Hadi Dashti; Ahmad Riasi; Mohammad Ali Edris; Golam-Reza Gohrbani; Hossein Omidi-Mirzaei
Abstract
The aim of this study was to consider reproductive performance parameters and blood progesterone concentration changes in high-producing dairy cows (39±2 kg per day) after artificial insemination, in summer and winter. 270 heads of Holstein dairy cattle were choose in three big dairy farms, and ...
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The aim of this study was to consider reproductive performance parameters and blood progesterone concentration changes in high-producing dairy cows (39±2 kg per day) after artificial insemination, in summer and winter. 270 heads of Holstein dairy cattle were choose in three big dairy farms, and blood samples were collected at days seven, ten and fourteen after artificial insemination. Temperature-humidity index was calculated according to one proposed formula (Dikmen and Hansen, 2009). The results showed that the maximum temperature–humidity index(THI) was 77.35 and 57.47 in summer and winter respectively. Pregnancy rates in cows inseminated during the winter months was significantly higher (p<0.01) than cows inseminated during the summer, and the effects of lactation on conception rate was significant in both seasons (p<0.01). Open days (101.18 vs. 165.07) and number of services per conception (2.05 vs. 3/48) in the winter were significantly lower than cows inseminated during the summer (p<0.01). In day 14 after insemination, blood serum progesterone concentration in cows inseminated in the winter was significantly higher (p<0.01) than summer. Results of this study showed that summer heat stress has significantly affects reproductive performance of dairy cows in central of Iran.
fatemeh amini; hamid amanloo; mohammad javad zamiri; najme eslamian
Abstract
To evaluate the effects of different dry period lengths on milk yield, milk composition, reproductive performance and energy balance in dairy cows, 30 Holstein breeds (average 270 days pregnant) were made use of in a randomized complete block design. Cows were assigned to three treatments (60, 45 and ...
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To evaluate the effects of different dry period lengths on milk yield, milk composition, reproductive performance and energy balance in dairy cows, 30 Holstein breeds (average 270 days pregnant) were made use of in a randomized complete block design. Cows were assigned to three treatments (60, 45 and 30 days of dry period) and two blocks as based on parity (either first lactation or multifarious cows). Milk production and composition as well as somatic cell counts of cows with 45 and 30 days of dry period were not significantly different from cows with 60 days of dry period (P>0.05). Body condition score changes after calving for 60, 45 and 30 days of dry period (1.06, 0.93 and 0.68, respectively) were significantly different. The smallest change in body condition score was observed for 30-day dry period ones, which also had a lower blood concentration of non-esterified fatty acids before calving (364.8 vs 394.9 and 390.9 µEq/l for 45- and 60-day dry periods). Mean days to first postpartum ovulation were 27.9, 27.8 and 22.7 days for dry periods of 60, 45 and 30 days, respectively (P
Mahmoud Vatankhah; Mehrab Faraji
Volume 42, Issue 4 , March 2012, , Pages 285-296
Abstract
Four hundered and ninety five (495) smallholder dairy farms active in 52 villages of different cities in Chaharmohalo Bakhtiari Province, keeping 1321 lactating within a total of 2811 mature cows (lactating and dry) were used. These herds were taken during winter 2009 to summer 2010 to assess some of ...
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Four hundered and ninety five (495) smallholder dairy farms active in 52 villages of different cities in Chaharmohalo Bakhtiari Province, keeping 1321 lactating within a total of 2811 mature cows (lactating and dry) were used. These herds were taken during winter 2009 to summer 2010 to assess some of the production, reproductive and economic performance traits under smallholder management system. A questionnaire survey was applied to collect retrospective data from the previous year's information, recorded information, direct recordings during the visit of the farms and as well interview with the smallholder farmer. The smallholder dairy farms included 441 small farms (89.09%), and 54 medium size farms (10.91%). From a breed aspect, there were: 11 native breed farms (2.22%), 327 cross bred farms (66.06%), and 157 Holstein breed ones (31.72%). The production performance figures were recorded as 30.56, 22.21 and 13.30 kg for total milk yield on farm, milk sold on farm and daily milk production per cow, respectively. A 62.75% of milk was reported as sold per total milk produced. The overall mean reproductive figures were recorded as 30.07 months for age for the first calving, 15.77 months for calving interval, 335.96 days for average lactation length and 6.99% for calf mortality rate. The mean daily feed consumption per cow was recorded as 15.85 kg, containing 25.69% of concentrate. The mean daily feed expenses and return from sale of milk were 35786 and 45765 rails, respectively. The ratio of feed expenses to income from milk and price of milk to feed ratio were found as 75.76% and 159%, respectively. The average herd size was 5.86 heads, including 2.21 lactating cows, and 2.67 total mature cows while the rest male and female calves. Also, the proportion of lactating cows to total cows and to total herd were estimated as 84.83% and 42.66% respectively. There were significant variations observed among different seasons, city and breed for most of the traits.
