000			03200nab a2200325 a 4500
003			AR-ReUNN
005			20260702002302.0
008			260630s2007 ag |||||||||||||||||spa
041	0		_aspa _aeng
100	1		_aTuñon, G. _9125738
700	1		_aParkinson, T. J. _9125739
700	1		_aHolmes, C. W. _9125740
700	1		_aChagas, L. M. _9125741
245	1	0	_aEffect of premating supplementation with monopropylene glycolon reproductive performance of dairy cows / G. Tuñon ... [et al.]
264		1	_c2007
300			_a9 páginas
520			_aAbstract : Prolonged postpartum anoestrous intervals (PPAI) are the major source of infertility in New Zealand dairy cows. Postpartum supplementation with monopropylene glycol (MPG), under controlled experimental conditions, was previously shown to reduce PPAI in heifers. This experiment tested this treatment in four large commercial dairy herds. During the 6-week period preceding the planned start of mating (PSM, week 0), cows were drenched either once (MPGx1) or twice (MPGx2) daily with 200 ml MPG, or served as untreated controls. A total of 2,122 cows were included in the analysis (n = 684 to 714 per treatment). None of the four variables: oestrous behaviour during the treatment period, anoestrous rate one week before PSM, 3-week submission rate, or 3-week pregnancy rate were affected by MPG. However, MPG did increase the 6-week and final pregnancy rates (p<0.005), with MPGx1 having higher values (74.6% and 92.1%) than MPGx2 (69.1% and 88.5%) and control (67.7% and 88.1%), respectively. MPG cows also produced more milk protein than the control cows, by 0.01 and 0.017 kg of milk protein per day for MPGx1 and MPGx2, respectively (p=0.02), evidence of a metabolic effect of MPG. Recent studies suggest that diets that are optimal for follicle growth are not necessarily optimal for oocyte quality and subsequent embryo survival. It is hypothesised that MPGx1 had positive effects on the follicle/oocyte through gonadotrophin-independent mechanisms and that MPGx2 had negative effects on the embryo. Probably the gonadotrophin-dependent effects necessary for ovulation could not be exerted in the present study because MPG was not administered for sufficient time to effect the LH surge. Both change in body condition score (BCS) between week -6 and week -1, and proportion of cows that were anoestrus at week -1, were influenced by herd, age and time of calving (p<0.05) but not by treatment (p>0.1). Change in BCS affected both milk yield and pregnancy rates, with cows that gained BCS producing less milk (p=0.01) but showing higher 6-week pregnancy rates (p<0.05). This study highlighted that key factors influencing the percentage of anoestrus at PSM are cow age, time of calving and management of the herd.
650		4	_aReproducción Animal _9116257
650		4	_aVaca _9115966
650		4	_aLeche _923303
650		4	_aCondición Corporal _9123388
650		4	_aPreñez _9123374
650		4	_aAnestro _9118175
650		4	_aTambo _920183
650		4	_aMonopropilenglicol _9125742
773	0		_tRevista Veterinaria _x1668-4834 _gv. 17 n. 1 (2006) _w217547
942			_cART
035			_a(AGROP)41004
001			217673
999			_c217673 _d217673
040			_aAR-ReUNN _bspa _cAR-ReUNN _eaacr2