First Day Of Lactation Research Articles

Teat stimulation and milk production during early lactation in sows: Effects of continuous noise

The aim of the study was to investigate if the time or the intensity of the massage performed after let down by suckling piglets influenced the amount of milk produced by the teat receiving the massage and to study if the effects of continuous fan noise affected piglet milk consumption. Twelve Swedish Landrace × Yorkshire sows, six of them exposed to continuous fan noise, were studied together with their litters. On days 1–3 postfarrowing, the number of massage movements and the time each piglet was massaging was recorded in relation to milk letdown. The teat used by each piglet was noted and whether the piglet was urinating or defecating during the suckling. Piglets were weighed before and after each suckling and on days 7 and 14. The duration and intensity of teat stimulation given to a teat influenced the production of that teat during the first days of lactation in sows not exposed to noise. There was a tendency for the 3rd and 4th teat-pairs to respond less to the massage than the front or rear teat-pairs. Suckling piglets subjected to continuous loud noise performed less teat stimulation and the milk production of the sow was less. Key words: Pig, lactation, nursing, suckling, milk production

Some Events of Thyrotropin-Releasing Hormone Metabolism Are Regulated in Lactating and Cycling Rats

Levels of thyrotropin-releasing hormone (TRH), TRH mRNA and pyroglutamyl peptidase II were analyzed in the hypothalamus-adenohypophyseal axis during lactation and estrous cycle. Mediobasal hypothalamic levels of TRH dropped 41% (p less than 0.01) from pregnancy levels (taken as 100%) on the first day of lactation, recovering until day 15 to the values observed at pregnancy. A sharp decrease was also observed during weaning (36%, p less than 0.01 compared to last day of lactation). TRH levels in the neurohypophysis increased during lactation and dropped at weaning. Highest TRH mRNA levels in the paraventricular nucleus were found at the end of pregnancy and beginning of lactation; they decreased 37% (p less than 0.05) at day 5 of lactation and stayed constant thereafter. Pyroglutamyl peptidase II adenohypophyseal activity was not modified during lactation but changed during estrous cycle. Relative to estrous values, activity diminished 58% (p less than 0.05) at 10.00 h (57% at 14.00 h) during diestrus 2 and 27% at 10.00 h (37% at 14.00 h) during proestrus. Hypothalamic TRH mRNA levels fluctuated in an opposite manner to adenohypophyseal pyroglutamyl peptidase II during the estrous cycle with a peak at diestrus 2: 183% of the estrous value (p less than 0.05). These data point to a regulation of TRH metabolism in conditions where prolactin (PRL) secretion fluctuates. They also suggest a sharp release of TRH between the end of pregnancy and the first day of lactation and that translational efficiency or post-translational processing of TRH precursor in the paraventricular neurons (projecting to the median eminence) increases during lactation and drops at weaning, concomitantly with PRL secretion.

Comparative study of mammary gland development and differentiation between beef and dairy heifers

Sixteen Hereford and 16 Holstein heifers were used to study the relationship of milk production potential to mammary development and differentiation. Heifers were slaughtered 150, 180, and 260 days of first gestation and at 49 days of first lactation. Prolactin binding capacity of mammary tissue was 2.5 fold higher in dairy than beef heifers at day 260 of gestation (27.2 vs 11.0 fmols/mg protein). In both breeds, maximal growth hormone binding in liver coincided with the beginning of the rapid phase of mammary growth at 180 days. Mammary tissue from dairy heifers released more casein and alpha-lactalbumin during in vitro incubations than tissue from beef heifers. No differences were observed between breeds with respect to incorporation of [ 14C]acetate into lipids. Mass of dairy mammary tissue at 49 days of lactation was 3.3 times greater (16.4 vs 4.9 kg) and produced 5.7 times more milk (20.3 vs 3.5 kg/day) than its beef counterpart. The total DNA content and the RNA/DNA ratio of lactating dairy mammary tissue was approximately twice that of lactating beef mammary tissue. The data suggested that the higher milk production observed in dairy cattle is a result of a greater number of secretory cells and greater activity per cell.

Mammary gland whey acidic protein: ontogeny and changing patterns of steroid sensitivity

Whey acidic protein (WAP) has been measured by radioimmunoassay in the mammary gland of rats over pregnancy and lactation, and in mammary gland explants incubated with glucocorticoid or progestin in vitro. The radioimmunoassay used a novel fusion protein, glutathione transferase-WAP (GT-WAP), which can be iodinated with ease, unlike the native protein. Mammary gland WAP levels were low (< 100 ng/mg tissue) until 2–3 days before parturition, but rose to 3 μg/mg tissue at day 21 of pregnancy. Immediately after parturition WAP content decreased to 1 μg/mg tissue, and then increased to > 5 μg/mg tissue during mid-lactation. Similarly, α-lactalbumin content was low throughout pregnancy (< 10 ng/mg tissue) until day 20. Thereafter, values rose on the last day of pregnancy and the first day of lactation, fell briefly in early lactation like WAP, and rose to plateau levels by day 11 of lactation. In vitro expiants prepared from mid-pregnant rats (day 14) synthesized WAP in the presence of insulin and prolactin. The synthetic glucocorticoid RU26988 (11 β,17β-hydroxy-17α-(1-propynyl)-androsta-1,4,6-trien-3-one) progressively increased WAP production to a maximum of > 10-fold basal (in the presence of insulin and prolactin) at 300 nM, in contrast with a-lactalbumin which showed a biphasic dose-response curve in expiants from mid-pregnant rats. Expiants taken just prior to parturition (days 19 and 20 of pregnancy) showed increased basal production, but were markedly less responsive to RU26988; on day 1 of lactation RU26988 (300 nM) gave a small rise of 50% over basal levels, but by day 5 of lactation, RU26988 produced no increase over basal levels. As well as differing in its response to glucocorticoids, WAP production was considerably less sensitive to inhibition by the synthetic progestin ORG 2058 (16α-ethyl-21-hydroxy-19-norpregn-4-ene-3,20-dione) than was that of α-lactalbumin, further evidence for a complex pattern of control of milk protein production by steroid hormones.

Energetics of Pregnancy and Lactation in Freeranging Little Brown Bats (Myotis lucifugus)

We combined field measurements of metabolic rate, made with doubly labeled water, with data from our previous studies to examine reproductive energetics in 24 female little brown bats (Myotis lucifugus). Including estimates of tissue or milk production, M. lucifugus required an average of 33.7 kJ d⁻¹ of assimilated energy in pregnancy compared to 41.3 kJ d⁻¹ during lactation. Predicted insect consumption was 5.5 g d⁻¹ for a 9-gpregnant female and 6.7g d⁻¹ for a 79-g lactating female. About 2% of total energy assimilated during pregnancy was stored as new tissue, whereas lactating females exported 32% as milk. Estimated assimilated energy demand on the first day of lactation was 33.8 kJ d⁻¹ and increased to 60.3 kJ d⁻¹ at peak lactation. By subtracting laboratory measurements of roosting costs from observed metabolized energy expenditure, we calculated that foraging flight by 9-g pregnant M. lucifugus required 4.46 kJ h⁻¹; this was 13% less than allometric predictions. Foraging fight accounted for the largest proportion of the daily metabolized energy budget during pregnancy (61%) and lactation (66%). The large amount of energy devoted to foraging by this aerial-feeding bat may partially explain the low proportion of energy it allocates to tissue production and milk export.

Concentration of lactoferrin and transferrin throughout lactation in cow's colostrum and milk.

The evolution of the concentration of lactoferrin and transferrin was studied in cow's colostrum and milk throughout lactation. The highest concentrations of both proteins were found in the first milking (0.83 mg/ml for lactoferrin and 1.07 mg/ml for transferrin), decreasing sharply during the first days of lactation (colostral period). Thereafter, the concentrations of these proteins decreased slowly, reaching their definitive values during the third week post-partum (0.09 mg/ml for lactoferrin and 0.02 mg/ml for transferrin). The ratio transferrin/albumin in colostrum (first milking), mature milk, milk from mastitic cows and serum was determined, and found to be four times greater in colostrum than in mature or mastitic milk, suggesting a specific transport of transferrin from blood to milk.

Measurement by radioimmunoassay of casein content in rabbit mammary gland during pregnancy and after prolactin stimulation in organ culture.

A specific homologous radioimmunoassay was developed to measure rabbit beta-casein in rabbit mammary gland with a sensitivity of 0.5 ng/ml protein. It was used to measure casein concentration during pregnancy and in organ culture of mammary gland explants. Casein was detectable in virgin mammary glands, showed a small increase during the first half of pregnancy, increased more than 20-fold between Days 21 and 27, and diminished somewhat on the first days of lactation. After 24 hr of culture, mammary gland explants had no detectable casein, but the addition of increasing concentrations of prolactin to a culture medium which contained insulin (5 micrograms/ml) and cortisol (0.5 microgram/ml) induced a regular increase in the casein content of the tissue. Casein started to increase when 10 ng/ml of prolactin was present and maximal values were achieved for 100 ng/ml of the hormone.

Biochemistry of human milk in early lactation.

With the analysis of more than 550 human milk samples we showed that triglycerides (accounting for 96-99% of the total lipids) increased from 2 to 3.5 g/100 ml mainly during the first week postpartum and remained constant thereafter. In contrast, both cholesterol and vitamin E concentrations decreased from 35 to 20 mg/100 ml and from 1.7 to 0.30 mg/100 ml, respectively. The phospholipids remained constant (40 mg/100 ml). Also the fatty acid composition of total lipids changed. Mid chain fatty acids (C10, C12, C14) increased, whereas the long chain polyunsaturated fatty acids decreased. The P/S-ratio of 0.32 remained constant throughout lactation. The mean protein content of human milk decreased from approximately 2 g/100 ml at day 2 to approximately 1 g/100 ml at day 36 of lactation. The content of each individual amino acid decreased likewise. However, when we expressed the amino acid values in relation to the protein value--that is as g amino acid per g protein--some decreased, some remained constant and some increased indicating a changing protein pattern. From these data we computer-calculated a sharp decrease in IgA content, a moderate decrease for lactoferrin and constant values for casein and a-Lactalbumin. Throughout the whole period of investigation, non protein nitrogen accounted for about 20% of total nitrogen. Although the absolute values decreased according to total nitrogen, the sum of free amino acids, as well as the amount of taurine, remained constant. Lactose increased from about 4 g/100 ml to 6 g/100 ml during the first days of lactation. The calcium content increased from a mean value of 25 mg/100 ml at day 1 to 32 mg/100 ml at day 5 and remained constant at 30 mg/100 ml up to day 36. Phosphorus content increased from 10 mg/100 ml at day 1 to 17 mg/100 ml at day 8 and then continuously decreased to 13 mg/100 ml at day 36. The protein-bound part of the calcium remained constant during the period investigation, the fat-associated part increased from 11% to 26%. Protein-bound phosphorus decreased from 45% in colostral milk to 29% in transitional and 23% in mature milk.

DIFFERENCES BETWEEN SIRE GROUPS IN BODY MEASUREMENTS AND BODY WEIGHT CHANGES OF LACTATING COWS

Body weights and measurements of 694 first, 519 second and 329 third lactation cows in five Research Branch herds of the National Cooperative Dairy Cattle Breeding Project of Agriculture Canada were studied. The A line cows were daughters of U.S., Canadian and Finnish Ayrshire proven bulls, Brown Swiss and Norwegian Red proven bulls and young Research Branch Ayshire bulls and Research Branch Ayrshire cows. Highly selected U.S. and Canadian Holstein proven bulls and young Research Branch bulls mated to Research Branch Holstein cows produced the H-line cows. The model for analysis contained fixed effects for station, year of birth, line, sire group within line and sire within sire group within line as classification variables and age at calving as a covariable. Sire group, line, station and sire had significant effects on all weights studied. However, most effects were not significant for weight changes. Daughters of Brown Swiss and Norwegian Red sires were nearly as heavy as the daughters of Holstein bulls. On average, cows lost about 20 kg of weight from calving to 56 days postpartum of first lactation. The older first calvers were found to lose more weight from calving to 56 days of first lactation and gain less weight from 56 days postpartum onward than the younger first calvers. The effects of station, line and age at calving were significant for most body measurements. Sire group effects were significant for 13 out of 24 measurements. Significant differences between sire groups existed in stature (withers height) at all lactations and ages. In contrast, body length (shoulder to hook) did not differ significantly between sire groups from 112 days of first lactation onward. Key words: Body weight changes, body measurements, dairy cattle

Protease inhibitor levels in porcine mammary secretions.

The total trypsin inhibiting capacity (TIC), and the content of the individual protease inhibitors, both the specific colostrum protease inhibitor (SCTI) and the serum-type inhibitors, i.e., alpha 2-macroglobulin f and s, inter-alpha-trypsin inhibitor, alpha 2-antitrypsin and alpha 1-protease inhibitor, were quantified in porcine mammary secretions throughout lactation using immunoprecipitation methods. In addition, albumin, of serum origin, and beta-lactoglobulin, a milk-specific protein, were quantified and used as references. In presuckled colostrum, high levels of TIC, SCTI, albumin and beta-lactoglobulin were found, while the serum-type inhibitors appeared in amounts related to their molecular weights ranging from 3-6% of the adult serum levels for the macroglobulins to 42% for alpha 1-protease inhibitor. These parameters all decreased during lactation. The levels of TIC and SCTI especially decreased during the first days of lactation, and SCTI disappeared from milk after 5-7 days. Mature milk showed low TIC levels, about 0.1 IU/ml, which originated from the low amounts of the serum-type inhibitors (1-4% of the adult serum level). The levels of both alpha 2-macroglobulin f and s decreased less than albumin did in sow milk, while the other inhibitors decreased more or on the same order as albumin. A considerable variation in the amounts of the protease inhibitors between individuals and also between different teat secretions of the same sow, especially in colostrum, was evident. The possible physiological functions of the protease inhibitors in the mammary gland of the sow and in the gastrointestinal tract of her nursing offspring are discussed.

The suckling-induced rise of plasma prolactin in lactating rats: its dependence on stage of lactation and litter size.

The response of plasma prolactin in vigorous suckling was measured in lactating rats which had been isolated for 10-12 h from their offspring. Plasma prolactin was investigated during suckling at various stages of lactation. The results demonstrate that prolactin responds maximally to suckling already in the first days of lactation. In the second half of the lactation period, the prolactin rise in the plasma induced by suckling decreases gradually; this is not due to a reduced suck-intensity of older pups. A relationship is found between the height of the suckling-induced prolactin rise and litter size. The data suggest that during suckling in the first weeks of lactation the pituitary secretes large amounts of prolactin at a constant rate. It is speculated that in the first minutes of suckling, receptors may clear considerable amounts of released prolactin from the circulation.

Ovarian and adrenal steroids during pregnancy and the oestrous cycle in the rat.

Changes in adrenocortical function of the rat during the 4-day oestrous cycle and pregnancy were studied in vivo and in vitro. Regulation of adrenal production of progesterone and corticosterone was of particular interest. Morning (09.00 h) plasma concentrations of corticosterone were similar at each phase of the cycle, but a higher concentration was found in the afternoon (15.00 h pro-oestrus). However, the rate of progesterone utilization for corticosterone production by adrenal homogenates was essentially unchanged at all periods of the cycle. Therefore, the activities of the 21- and 11β-hydroxylating systems appeared not to be important determinants of plasma corticosterone levels (coefficient of determination (r2) = 0·06). These results indicate that adrenal secretion of progesterone is not specifically regulated during the cycle. On the other hand, resting plasma levels of corticosterone declined by 80–85% from the value on the morning of pro-oestrus between days 5 and 12 of pregnancy and then increased on day 22 and after parturition. These fluctuations did not result from alterations in the rate of metabolic clearance but rather, were closely coupled to the capacity of adrenal tissue to convert progesterone to corticosterone (r2 = 0·87). These findings suggest that progesterone utilization may be specifically curtailed at the expense of corticosterone production at days 5 and 12 of pregnancy. Concurrent measurements of adrenal venous progesterone and ovarian venous progesterone (under stressful conditions) showed that the adrenal gland secretes 2–10 times more progesterone than the ovary at all stages of the oestrous cycle, on day 22 of pregnancy, and on the first day of lactation. Thus, the adrenal gland is capable of secreting large amounts of progesterone which, if present at the appropriate time, may inhibit, delay or facilitate ovulation and onset of mating behaviour as described by other workers. Under such circumstances, however, progesterone secretion appears not to be specifically regulated but seems instead to be due to precursor spillover, since the proportionate secretion of corticosterone does not change.

NOCTURNAL PLASMA INSULIN LEVELS IN COWS WITH VARYING LEVELS OF PLASMA KETONE BODIES; RELATIONS TO PLASMA SUGAR AND ACETOACETATE

ABSTRACT The interrelations of plasma values of insulin, sugar and acetoacetate (AcAc) have been investigated on nocturnal blood samples from 544 dairy cows at different stages of lactation. A wide range of plasma levels was observed (plasma sugar 42–106 mg/100 ml, insulin 0.3–2.2 ng/ml, AcAc 0.05–27 mg/100 ml). Nocturnal samples were taken to exclude as much as possible variations in plasma components induced by feeding. The following correlations were found: sugar/insulin r = 0.45, P &lt; 0.001; insulin/AcAc r=–0.23 (P &lt;0.001); sugar/AcAc r=–0.61 (P &lt;0.001). The partial correlation between insulin and AcAc was not significant (r = 0.07) when glucose was eliminated. A simultaneous decrease in plasma insulin and sugar was found, hypoglycaemic cows having the lowest insulin levels. It is concluded that this decreased insulin level is probably of importance in facilitating lipolysis during hypoglycaemia, thus being a prerequisite for the development of ketosis. Ten cows were sampled twice, one sample being taken before partus and the other during the 45 first days of lactation. After the onset of lactation indications of a more diabetic metabolism was found. The mean plasma insulin level was reduced from 1.3 to 0.6 ng/ml; a significant fall in plasma sugar and a rise in AcAc was also observed. Nine samples from cows developing ketosis and 23 with elevated AcAc levels, but without clinical symptoms, were compared to 26 samples of cows with low AcAc levels from the same herds and in the same stage of lactation. The mean insulin levels were 0.42, 0.52 and 0.71 ng/ml, and sugar 50.5, 59.5 and 73.6 mg/100 ml, respectively. It is concluded that the low insulin values found in the samples from the ketotic cows were due to reduced glucose stimulation of the pancreatic β-cells.

GENETIC CONDITIONS OF COWS REPRODUCTIVE SYSTEMS DISEASES IN SUBPOPULATIONS

As a result of the studies, the relationship of reproductive traits with adaptability was revealed, which were characterized by low heritability and were subject to inbred depression. Selection rates increased from generation to generation by an average of 13.8 %, but did not always lead to changes in disease rates. The correlation coefficient between milk yield of cows during the first 305 days of lactation and service period was -0,227± 0,013 (F test of 5.2), the coefficient of the linear regression of service period on milk yield for 305 days of first lactation – 0,45±0,033. A positive correlation (r =+52±0,012) was revealed between the milk yield of full-aged cows during 305 days of lactation and the number of cows eliminated due to infertility. Genetic and environmental factors together exceeded the threshold of adaptability, so the body's ability to resist became weakened. The correlation coefficient for daughter-mother for the duration of the disease +0,33±0,022, age of animals at the beginning of the disease – +0,36±0,021. Coefficients of repeatability gynecological diseases in cows from the first to the second lactation + 0,807, from the second to the third + 0,892, from the first to the third – + 0,454. From the data obtained, it follows that heritability depends on factors, each of which has a relatively small impact on variability and is determined by many genes. Features with a threshold deviation are not related to the efficiency of selection by productivity. Gynecological pathologies in offspring arise under the influence of different alleles systems.

Studies on Maintaining the Lactational Diestrum after Early Litter Weaning

The litters of lactating rats were adjusted to 8 pups on the day of parturition (day 1 of lactation) and various methods of cervical stimuli were performed. The litters were weaned at regular intervals and vaginal smears were examined for the return of estrous cycles. Thirty percent of mothers who either were not suckled or were suckled for 48 hr showed diestrus smears for 10 days or more. Mothers whose litters were removed on days 6, 9, and 12 of lactation did not exhibit an extended diestrum. Mechanical stimulation of the cervix of mothers weaned on day 3 of lactation did not increase the incidence of extended diestrus from the controls; electrical stimulation, however, almost doubled the number responding (50 vs. 30%). If the initiation of vaginal smearing was delayed from the first day of lactation until the third, none of the animals had pseudopregnancy-like vaginal smears. Estradiol administration on day 1 of lactation resulted in 60% of the animals exhibiting an extended diestrum. Combining both estradiol injection and mechanical cervical stimulation resulted in a slightly lower percentage (40%). The suckling stimulus is believed to induce an acute pattern of prolactin secretion while cervical stimulation induces a chronic pattern. The summation of these two secretory patterns may be observed early in lactation.

Influence of Length of Dry Period on subsequent Lactation in the Rat1,2

Rats given a four-day dry period produced approximately 28 (P<0.01) and 10% (P>0.05) heavier litters between Days 8 and 16 of lactation than rats given zero-day or longer (8, 12, or 16 days) dry periods, respectively. On the first day of lactation mammary glands of rats given an eight- or zero-day dry period contained 14% (P<0.05) more DNA (cell numbers) than glands of rats given other length dry periods. However, on Day 8 or 16 of lactation mammary DNA of rats given zero- or 16-day dry periods was significantly less than DNA of rats given four- or eight-day dry periods. Length of dry period had no detectable effect on RNA/DNA ratios (metabolic activity). Apparently, the effects of dry period length on lactation are associated with factors regulating cell numbers during the subsequent lactation rather than with factors affecting synthetic activity of the remaining mammary cells. Rats given zero- or 16-day dry periods contained less hydroxyproline (collagen) on the first day of lactation than rats receiving the optimal dry period. If collagen is necessary for future mammary development, these lower amounts in zero- and 16-day dry period groups could be one reason these glands contained reduced numbers of cells in later lactation. Dry period length did not affect hexosamine (ground substance) during early lactation, but during late lactation there was a linear increase with increasing length of the dry period.

Deoxyribonucleic acid content and proliferative activity of rabbit mammary gland epithelial cells

The DNA contents of individual nuclei of rabbit mammary gland epithelial cells at various physiological stages of development were measured with a microspectrophotometer. The results showed the Feulgen nucleal reaction to be a reliable method for quantitative work and reproducible when carried out under standardized and rigidly controlled conditions. The DNA contents of nuclei of the epithelial cells are not equal. Significant differences in DNA content per nucleus were present among individual animals, among glands of the same animal, and among areas within the glands. The proliferative activity of the cells was studied by the administration of tritiated thymidine to the rabbits 1 h before they were sacrificed. Radioautography of the mammary gland tissue was carried out to detect incorporation of thymidine into nuclei that synthesize DNA. It was found that a considerable proliferative activity takes place in the adult virgin rabbit. The largest proliferative activity occurs during the first half of pregnancy. Proliferative activity exists during the second half of pregnancy, but at the slower rate. The activity increases markedly one day prior to parturition, though it is somewhat lower than that during the first part of pregnancy. The high rate of proliferative activity continues during the day of parturition. A sharp drop occurs on the first day of lactation and remains low during lactation. There appeared to be a relationship between the DNA content per nucleus and the secretory activity of the cell. The content was high at times of high secretory activity and low at times of secretory quiescence. An inverse relationship between the proliferative activity and the quantity of DNA per nucleus also existed. The presence of non-genetic DNA in excess to the genetic diploid quantity is suggested. This additional DNA is postulated to be responsible for the increased DNA content per nucleus and may play a role in the secretion process.

Desoxyribonuclease activity of rat mammary gland during pregnancy and lactation.

SummaryDNA'ase activity was determined in late pregnancy and in early and late lactation in conjunction with measurement of acid-soluble nucleotides. DNA'ase activity was correlated with increased acid-soluble nucleotides during pregnancy and latter stages of lactation. There was, however, on first day of lactation an increase in enzyme activity and a decrease in acid-soluble nucleotides suggesting an increased catabolism of these products in early lactation for use in secretory process.

Deoxyribonucleic acid (DNA) content of mammary gland during pregnancy and lactation.

SummaryA study of the DNA concentration per nucleus was carried out on kidney and spleen and the developing and lactating mammary glands of rats. The DNA concentrations remained within normal values in the pregnant and non-pregnant stages. On the first day of lactation there was an abrupt drop in this value which returned approximately to normal by 18th day of lactation.

The Vitamin A and Vitamin C Content of Sows' Colostrum and Milk

The vitamin A and vitamin C levels of colostrum and normal milk are reported for ten sows carried through growth and gestation on pasture and for ten sows carried through growth and gestation in dry-lot. The sows were milked manually after the injection of 1 ml. of Pitocin, on the first day of lactation, the third day, the first, week, and each subsequent week until weaning at eight weeks of age. The mean values for vitamin A are: first and third day colostrum from pasture sows 143.6 γ/100 ml., from dry-lot sows 132.9 γ/100 ml.; normal milk from pasture sows 52.7 γ/100 ml., from dry-lot sows 34.8 γ/100 ml. of milk. The mean values for vitamin C are: first day colostrum from pasture sows 18.8 mg./100 ml., from dry-lot sows 24.6 mg./100 ml.; normal milk from pasture sows 10.4 mg./100 ml., from dry-lot sows 12.2 mg./100 ml. of milk.