Pregnancy Obstructs Involution Stage II of the Mammary Gland in Cows: General Biological Implications

*Background*
Repeated research findings over the last 4 decades show that involution of mammary glands in dairy cows did not regress to same extend as that noticed in other mammalian species.

*Methodology/Principal Findings*
We took an advantage of a rare event in the normal modern dairy farming: A cow that was false-positively identified as being pregnant was "dried up" (i.e., induced into involution) conventionally about 60 before her expected parturition. This cow was culled, and samples of her mammary gland tissue were examined for gross histology. In this study we demonstrate for the first time that modern dairy cow may undergo extensive obliteration of the lobular-alveolar structure, as expected in involution stage II. 

*Conclusions/Significance*
We conclude that lack of histological evidence for the appearance of involution stage II in the vast majority of modern cow's population is related to the peculiar modern dairy husbandry, in which dairy cows are induced into involution still pregnant. Because retardation of involution stage II in pregnant mammals is most likely a general physiological phenomena, it might occurs in other mammals, particularly in lactating humans. Thus, based on basic comparative physiology considerations, we suggest that concurrent lactation and pregnancy should be considered as an independent risk factor for breast cancer

An evaluation of casein hydrolyzate in combination with antibiotic for bacterial cure and subsequent increase in milk yield in dairy cows

<p>Abstract</p> <p>Background</p> <p>A 3-yr study examined whether prepartum treatment with casein hydrolyzate in combination with antibiotic, as routinely used in Israel for dry cow therapy, improved bacterial cure and increased milk yield in subsequent lactations in comparison with treatment with antibiotic alone. The vast majority of bacterial isolates in samples collected prior to drying-off comprised coagulase-negative staphylococci, mostly as <it>Staph. chromogenes</it>.</p> <p>Results</p> <p>Bacterial cure associated with the combined treatment was 73.8% in cows, significantly higher than the 51.7% cure recorded when cows were treated only with antibiotic. During the study, the annual milk yield of non-casein hydrolyzate treated and treated control cows increased at ~2% per year, which is consistent with the national annual increase attributed to genetic selection. In cows treated with casein hydrolyzate the increase was 9% (above the 2% expected) in the first lactation after the treatment, and 6.3% (above the 4% expected for 2 years) in the second lactation after treatment. These increases were significantly higher than those in the controls and those expected through genetic improvement.</p> <p>Conclusions</p> <p>Treatment with casein hydrolyzate at dry-off was shown to be a viable mean to eliminate existing environmental bacterial infection, and to improve milk yield in the next lactation.</p

Acute heat stress brings down milk secretion in dairy cows by up-regulating the activity of the milk-borne negative feedback regulatory system

<p>Abstract</p> <p>Background</p> <p>The objective of this study was to determine if acute heat stress (HS) decreases milk secretion by activating the milk-borne negative feedback system, as an emergency physiological response to prevent a life-threatening situation. To induce HS, summer acclimatized dairy cows were exposed to full sun under mid-summer Mediterranean conditions, with and without conventional cooling procedures.</p> <p>Results</p> <p>Exposure to HS induced a rapid and acute (within 24 h) reduction in milk yield in proportion to the heat load. This decrease was moderated by cooler night-time ambient temperature. The reduction in milk yield was associated with corresponding responses in plasminogen activator/plasminogen-plasmin activities, and with increased activity (concentration) of the (1–28) N-terminal fragment peptide that is released by plasmin from β-casein (β-CN (1–28)). These metabolites constitute the regulatory negative feedback system. Previously, it has been shown that β-CN (1–28) down-regulated milk secretion by blocking potassium channels on the apical aspects of the mammary epithelial cells.</p> <p>Conclusion</p> <p>Here we demonstrate that the potassium channels in mammary tissue became more susceptible to β-CN (1–28) activity under HS. Thus, the present study highlighted two previously unreported features of this regulatory system: (i) that it modulates rapidly in response to stressor impact variations; and (ii) that the regulations of the mammary epithelial potassium channel sensitivity to the inhibitory effect of β-CN (1–28) is part of the regulatory system.</p

The Interrelationships between Lactose Intolerance and the Modern Dairy Industry: Global Perspectives in Evolutional and Historical Backgrounds

Humans learned to exploit ruminants as a source of milk about 10,000 years ago. Since then, the use of domesticated ruminants as a source of milk and dairy products has expanded until today when the dairy industry has become one of the largest sectors in the modern food industry, including the spread at the present time to countries such as China and Japan. This review analyzes the reasons for this expansion and flourishing. As reviewed in detail, milk has numerous nutritional advantages, most important being almost an irreplaceable source of dietary calcium, hence justifying the effort required to increase its consumption. On the other hand, widespread lactose intolerance among the adult population is a considerable drawback to dairy-based foods consumption. Over the centuries, three factors allowed humans to overcome limitations imposed by lactose intolerance: (i) mutations, which occurred in particular populations, most notably in the north European Celtic societies and African nomads, in which carriers of the lactose intolerance gene converted from being lactose intolerant to lactose tolerant; (ii) the ability to develop low-lactose products such as cheese and yogurt; and (iii) colon microbiome adaptation, which allow lactose intolerant individuals to overcome its intolerance. However, in a few examples in the last decade, modern dairy products, such as the popular and widespread bio-cultured yogurts, were suspected to be unsuitable for lactose intolerant peoples. In addition, the use of lactose and milk-derived products containing lactose in non-dairy products has become widespread. For these reasons, it is concluded that it might be important and helpful to label food that may contain lactose because such information will allow lactose intolerant groups to control lactose intake within the physiological limitations of ~12 g per a single meal

The Interrelationships between Lactose Intolerance and the Modern Dairy Industry: Global Perspectives in Evolutional and Historical Backgrounds

Humans learned to exploit ruminants as a source of milk about 10,000 years ago. Since then, the use of domesticated ruminants as a source of milk and dairy products has expanded until today when the dairy industry has become one of the largest sectors in the modern food industry, including the spread at the present time to countries such as China and Japan. This review analyzes the reasons for this expansion and flourishing. As reviewed in detail, milk has numerous nutritional advantages, most important being almost an irreplaceable source of dietary calcium, hence justifying the effort required to increase its consumption. On the other hand, widespread lactose intolerance among the adult population is a considerable drawback to dairy-based foods consumption. Over the centuries, three factors allowed humans to overcome limitations imposed by lactose intolerance: (i) mutations, which occurred in particular populations, most notably in the north European Celtic societies and African nomads, in which carriers of the lactose intolerance gene converted from being lactose intolerant to lactose tolerant; (ii) the ability to develop low-lactose products such as cheese and yogurt; and (iii) colon microbiome adaptation, which allow lactose intolerant individuals to overcome its intolerance. However, in a few examples in the last decade, modern dairy products, such as the popular and widespread bio-cultured yogurts, were suspected to be unsuitable for lactose intolerant peoples. In addition, the use of lactose and milk-derived products containing lactose in non-dairy products has become widespread. For these reasons, it is concluded that it might be important and helpful to label food that may contain lactose because such information will allow lactose intolerant groups to control lactose intake within the physiological limitations of ~12 g per a single meal