The objective of work was to evaluate effects of milk production level (MY1≥9500 kg, n=23; MY2 = 8000-9499, n=28; and MY3≤7999 kg, n=29) and calving interval length (CI1≥440 days, n=22; CI2 = 400-439 days, n=33; and CI3≤399 days, n=25) on the lactation curve parameters calculated using MilkBot® Model and economic profitability of Holstein dairy cow breeding. Data were obtained from 80 Holstein cows on 1st to 4th parity calved between January and August 2012 on the dairy farm of the Czech University of Life Sciences Prague in Czech Republic. Lactation curve parameters differed more in relation with milk production level compared to calving interval length. Lactation curve in cows with the highest MY was characterized with significantly higher overall magnitude (scale parameter) of milk production (P<0.01), higher peak yield (P<0.01) which occurred later (P<0.05) and higher persistence (P<0.05). Due to combination of higher persistence and total yield, average milk yield per day of calving interval was significantly (P<0.05) higher in cows with middle CI than in short CI. Optimal calving interval length should be assessed in relation with lactation persistence and milk production level. The highest individual profitability was reached by cows in MY1 and CI2 group.

DOLEŽALOVÁ MARTINA, STÁDNÍK LUDĚK, NEJDLOVÁ MICHAELA, NĚMEČKOVÁ DANA, BERAN JAN, DUCHÁČEK JAROMÍR: The relationship between energy balance a er calving and reproductive functions in Holstein dairy cows treated by the OVSYNCH system. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2013, LXI, No. 3, pp. 601-610 The objective of this research was to evaluate the relationship between the course and the depth of negative energy balance (NEB) rated by changes of the body condition a er calving and subsequent recovery of reproductive abilities of Holstein dairy cows treated by OVSYNCH. The body condition was evaluated by the BCS system one week before calving and subsequently at 30-day intervals for the period of 6 months of lactation. Recovery of ovarian functions was evaluated by the results of ultrasound examination of all the dairy cows' ovaries in two controls a er calving. The fi rst one was performed on an average of 67 days a er calving, and the second at a 60-day interval. The occurrence of individual fi ndings -the presence of corpus luteum, ovarian cysts or ovaries without fi ndings was evaluated as an eff ect of NEB on the recovery of the ovarian cycle of dairy cows and their subsequent possibility of conception. The suitable cows were treated by the OVSYNCH system a er the 1 st and 2 nd ultrasound examination. Therefore, the insemination interval was calculated and in the case of dairy cows, pregnancy detection, also the number of services per conception and the length of open days. Twice performed hormonal treatment of 73.6% of the animals delayed the period by 50.2 days. In all, 202 dairy cows calved in the period from 29 th July 2011 to 7 th February 2012 were included in this observation. Signifi cant eff ects of the body condition change on the ovarian activity as documented by sonographic examination and reproductive indicators appeared primarily in the second month of lactation. The best reproductive indicators were found in cows with the lowest body condition change, thus with a small decline or even increase of body condition score (−0.0 to +0.75 points, P < 0.05). On the contrary, the worst level of indicators of recovery of the reproduction functions were documented in the dairy cows with the most marked decline of BCS (P < 0.05). dairy cattle, energy balance, body condition, ovarian functions, reproductionThe most common problem in dairy cows is health and fertility (Garnsworthy, 1988). Milk yield in dairy cows increased through intensive breeding (Říha et al., 2003) as a result of one-sided selection; however, fertility and reproductive parameters simultaneously declined in most herds (Motyčka et al., 2005). The rapid increase of energy requirements a er calving are related to the start of lactation and result in a negative energy balance (Říha et al., 2000). The result of the NEB eff ect at the beginning of lactation is reduction of conception ability, which causes prolongation of the calving interval (Collard et al., 2000) and is related to deterioration o...

The monitoring was performed in one year period in selected population of Suffolk sheep (SF, n = 257) and their crossbreds with Merinolandschaf (SF × ML, n = 87). Total of 627 lambs (SF, n = 463; SF × ML, n = 164) were observed in breeding conditions of two semi-extensive flocks. Lambs' live weight at 100 days of age (LW100); musculus longissimus lumborum et thoracis (MLLT100) depth and backfat thickness (BT100) at the same age were assessed. Effects of breed, ewes' live weight at mating, litter size, sex of lambs and ewe's age as linear regression were evaluated using SAS 9.1. Significant differences (P < 0.05) in LW100, MLLT100 and BT100 between SF and SF × ML were observed. All the evaluated traits of growth performance were also influenced (P < 0.05) by ewes' live weight at mating. The highest lambs' growth performance traits were detected in lambs of ewes with highest live weight at mating (group of ≥ 80.7 kg). Significant differences (P < 0.05) were observed among singles, twins and triplets lambs as well. Significantly higher LW100 was marked in ram lambs compared to ewe lambs (P < 0.05).

The objective of this study was to compare microclimatic conditions in three different housing systems designed for calf rearing -individual wooden hutches, individual tarpaulin hutches and individual pens under shelter -and to evaluate the thermal comfort of calves reared in these systems. Air temperature, relative air humidity and the rectal temperature of calves (n=324) were measured in the hutches and pens during three consecutive years. The hypothesis that the climatic conditions of different housing system designs used in calf rearing affect the thermal comfort of calves was confirmed, as the design of the individual housing systems affected microclimatic conditions and subsequently the rectal temperature of the housed calves as well. Statistically significant differences (P<0.05) were found between the shelter and individual outdoor calf hutches in relation to the measured parameters. In the summer, the shelter showed a significantly (P<0.05) lower air temperature and significantly higher level of both relative air humidity and calf rectal temperature. These significantly higher rectal temperatures in both summer and in transitional periods (from March to June and from September to December) can be explained by microclimatic conditions and specifically by the combination of air temperature and the highest relative humidity that caused less comfortable microclimatic conditions for calves. The high relative humidity is probably caused by inadequate ventilation under the shelter. Therefore, new technology of calf housing under shelter could be recommended as suitable housing only if adequate ventilation is provided.

, where: SHME2 = lean meat percentage area of the belly 2 from total cut area, he2a = the belly2 height at point 1, ARTO2 = the belly2 total cut area, HE3A = the belly3 height at point 1. compared to lean meat, the percentage of belly fat (bf%) appears to be a more appropriate criterion for the objective evaluation of belly composition due to the simplicity and accuracy of the final regression equation (higher R 2 ).