Evaluation of two different oestrus-synchronisation methods with timed artificial insemination and resynchronisation of returns to oestrus in lactating Holstein cows.

To examine the outcomes of adding medroxyprogesterone acetate (MAP) to the ovsynch protocol with the traditional ovsynch protocol in both cycling and anoestrus cows, and to evaluate a resynchronisation protocol, 742 cows averaging more than 40 days postpartum were assigned to the following four treatments: (1) ovsynch (OVS): day 0: GnRH; day 7: PGF2alpha; day 9: a similar dose of GnRH; day 10: timed artificial insemination (TAI), approximately 16-20h later; (2) ovsynch+MAP (MAP): the same ovsynch protocol plus an intravaginal insert made of polyurethane sponge impregnated with 300mg of MAP immediately after the first GnRH treatment and on day 7, at the time of the PG treatment, the sponge was removed; (3) resynchronisation (MAP+ODB): 1mg of oestradiol benzoate (ODB) on day 13 after TAI and a new sponge impregnated with MAP was inserted and; on day 20, 1mg of ODB was given and the sponge removed; and (4) no resynchronisation (No MAP): only oestrus detection and AI at any repeat oestrus detected after TAI. Progesterone was measured in milk samples collected on days -17, -10, -3, 13 and 20 (TAI=day 0). Based on milk P4 at days -17 and -10, 27.4% of the cows were still anoestrus. At PG injection, 67.7% of the cycling and 21.3% of the anoestrus cows had elevated P4. Farm, days postpartum and parity variations were detected in both cases. On day 20 after TAI 42.6% of cycling and 8.3% of the anoestrous cows had elevated P4. Pregnancy rates were similar in both pre-breeding treatments (20%), but interactions (P<0.001) were detected between treatment and cycling activity (for anoestrous cows: MAP=34.9%; OVS=11.1%. Average interval from TAI to subsequent AI was 37+/-3 days. Resynchronisation resulted in more (P<0.001) cows in oestrus between days 18 and 25 after TAI. Conception rate in the MAP+ODB treatment was lower (P<0.05) than the No MAP group (22.8% versus 47.4%). It was concluded that the addition of a progestin to the ovsynch protocol resulted in increased pregnancy rates of cows treated during anoestrus. The benefit of including MAP with the ovsynch protocol for cycling cows is equivocal.

Fluid administration in the association of patent ductus arteriosus complicating respiratory distress syndrome.

Daily weights and mean daily fluid volumes administered to 62 infants with birth weights of less than 2,000 gm, who required respiratory support for respiratory distress syndrome, were reviewed. In 31 infants signs of patent ductus arteriosus developed. In a comparison group of 31 infants, the mean daily fluid volume was 144 ml/kg/24 hours, and the mean body weight was 102% of expected, differing significantly from the 189 nl/kg/24 hours, and 114% of expected weight in those infants who developed PDA. Those infants who developed PDA had not differed significantly from the comparison group in either mean daily fluid volumes or expected weights prior to a period two days before clinical evidence of PDA. Seven infants developed PDA in association with increased fluid administration on more than one occasion during nursery stay. Diuresis after excessive fluid administration was associated with improvement in, or resolution of, signs of PDA in many infants. The results suggest that excessive fluid administration to premature infants with RDS may be one factor associated with the developed of PDA complicating RDS (PDA/RDS).