenous differences of glucose were decreased by 41% and net mammary uptakes of glucose by 38%. Milk production was correlated with the mammary arteriovenous difference, extraction and net uptake of glucose, and the net uptake of glucose-plus-lactate but not with arterial glucose concentration. The results associate diminished milk production with diminished glucose uptake and utilization of glucose by the mammary gland rather than diminished availability of glucose in the blood.

Effects of Internal Irradation of the Mammary Gland with 144Cerium-144Praseodymium

Left udder halves of two Jersey cows were given intramammary infusions at six-week intervals with 144Ce-144Pr to give approximately 975, 650, and 1,300rad per treatment. Two other cows were given left-half treatments of 650 and 1,300rad 64 days apart. Milk yield of the treated halves remained comparable to that of the control halves until the last treatments, when it declined. Reduced hay consumption accompanied the decline in milk yields. Milk composition of treated and control halves did not differ significantly. One cow in a succeeding lactation showed a marked reduction of yield in the irradiated half. Nearly 15% of the radioactivity was retained in the body. High concentrations of 144Ce-144Pr accumulated in the liver, spleen, skeleton, and treated half mammary lymph glands. Histological evidence of damage to the mammary secretory epithelium was noted. Chronic hematopoietic damage occurred which resulted in death of three of the cows about four months after the last treatment. The fourth cow died two years later with extensive edema involving the left half of the udder. It was concluded that the mammary gland secretory epithelium is relatively resistant to irradiation damage, but is measurably affected at doses of 1,300rad. Effects on the mammary glands could not be completely separated from possible systemic effects of absorbed 144Ce.144pr

Effect of Gestation and Dry Period on Deoxyribonucleic Acid and Alveolar Characteristics of Bovine Mammary Glands

Udders of 21 lactating and 26 dry cows were analyzed for deoxyribonucleic acid (DNA) concentration and amount. Right and left halves of 21 cows were dried off at different times to give comparisons between dry periods of 15, 45, 60, and 75 days. Udders of five dry cows with dry periods of 8 and 48 days for right and left halves, respectively, were obtained about a week before calving. Histological sections of 26 udders were used to record alveolar density and surface area. The correlation coefiicient between total DNA and milk yield per half udder (r = 0.34) was small but statistically significant (P<.05). Concentration of DNA and alveoli increased in dry udders compared to prepartum and laxtating udders. Involution of udders of nonpregnant or early gestation cows was evidenced by reductions in fresh weight, dry weight, alveolar surface area, and DNA. In prepartum half udders, six weeks’ difference in dry period did not significantly affect dry weight, DNA, or alveolar concentration. Lack of interference with either involution or alveolar development in the udder due to short dry periods indicates that subsequent subnormal lactation may be due to subnormal function rather than structure.

THE IMMUNE RESPONSE OF THE MAMMARY GLAND AND REGIONAL LYMPH NODE FOLLOWING ANTIGENIC STIMULATION.

SummaryThe changes in the antibody and cellular content of milk and mammary lymph have been studied in ewes given intramammary infusions of various antigens. Killed Brucella abortus, Salmonella typhi and Salmonella pullorum, the antigens used in the experiments, were infused into one udder half while the other served as a control.Apart from a transient increase in the neutrophil content of the milk immediately following the infusion, there was no difference in the cell content of the milk of the infused or control glands throughout the experiments on lactating sheep. There was a relatively small increase in plasmablasts and plasma cells in the efferent lymph from the mammary gland following intrammary infusion compared with that following subcutaneous injection. There was at the most only a slight increase in antibody litre in the milk following infusion into mammary glands of lactating sheep and in all experiments the litre in plasma was higher than that in milk. On the other hand there was a substantial rise in antibody titre in the secretion from involuting glands. After two infusions at 10‐day intervals the litres in the secretion from the involuting gland and in the lymph draining it were many times higher than that in plasma. These results suggest that much of the antibody in involution milk was locally synthesized. Killed Salmonella typhix “O” organisms were infused into the glands of two pregnant ewes 2‐6 weeks before parturition. This resulted in high litres in the colostrum and in the milk for at least three months of the next lactation. The antibody titre of the milk from the infused side was higher than that of the control side and plasma.

Some Factors Affecting Iodine Secretion in Milk

Summary A series of experiments was conducted to study the manner in which iodine enters cows' milk: (a) Eight cows averaging 23.2lb milk daily were paired with their identical twins in later lactation averaging 10.7lb. Iodine 131 was administered intravenously followed by seven-day collection periods; (b) milk secretion was stopped in the left udder halves of eight cows by allowing a 24-hr accumulation of milk, and the right halves were milked prior to intravenous administration of I 131 . Left and right udder halves were milked at 8- and 32-hr intervals thereafter for six days; (c) Iodine 131 was infused into the gland cisterns of six cows after the morning milking. Absorption of administered I 131 from the mammary gland into the blood stream was estimated from the percentage of the dose recovered in the milk during subsequent milkings. Results indicate that iodide passes easily in both directions between the cow's mammary gland and blood, and that it can enter the milk independent of milk secretion. Protein-bound iodine did not appear to transfer between blood and milk in either direction. It is indicated that iodide enters the cow's udder passively (regardless of secretory activity), but that once it is in the milk-collecting spaces, a portion of the iodine is bound in some manner and is not available for resorption. The greater iodine secretion of higher-yielding cows is related primarily to their greater volume of milk.

Chemical Composition of Mammary Gland During Experimental Mastitis

Summary Water, fat, Na, K, Cl, DNA, RNA, histamine, and glyeogcn were determined on sheep mammary gland samples to characterize the tissue changes occurring during the experimental induction of mastitis with Escherichia coli and Staphylococcus aureus . Inoculations were made on one-half of the udder and chemical changes determined during initial stages of inflammation. One-half to five hours after inoculation treated udder halves showed great increases in size and weight. This inflammatory response resulted in dilution of adipose tissue from 20% of total weight in the control to 10% in mastitic glands. Water content increased markedly, from 83 to 88%. The response appeared to be very similar in glands from either estrous or luteal phases of the reproductive cycle, while ovariectomized ewes showed a lesser response. Na and Cl increased greatly and K decreased, indicating an inflammatory edema. Histamine concentration of the inoculated glands decreased. The most dramatic change occurred in glycogen content, which increased three- to fourfold in inoculated glands. This glycogen response appeared to be correlated with leukocytic invasion. Chemical changes induced by S. aureus were not as marked as those occurring after E. coli infection.

Studies on the hormonal induction of mammary growth and lactation in the goat. II. Functional and morphological studies of hormonally developed udders with special reference to the effect of 'triggering' doses of oestrogen.

SUMMARY 1. Treatment of spayed virgin goats with oestrogen ('triggering'), following administration of oestrogen and progesterone for 150 days to cause udder development, had no significant effect on the milk yield or on the structure of their udders. 2. Daily injections of 0·5 mg hexoestrol plus 70 mg progesterone for 150 days with or without the final oestrogen 'triggering' treatment induced udders which were virtually free from histological abnormalities and in which the alveolar tissue was homogeneous and compact. The milk yields were reasonably uniform between goats, and the incidence and degree of asymmetry in milk yield between two halves of the udder were no greater than in normally lactating goats. 3. Treatment for 20 weeks with oestrogen alone at daily doses ranging from 0·025 to 0·25 mg grew glands characterized by histological abnormalities previously found in glands developed with higher doses of oestrogen, namely cystic alveoli, papillomatous outgrowths from the epithelium and immature lobules. There was no graded relationship between dose of oestrogen and milk yield, and asymmetry of yield between the two halves of an udder was marked and widespread, particularly in the goats receiving the lowest dose. 4. Total alveolar surface areas of half-udders removed at the peak of lactation were estimated by three related methods, all of which gave high correlations with the milk yields of these udder halves. With only one of these methods, however, was there an appreciable partial correlation between porosity index (surface area/unit volume) and milk yield.

Studies on the hormonal induction of mammary growth and lactation in the goat.

Extensive morphological and functional investigations have been carried out on the artificial induction of mammary development and lactation in the goat using hexoestrol alone and in combination with progesterone, at several dose levels and proportions. Administration of the oestrogen and progesterone was either by tablet implantation or by subcutaneous injection in oily solution. Forty animals were used, of which twenty-three were ovariectomized during infancy. Special histological techniques were devised for studying and estimating quantitatively the degree of mammary development. In the later experiments this was achieved by surgically removing one half of the udder, i.e. one gland, when the lactation curve had reached a maximum. In three normally lactating goats the operation had no influence on the milk yield of the remaining gland. For the dose levels used, the milk yields of the animals receiving oestrogen and those receiving oestrogen and progesterone did not differ significantly. In general, the artificially induced milk yields were below the expected yields had the animals come into lactation after kidding. It appeared highly probable that the total area of secretory epithelium in the artificially developed gland was less than in the normally developed udder. A high correlation was observed between the surface area of the secretory epithelium in the entire half udder and the milk yield. Several marked abnormalities were observed in the microscopic structure of the udders. These were less evident in the glands of the goats receiving progesterone provided the oestrogen dose was not excessive.