Abstract: Studies were undertaken to determine the progressive changes and relationships between the major constituents in the mammary secretion of breast feeding and non-breast feeding women during the initiation of lactation. The concentration of metabolites (lactose, glucose and urea), electrolytes and proteins (total protein, alpha-lactalbumin, lactoferrin, albumin, IgA, IgG and IgM) were measured in small samples of mammary secretion (0 . 5-5 . 0 ml). Colostrum during late pregnancy contained higher concentrations of proteins and lower concentrations of metabolites than milk in established lactation. Of the electrolytes, the concentrations of sodium, chloride and magnesium were higher, whereas potassium and calcium were lower in colostrum than in milk. The osmolality of the secretion remained relatively constant over the pre-partum and post-partum period. These findings showed that the initiation of lactation developed in two phases, first a limited secretion of milk constituents in late pregnancy and then true induction of lactation (lactogenesis) 32-40 h after delivery. The changes in the mammary secretion of non-breast feeding women during the first 3 days post-partum were similar to those observed in breast feeding women but reversed abruptly during the next 6 days, indicating the onset of mammary involution. This finding demonstrated that breast feeding is not a major factor for the initiation of lactation but is essential for the continuation of full lactation.

Abstract: PRL involvement in periparturient mammary development and onset of milk secretion was studied in 17 multiparous, monotocous Holstein cows. Mammary glands were obtained 10 days prepartum from untreated cows and 10 days postpartum from untreated cows and cows treated with CB154 (2-Br-α-ergokryptin) or CB154 plus PRL. CB154 was administered for 12 days before expected parturition through 10 days postpartum. PRL was infused continuously for 6 days immediately before parturition in cows receiving CB154 plus PRL. Treatment with CB154 reduced basal serum PRL concentrations approximately 80% and blocked the normal surges in serum PRL concentrations at parturition and during milking. Average milk production in cows given CB154 alone was 11.4 kg/day lower than in controls. Periparturient infusion of PRL in cows treated with CB154 (CB154 plus PRL) prevented reductions in milk production. Treatment with CB154 had no effect on feed intake or periparturient serum concentrations of GH, progesterone, and glucocorticoids....

Abstract: Concentrations of LH, FSH, prolactin, estrogen, and progesterone were measured in blood samples collected at various intervals during and immediately following lactation to determine the role of the ovary in controlling gonadotropin and prolactin secretion and initiation of estrous cycles in the pig. Ten primiparous sows were ovariectomized (ovex, n = 5) or left intact (n 5) 2 to 4 days after farrowing. Serum progesterone and estrogens in samples collected daily during lactation were not different between intact and ovex sows. Serum FSH increased immediately after ovariectomy and remained elevatedduring lactation,but LH concentrations were similar between ovex and intact sows. Both LH and FSH were higher during the last 2 weeks of lactation than during the first 3 weeks. On Days 10 and 20 of lactation, all sows received (i.v.) two challenges of gonadotropin releasing hormone (GnRH; 400 �g each) at 135 mm intervals. Peak change (maximum value minus baseline) in FSH after GnRH was higher in ovex than in intact sows on both Days 10 and 20. Peak change in FSH in ovex rows was higher on Day 20 than on Da� 10, but peak change in FSH in intact rows was similar between Days 10 and 20. Peak change in LH after GnRFI was similar between ovex and intact sows. Peak change in LH after the second GnRH challenge on Day 10 was higher than that after each of the other three challenges. Although serum prolactin concentrations in selected samples collected on Days 10 and 20 were not significantly different between treatment groups, intact sows had consistently higher concentrations compared with ovex sows. Separation of four sows from their litters for 4 h during the last week of lactation resulted in a decline in serum prolactin, but prolactin increased fivefold within 15 mm and tenfold during the second hour after piglets were replaced. In contrast, LH did not change prior to or after piglets were allowed to nurse. After weaning, concentrations of estrogens peaked during 24 h around onset of estrus prior to

Abstract: 1. In two experiments measurements were made of food intake, live-weight change, milk yield and milk composition in early lactation when dairy cows were given diets containing varying proportions of protein as fish meal (low rumen degradability) or as groundnut meal (high rumen degradability). In a preliminary trial measurements were also made with cows given supplements of either fish meal or barley and fed at a restricted level of feeding. 2. When metabolizable energy (ME) intake exceeded 160 MJ/d there was no evidence of responses to changes in protein degradability, ut at ME intakes below 135 MJ/d increases in the supply of undegradable protein led to increases in fat-corrected milk yield, protein content and live-weight loss. 3. The interaction between energy intake and protein degradability is unexpected because net protein:net energy requirement increases as milk yield increases, but may be explained in terms of differential effects of changing rumen outflow rates on degradabilities.

Abstract: Milk composition and milk intake were measured in lean and preobese Zucker rat pups. Lactating dams were injected with 3H2O, which equilibrated with plasma water within 30 minutes. A constant specific activity of 3H was maintained by adding 3H2O to drinking water. Blood samples of 5 microliters were obtained from 1, 15 and 20-day-old suckling pups every 4 hours for a 24-hour period and the accumulation of tritium was used to calculate pups' milk intake. No diurnal variation in milk intake of pups was observed. Obese pups were identified at 5 weeks of age and showed no difference in milk intake compared to lean littermates at 10, 15 and 20 days of age. Milk intake of pups increased with age from 2.0 ml at day 10 to 15.8 ml by day 20. Food and water intake of dams also increased from day 10 to 20 of lactation. The protein and carbohydrate component of rat milk did not change significantly from day 5 to 20 of lactation; however, the fat component decreased significantly from 12.7% at day 5 to 4.2% at day 20.

Abstract: 1. Milk productions and 7 d dietary records were determined on twenty-seven mothers who had been breast-feeding for 1, 3, 6, 9, 12 or 15 months. 2. The mean milk productions for each group of mothers was 1 . 87, 1 . 238, 0 . 884, 0 . 880 and 0 . 951 kg/24 h at 1, 3, 6, 9, 12 and 15 months of lactation respectively. There was no significant difference between two milk determination 3--7 d apart on each mother or between the mean milk production of each group of mothers. 3. Energy intakes of the infants was found to be higher than the usually-accepted values at 1 and 3 months of age but by 6 months were similar to the accepted normal values. 4. Energy intakes of the mothers although greater than those recommended for similar non-lactating women were not sufficient to take into account the energy content of the milk.

Abstract: The acid-soluble ribonucleotides of cow's, goat's and sheep's milks were measured by enzymic and ion-exchange chromatographic procedures at different stages of lactation. Colostra and milk from ruminant species contained orotic acid and 13 well-identified nucleotides: AMP, CMP, GMP, UMP, UDP, GDP, UDP-glucose, UDP-galactose, UDP-N-acetyl-glucosamine, UDP-N-acetyl-galactosamine, UDP-glucuronate, GDP-mannose and GDP=fucose. Cow's goat's and sheep's colostrum contained significant amounts of nucleotides, which increased in amount from the moment of parturition, to reach a maximum 24--48 h later. The nucleotide concentration decreased thereafter with advancing lactation. Cow's milk contained substantial amounts of orotic acid, which increased during lactation, whereas in goat's and sheep's milk no increase took place. The cytidine and adenosine derivatives in ruminants' milk did not change significantly during lactation. The UDP-glucose/UDP-galactose ratio was measured in ruminants' milk at different stages of lactation.

Abstract: Twenty-five mature Finnish Landrace × Dorset Horn ewes, each suckling two lambs, were used to measure the effects of dietary concentration of crude protein on food intake, milk yield and changes in body composition during the first 6 weeks of lactation. Diets were complete mixes of milled hay and concentrates, and the amounts of barley and fish meal were altered to give crude protein concentrations of 116 and 143g/kg dry matter. Ten ewes were slaughtered at 5 to 7 days of lactation and the remaining ewes were slaughtered at 40 to 43 days of lactation.The higher concentration of crude protein in the diet did not alter food intake or digestion. Milk yield was not altered in the first 3 weeks of lactation but was increased in weeks 4 and 5 (P<0·05). Production of milk protein was increased by a higher protein concentration in the diet (P<0·01) and this effect was evident from the 2nd week of lactation. Weight of chemically determined fat in the body decreased from 179 to 13-0kg from 6 to 42 days of lactation (P<0·001) for ewes on diets of both concentrations of crude protein.It was concluded that the higher level of protein intake during early lactation increased yields of milk and milk protein. The data suggest that the energy lost from the body was used more efficiently by ewes given the diet of high, rather than low, protein content.

Abstract: Milk and mineral intakes of twenty-six full term infants receiving human milk as their sole milk source were determined by "test weighing" and direct analyses of milk samples at months 1, 2 and 3 of lactation. Data indicate that volume of milk ingested ranged from 295 to 996 ml/day and mean intakes (606, 601, 626 ml/day at months 1, 2 and 3, respectively) are less than the often quoted 850 ml/day. Taking into account Swedish and Scottish data and that from the present investigation, it appears that typical human milk intakes are 500 to 800 ml/day. No relationship was observed between volume of intake and growth of infants. Ranges of intake for copper, iron, zinc, calcium, phosphorus, magnesium, sodium, potassium and chloride are comparable to values reported for these mineral intakes by both early and modern investigators even though different data collection techniques and analytical methods were employed.

Abstract: • Induced lactation is breast-feeding without prior pregnancy. Preparation includes breast and nipple stimulation, supplementing the maternal diet, and occasional use of hormones. Infants younger than 8 weeks are more willing to nurse than infants older than 8 weeks. Previous lactation experience is related to increased likelihood of milk production, decreased need for supplemental fluids, and duration of breast-feeding. Tandem nursing an older biological infant and the adoptive infant does not guarantee an increase in milk production sufficient to meet the adoptive infant's needs. Three fourths of the women who took part in this questionnaire survey evaluated their experience positively, regardless of infant age at weaning or need for supplemental fluids. Most respondents stressed the maternal-infant relationship and its enhancement through breast-feeding, rather than milk production, as the reason for attempting induced lactation. ( Am J Dis Child 1981;135:340-343)

Abstract: A positive correlation was observed between the midcycle elevation of estrogen (E) and the level of oxytocin- and estrogen-stimulated neurophysin (ESN), the protein carrier of oxytocin, in the plasma of five of six women The time of the maximal level of E was associated with a level of oxytocin significantly greater than that in either the early follicular or late luteal phase (P less than 0025) Likewise, the level of ESN at midcycle was greater than the level of ESN in the early follicular or late luteal phase (P less than 001) Other than states of lactation or pregnancy, this is the only described cyclic secretion of oxytocin in humans Since oxytocin chronologically correlates with a rise in the level of E at midcycle, a role for oxytocin in ovulation may be considered

Abstract: A heterologous double-antibody radioimmunoassay was used to measure plasma prolactin concentrations in 27 marmosets. The assay was valid for the marmoset because plasma levels of prolactin were increased in response to TRH and metoclopramide and suppressed in response to bromocriptine treatment. During the cycle there were no consistent changes in plasma prolactin concentrations. During lactation mothers suckling single or twin infants had higher prolactin levels than did non-suckling females and levels were highest with twins. No statistically significant delay in the resumption of ovulation post partum was observed for the suckling and non-suckling females; conception occurred in all but one marmoset by 70 days post partum. These results show that neither the suckling stimulus nor high levels of prolactin post partum delay the return of ovulation and fertility in the common marmoset, a result in contrast to that for all other primate species so far investigated.

Abstract: Seven established cell lines, including both epithelial cells and fibroblasts (MDCK, Vero, CV-1, NRK, 3T3, F2408, and NIL8) and four early passage cell strains (bovine articular chondrocytes, bovine smooth muscle cells, human foreskin fibroblasts, and rat embryo cells) were cultured in serum-free medium supplemented with milk obtained 1 day after birth (colostrum) or 80 days after birth (older milk). MDCK, Vero, CV-1, NRK, and 3T3 grew readily in colostrum and attained saturation densities ranging from 22% to 63% of that in serum. There was no growth of F2408, NIL8, or the early passage strains in bovine colostrum. None of the 11 cell cultures grew in older milk. The temporal dependence of growth in milk was examined in detail using MDCK cells. Growth equivalent to that in serum occurred in 3% colostrum and in 15% milk obtained 2 days after birth. Milk obtained 3 days and 10 days after birth was not effective as a growth supplement for MDCK cells at any concentration. Those cells, unable to grow in colostrum or in older milk, could be induced to grow if culture dishes were precoated with fibronectin. In addition to fibronectin, it was necessary in some cultures to supplement colostrum or older milk with insulin and/or transferrin in order to achieve growth. In the presence of fibronectin and appropriate factors, the final saturation density attained in colostrum or older milk ranged from 25% to 100% of that in serum. The fibronectin contents of bovine colostrum and milk were determined. The fibronectin level of colostrum was found to be approximately 5% of bovine serum. There was no detectable fibronectin in the 80-day-old milk.