Since the initial report in 1978 of galactopoietic effects of a photoperiod of 16 h of light:8 h of darkness, numerous studies have confirmed long-day stimulation of milk yield. The endocrine factor(s) responsible for increased milk yield, however, has eluded identification. Recent studies suggest that insulin-like growth factor-I (IGF-I) may mediate the galactopoietic response to long day phot...

In this study test-day records of milk (kg), fat (g), and protein (g) yields, somatic cell score (SCS, cells/ML) collected by Animal Breeding Center of Iran during 2007 and 2009 were used to estimate genetic parameters using random regression model. Models with different order of Legendre polynomials were compared using Bayesian information criterion (BIC).For milk, fat yield and SCS genetic an...

The effects of an intraruminal load of 3 litres of water on body water movements was compared in Sardi sheep during the last month of pregnancy, lactation and a non-pregnant, non-lactating control period. Before the water load, rumen fluid volume, estimated by polyethylene glycol was similar in pregnant, compared to control, animals and 27% higher in lactating sheep. After the water load, rumen...

Raising dairy heifers from birth to calving has been found to comprise the second largest expense on the dairy farm towards the production of milk, while deriving no revenue until the onset of lactation (Heinrichs, 1993). Therefore, many experiments involving dairy heifers have focused on ways to minimize the costs associated with the growth period or decreasing the unproductive period of the a...

2) sows receiving 1 g/kg of MOS during lactation, and dietary treatment: 1) basal diet (control), and 2) basal diet with MOS at 2 g/kg in prestarter and 1 g/kg in starter diets. The experimental design was applied in both the prestarter (28 to 44 d of age) and the starter (44 to 60 d of age) periods. Nutritive value of the diets was 2.5 Mcal NE/kg and 14.8 g/kg lysine for prestarter, and 2.5 Mc...

BACKGROUND: Dairy cows undergo physiological changes during pregnancy and lactation and cardiovascular system may alter during these periods. OBJECTIVES: Understanding the physiological effects of production periods of dairy cows on heart electrical activities can aid to better monitoring the cardiovascular system in these animals. METHODS: Five multiparous Holstein dairy cows were studied from...

Knowledge related to udder health in dairy practice is considerably limited. The aim of the experiment was to study the changes of somatic cell counts (SCC) in milk in relation to the month of year, stage of lactation and parity under the practical conditions. Also the frequency of incidence of high SCC during the year was observed. The effectiveness of dry therapy and calving process on SCC wa...

in this study test-day records of milk (kg), fat (g), and protein (g) yields, somatic cell score (scs, cells/ml) collected by animal breeding center of iran during 2007 and 2009 were used to estimate genetic parameters using random regression model. models with different order of legendre polynomials were compared using bayesian information criterion (bic).for milk, fat yield and scs genetic an...

First lactation records (174) of Jersey×Sahiwal and Holstein Friesian×Sahiwal half breds under 9 sires maintained at Chandra Shekher Azad University of Agriculture and Technology, Kanpur, Uttar Pradesh, India from 1975-1983, were used to estimate the genetic parameters and to predict herd life milk yield and average milk yield per day of herd life from first lactation traits. The traits include...

The effects of melatonin administration and pinealectomy on the milk ejection response were studied in the rat. The amounts of milk obtained by a litter during 1 hr suckling and during an additional 30 min suckling after 1 I.U. of oxytocin injection, following 7 or 8 hr separation from the mother on the 10th or 16th day of lactation, were considered as the naturally ejected milk and the residua...