Increasing preweaning milk replacer supply affects postweaning energy metabolism of Holstein male calves.

Male Holstein calves commonly receive minimal quantities of milk replacer (MR) to speed up weaning and reduce costs. Studies with Holstein female calves show that early life feed restriction affects energy metabolism later in life. Aiming to test this hypothesis, 120 Holstein bull calves (48.4 ± 2.2 kg of BW and 20 ± 3.2 d of age) housed in 24 pens were blocked and randomized to two treatments: A low calf MR allowance (LP) (two daily doses of 2 l each, 582 g/d of DM), or a high MR allowance (HP) (two daily meals of 4 l each, 1164 g/d of DM). Calves were weaned at day 49 of the study and slaughtered at 32.8 ± 0.5 weeks of age. Throughout the study, animals had ad libitum access to a common compound feed, straw, and water. Twenty-four animals were randomly selected for an intravenous glucose tolerance test (IVGTT). The IVGTT was performed at week 6 and 12 of the study and consisted of an intravenous glucose infusion and sequential blood sampling up to 90 min after glucose infusions. Calves were heavier for HP until week 12, after which the difference disappeared. By design, the MR intake was higher in the HP group resulting in a higher energy intake and a higher average daily gain in the preweaning phase. Blood glucose curves were not different at week 6, but at week 12, 5 min after the infusion, glucose was higher in HP calves. Insulin curves were not different at week 6. Nevertheless, in week 12, a higher insulin concentration was observed for HP 5, 10, 15, 20, 30, 35, and 45 min' postinfusion, indicating a higher requirement of insulin to control glycemia. Differences between HP and LP calves were also observed for the quantitative insulin sensitivity check index, maximum insulin concentration, and insulin delta at week 12. Blood glucose reached maximum concentration within 5-10 min of the IVGTT test, and the concentration was, on average, 8.58 and 10.80 mmol/l at weeks 6 and 12, respectively. Insulin reached maximum concentration within 10-15 min of the IVGTT, and concentrations were, on average, 33.32 and 32.61 µUI/ml at weeks 6 and 12, respectively. Doubling MR supply improved animal growth up to weaning, but these differences disappeared by the end of the feeding period. Despite similar responses to glucose infusions preweaning, higher milk supply seemed to decrease insulin sensitivity after weaning.

Relationship between facial asymmetry and judging trustworthiness in faces.

Nonverbal facial signals provide valuable information for successful social interactions. Previous findings showed left-right facial asymmetry in attractiveness, smiling, and health in faces, and here we investigated the asymmetrical status of trustworthiness. Pairs of left-left and right-right faces from 38 photographs were viewed by participants who judged which member of the pair looked the most trustworthy. The results were compared to attractiveness and smiling judgements (Zaidel, Chen, & German, 1995). We found that trustworthiness was more related to attractiveness than to smiling in the women's faces, but no significant asymmetry for trustworthiness was found; in the men's faces, trustworthiness was neither related to attractiveness nor to smiling, nor was there a significant asymmetry. Taken together, trustworthiness as a facial display is complex; even when it appears to confirm the "halo effect", its expression is not strongly left-right asymmetrical in contrast to attractiveness or smiling.

Brain and face: communicating signals of health in the left and right sides of the face.

In human communication and mate selection the appearance of health sends signals regarding biological fitness. We compared the appearance of health in the sides of the face to previous results on left-right facial asymmetry in the appearance of beauty (1). The stimuli were created by aligning the left and right sides of the face each with its own mirror image. Here, participants viewed 38 pairs of left-left and right-right faces and judged which member of the pair looked healthier. No significant interaction emerged between decision (health vs attractiveness) and face side. Rather, in women's faces right-right was significantly more healthy and attractive than left-left, while in men's faces there was no significant left-right difference. In biology and evolution, health and beauty are closely linked and the findings here confirm this relationship in human faces.

Functional asymmetry in the human face: perception of health in the left and right sides of the face.

The expression of health on the human face, like beauty or emotions, is an important biological display. Previous findings of left-right functional asymmetry in facial attractiveness and the linkage of attractiveness and health in evolutionary biology notions have prompted the present study. A total of 38 pairs of left-left and right-right facial composites were viewed by 24 subjects on a computer screen, and the task was to decide which member of the pair looked healthier or there was no difference. The results revealed a significant interaction between face side and sex of face. Right-right composites of women's faces were judged significantly healthier than left-left, whereas in men's faces, no significant left-right difference emerged. As these results parallel previous findings of attractiveness in the identical set of faces, we propose that evolutionary biology notions linking the appearance of health and of attractiveness apply to the human face as well.