Effect of milking frequency on lactation persistency and mammary gland remodeling in mid-lactation cows.

The objective of this study was to evaluate the effect of milking frequency on milk production and composition, mammary cell proliferation, apoptosis, and gene expression. For this investigation, 10 Holstein cows that were being milked twice a day in mid lactation were selected. To study the effect of differential milking, 2 quarters were milked once daily and the other 2 were milked thrice daily for 8wk.

Local control of mammary involution: is stanniocalcin-1 involved?

There is considerable evidence to indicate the existence of local control of mammary gland involution, but the exact nature of this control has yet to be defined. Stanniocalcin-1 (STC-1) is a newly discovered mammalian hormone that seems involved in the lactation process and may be implicated in the control of involution. As a first step in investigating this hypothesis, the change in STC-1 levels in milk and serum was measured during drying off.

Serum levels of stanniocalcin-1 in Holstein heifers and cows.

Stanniocalcin-1 is a hormone that possesses both paracrine and endocrine functions and has recently been identified in mammals. While paracrine functions have been determined for several organs, the role of circulating stanniocalcin-1 in cattle is still unclear but, observations in mice and cows suggest that stanniocalcin-1 plays a role in both gestation and lactation. The changes in serum stanniocalcin-1 content in different physiological states have never been evaluated in ruminants.

Detection limits of several commercial reverse transcriptase enzymes: impact on the low- and high-abundance transcript levels assessed by quantitative RT-PCR.

Background: In functional genomics, transcript measurement is of fundamental importance. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays are the most popular technology and depend on the initial molecular step, the reverse transcription (RT). This study provides a complex overview of the influence of elements such as RT systems, amount of background RNA, and transcript abundance on the efficiency of qRT-PCR.

Effect of stage of lactation and parity on mammary gland cell renewal.

Milk production is a function of the number and activity of mammary epithelial cells, regardless of stage of lactation. Milk yield is generally higher in multiparous cows than in primiparous cows, but persistency is usually greater in the latter group. We compared several measures related to metabolic activity, apoptosis, and endocrine control of mammary cell growth in 8 primiparous and 9 multiparous cows throughout lactation.