In this short Research Reflection I address and refute the suggestion that oestrogens consumed in milk might contribute in a significant way to endogenous levels and thereby have a physiological action, possibly resulting in adverse consequences including increased breast cancer risk. Quantitative analysis based on published data shows that, even in worst case scenarios, oestrogen consumption in milk is considerably less than regulatory bodies regard as entirely safe.

Previous evidence suggests that the lactase gene C/T− 13910 polymorphism (rs4988235) is associated with avoidance of milk products and lower Ca intake. We examined whether the consumption of milk and milk products and the intakes of milk nutrients differ between the lactase genotypes from childhood to young adulthood. Subjects belong to the Cardiovascular Risk in Young Finns Study where the first cross-sectional surveys were conducted in 1980 (n 3596), with follow-up studies in 1983, 1986, 1989, 1992 and 2001 (n 2620). The same dietary questionnaire was used throughout the follow-up to collect data on habitual consumption of milk and milk products in all subjects, and daily nutrient intakes were assessed with 48 h dietary recalls in 50 % of the subjects. Subjects with the lactase non-persistence (C/C− 13910) genotype consumed less milk since childhood, but the consumption of other milk products did not differ between the genotypes. In adult females, the lactose content of milk products consumed was lower (P = 0·003), and in both sexes low-lactose and milk-free diets were more common in the C/C− 13910 genotype than in the other genotypes. Inadequate Ca intake was most common in females with the C/C− 13910 genotype as early as in childhood (15–63 %), but in males only in adulthood (24 %). In adult females, preference for low-lactose milk and milk products equalised the differences in Ca intake between the genotypes. Thus, in those with the C/C− 13910 genotype, preference for low-lactose milk and milk products may decrease the risk for inadequate Ca intake.

We determined milk intake and growth rate of fat-tailed Awassi ram lambs from birth to 30 days of age when sucking ewes that were grazing natural green pasture in the semi-arid Negev. The conversion of milk and energy intake to body mass and body solids gain in the lambs were calculated. Annual rainfall and, as a consequence, pasture availability were below average during the study. Body mass at birth was 4·22 (s.d. 0·71) kg and at 30 days was 12·10 (s.d.1·22) kg for an average daily gain of 256 (s.d.33) g/day. Of the 256 g/day, 100 (s.d.12·3) g/day were body solids, and for every unit body mass increase, proportionately 0·391 was body solids. Milk and energy intakes averaged 1·34 (s.d.0·23) l/day and 5·66 (s.d.0·97) MJ/day, respectively. The volume of milk intake per kg increase in body mass and body solids were 5·2 l and 13·4 l, respectively, whereas, the energy intake per kg increase in body mass and body solids were 22·1 MJ and 56·6 MJ, respectively. Of the total metabolizable milk energy intake, proportionately 0·46 was converted to body energy of the lamb. Although dry matter intake of the ewes was insufficient to prevent body mass loss, they produced sufficient milk to support a relatively high lamb growth rate, presumably by mobilizing fat reserves in the tail.

In each of two experiments, 36 3 to 5-day-old dairy calves (male and female), were allotted to one of three groups: warm housing, milk feeding in teat-buckets twice a day (group 1); warm housing and computer-controlled milk feeding (group 2); and cold housing and computer-controlled milk feeding (group 3). The experiments were conducted from September until February. The daily gain in the first 4 weeks was lower for the calves in group 3 in both experiments and for calves in group 2 in experiment 2 because of lower food intake in this period. This was compensated for by an increased gain later. In spite of the different method of milk feeding, the activity rhythm was nearly equal among groups, but at week 6 and 10 the calves in group 1 spent more time with the head over the feeding table than the calves in the two other groups. The number of unrewarded visits per calf to the milk feeding station decreased from over 30 at week 4 to around 20 shortly before weaning. The frequency of sucking/licking pen-mates was almost negligible in all groups. In order to reduce the heat loss, the frequency of calves lying with body contact clearly increased by decreasing ambient temperature in cold housing.

Forty-five Friesian × zebu crossbred calves (4 days old) were used to evaluate the effect of feeding different levels of whole milk and weaning at different ages. A total of 252 I whole milk offered over 12 weeks was compared with a feeding level of 134 I milk offered over 8 weeks. Water given ad libitum was also compared with allowing access to water once daily. The calves were penned and fed individually. The average daily gain of the calves weaned at 12 weeks was 464 g compared with 378 g for the calves weaned at 8 weeks of age and allowed access to water once daily and 422 g for the calves weaned at 8 weeks and given water a d libitum. Feeding extra milk and weaning at 12 weeks decreased the intake of concentrates and significantly (P < 0·05) increased live-weight gain. Allowing ad libitum access to water was associated with an increase in concentrate intake but this was not reflected in a significant increase in animal performance.