Farm management and economic factors associated with bulk tank total bacterial count in Holstein dairy herds in Iran.

The objectives of this research were (1) to study different factors affecting milk total bacterial count (TBC) and (2) to estimate the economic value associated with TBC in Holstein dairy herds in Iran. The relationships between bulk tank TBC and farm management and economic factors were examined on 56 randomly selected intensive dairy farms. Herd management factors associated with bulk tank TBC were determined using mixed linear models. The median bulk tank TBC for the sample herds was 299 (range 81-1185) × 103 cfu/ml. The average economic premium opportunity from bulk tank TBC was US$ 1.32 per ton of milk ranging from US$ 0.02 per ton of milk for herds applying wet tissue procedures as teat cleaning material and washing the water troughs three times per day to US$ 5.20 per ton of milk for herds with dirty barns. Results showed that the following management factors were associated with low TBC and high economic value: frequency of cleaning water troughs, teat cleaning material, the frequency of milk delivery to the processor, bedding material, herd size, education level of workers, udder washing material, material of milking parlor wall, frequency of disinfection of the calving area, presence of veterinarian, water quality control, having a hospital pen and barn hygiene. In conclusion, our findings highlight the need to pay more attention to farm management issues, particularly farm hygiene practices to reduce milk TBC and so reduce the economic burden of TBC in dairy herds in Iran.

Assessing the consequences and economic impact of retained placenta in Holstein dairy cattle.

Retained placenta (RP) is as an important reproductive disorder which adversely affects the economic performance of dairy cows. Understanding the consequences and economic losses associated with RP can persuade dairy farmers to consider it more effectively in their management decisions. Hence, the aims of this research were to assess the effect of RP on production and reproduction attributes as well as economic losses in Iranian Holstein cows. The data was collected from nine Holstein dairy herds in Isfahan province of Iran. The final dataset comprised of 139,508 records of 58,086 cows which calved between March 2011 and December 2018. A linear mixed model was developed to evaluate the effect of RP on individual performance of primiparous and multiparous cows. The economic losses associated with the RP were finally estimated. The average incidence of RP per cow over a year was 12.3% (ranged between 9.0 and 15.4%). Each incidence of RP significantly reduced milk, fat and protein yields in primiparous and multiparous cows (P < 0.05). The adverse effect of RP on the milk production was much higher in the cows at the early phase of lactation (i.e. 100-d lactation group) than the cows in mid or late lactation. The estimated production losses (±standard deviation) due to the RP event were 282.1 ± 43.0 and 295.7 ± 40.8 kg per cow for a 305-d lactation period in primiparous and multiparous cows, respectively. However, the fertility performance was less affected by the RP in primiparous compared to multiparous cows. The average of days open increased by 8.3 ± 5.3 and 19.8 ± 7.1 d in primiparous and multiparous cows, respectively. The financial losses associated with RP were on average US$ 350.4 and US$ 481.2 per incidence in primiparous and multiparous cows, respectively, ranged from US$ 311.9 to 456.2 depending on the parity number (primi- or multiparous) and herd management. The highest financial losses due to RP were associated with reduction in milk production (38.5% of total loss) and low fertility (28.5% of total loss) had the highest contribution in in primiparous and multiparous cows, respectively. The results of our research highlight the economic importance of improved calving management to reduce RP occurrence in dairy cows.

Economic evaluation of sexed semen use in Iranian dairy farms according to field data.

In this study, at first, the reproductive consequences of sexed semen use were quantified and then the cost-benefit of sexed semen use on Iranian commercial dairy farms was evaluated. Retrospective data collected during 2006 to 2013 from four large dairy farms in the Isfahan province of Iran were used for this study. These data included of 13,003 heifers records, from which 11.2% used sexed semen from 33 different bulls. All data were analysed using a multivariable logistical regression model, GENMOD procedure from SAS software. The analyses included economic values (EVs) when sexed semen was used in 1, 2 and 3 consecutive services compared with conventional semen use for all insemination. Results showed that rates of female born from sexed semen (86.3%) were 1.8 times higher than those from conventional semen (48.5%). Conception rates were 43.8% for sexed and 59.2% for conventional semen (p < 0.0001). Abortion (4.4% vs. 5.4%) and stillbirth (8.4% vs. 7.2%) rates were not significantly different between sexed and conventional semen (p = 0.09). Dystocia rates were 15.5% for sexed and 19.6% for conventional semen (p = 0.002). Sexed semen use showed negative EVs through all investigated scenarios. The EVs from the implementation of 1, 2 and 3 sexed semen breedings were estimated to be $-6.69, $-14.01 and $-19.08, respectively. Total insemination cost and increased cost of age at first calving were the most important components associated with negative EV for sexed semen. Sensitivity analysis showed that proportion of conception rates of sexed semen to conventional semen and female calf value were the most important biological and economic factors influencing on the EV of sexed semen, respectively. Breakeven would be obtained with 77.4%-79.3% conception rates or female calf value of $719.5-$754.7 through investigated breeding scenarios when all other factors remained the same.