McLean K A, Lawrence A B, Petherick J C, Deans L, Chirnside J, Vaughan A, Nielsen B L, Webb R
Genetics and Behavioural Sciences Department, SAC Edinburgh, UK.
Anim Reprod Sci. 1998 Feb 27;50(1-2):95-109. doi: 10.1016/s0378-4320(97)00088-2.
Maternal oestrogen and progesterone have been shown to be important in the initiation of maternal behaviour. Thirty-three Large White x Landrace gilts, housed in groups during pregnancy, were observed and aggressive interactions recorded. Individuals had jugular catheters implanted 14.5 (s.e. 0.34) days before their expected parturition date (EPD). Five days before EPD gilts were randomly allocated and moved to either a conventional farrowing crate (C; without straw, 16 gilts) or a pen (P; 2.1 x 3.1 m2; with straw bedding, 17 gilts). Blood samples were taken at frequencies determined by the proximity to farrowing onset. Piglets were removed at birth and returned 2 h after placental expulsion. The reaction of each gilt to her piglets was monitored. Gilts savaging piglets were sedated with azaperone (n = 8). There was no overall effect of farrowing environment on oestradiol and progesterone concentrations. The pre-farrowing ratio of progesterone to oestradiol was higher for (P) gilts (0.45 vs. 0.25, (P) vs. (C); S.E.D. 0.085, P < 0.05) as was their overall maximum oestradiol level (3.39 vs. 2.29 ng/ml, (P) vs. (C); S.E.D. 0.39, P < 0.01). In contrast to progesterone, oestradiol patterns varied considerably between individuals. Dominance rank value during pregnancy, but not levels of aggression, correlated positively to pre-farrowing oestradiol concentrations. Treatment with azaperone was not related to farrowing environment, piglet weight or litter size. Azaperone treated gilts showed a higher pre-farrowing oestradiol to progesterone ratio (0.55 vs. 0.29, +/- azaperone; S.E.D. 0.10, P < 0.05), significantly higher levels of oestradiol post-partum (0.7 vs. 0.19 ng/ml, +/- azaperone; S.E.D. 0.20, P < 0.001) and significantly lower levels of aggression during pregnancy (1.68 vs. 2.23 aggressive interactions/h, +/- azaperone; S.E.D. 0.15, P < 0.001). The results indicate that there are no major effects of farrowing environment on sex steroid concentrations. Maternal aggression under these conditions appears to be negatively related to aggression during pregnancy, but this is not reflected in plasma concentrations of sex steroids around parturition.
已证明母体雌激素和孕酮在母性行为的启动中起重要作用。33头大白猪与长白猪杂交的妊娠母猪，在孕期成群饲养，对其进行观察并记录攻击性行为。在预计分娩日期（EPD）前14.5（标准误0.34）天给个体植入颈静脉导管。在EPD前5天，将母猪随机分配并转移到传统产仔箱（C组；无垫草，16头母猪）或围栏（P组；2.1×3.1平方米；有垫草，17头母猪）。根据接近分娩开始的程度确定采血频率。仔猪出生时被抱走，胎盘排出后2小时再放回。监测每头母猪对其仔猪的反应。对咬仔猪的母猪用阿扎哌隆镇静（n = 8）。分娩环境对雌二醇和孕酮浓度无总体影响。P组母猪分娩前孕酮与雌二醇的比值更高（0.45对0.25，P组对C组；标准误差异0.085，P < 0.05），其总体最大雌二醇水平也更高（3.39对2.29 ng/ml，P组对C组；标准误差异0.39，P < 0.01）。与孕酮不同，个体间雌二醇模式差异很大。孕期的优势等级值与分娩前雌二醇浓度呈正相关，但攻击水平与雌二醇浓度无关。阿扎哌隆处理与分娩环境、仔猪体重或产仔数无关。用阿扎哌隆处理的母猪分娩前雌二醇与孕酮的比值更高（0.55对0.29，±阿扎哌隆；标准误差异0.10，P < 0.05），产后雌二醇水平显著更高（0.7对0.19 ng/ml，±阿扎哌隆；标准误差异0.20，P < 0.001），孕期攻击水平显著更低（1.68对2.23次攻击互动/小时，±阿扎哌隆；标准误差异0.15，P < 0.001）。结果表明，分娩环境对性类固醇浓度无主要影响。在这些条件下，母体攻击行为似乎与孕期攻击行为呈负相关，但这在分娩前后的性类固醇血浆浓度中未体现出来。
