Impact of concurrent pregnancy and lactation on maternal nestbuilding, estradiol and progesterone concentrations in rabbits

Abstract

We evaluated the impact of concurrent pregnancy and lactation on: nest-building (i.e., digging, straw-carrying, hair-pulling), food intake, milk output, body weight, and the concentration of estradiol and progesterone in blood. Digging was lower in pregnant-lactating (PL) rabbits, compared with pregnant-only (PO) does, on 21-23 d (52±64 vs. 104±86 g, respectively; mean±SD; P<0.05). Straw-carrying was also reduced in PL does on 24-26 d (9±27 vs. 79±94 g; P<0.005), 27-29 (27±56 vs. 99±77 g; P<0.005), and in the total amount of material introduced into the nest box (132±167 vs. 286±217 g; P<0.02). Hair-pulling was expressed by practically all animals. Food intake declined in PO does on the three days preceding parturition (P<0.01) and increased markedly during lactation; this increase was much larger in PL than in lactating-only (LO) rabbits (P<0.01). Milk output was similar between PL and LO does during the fi rst 21 d of lactation but a marked decline in this parameter occurred in PL does from then until 30 d. The differences in nest-building between PL and PO rabbits may be related to the concentrations of estradiol and progesterone on specifi c days of pregnancy. PL does showed signifi cantly higher estradiol levels than PO animals on pregnancy 1 d (33±13 vs. 23±4 pg/mL; P<0.02) and 21 (34±19 vs. 24±6 pg/mL; P<0.05) and also higher levels of progesterone on pregnancy 1 d (4±5 vs. 1±2 ng/mL; P<0.05). However, PL rabbits had lower levels of progesterone on 7 d (6±3 vs. 9±2 ng/mL; P<0.02) and 14 d (8±3 vs. 11±3 ng/mL; P<0.005) than PO does. Our results indicate that the unique endocrine milieu of PL rabbits has a direct bearing on specifi c behavioral and physiological phenomena that impact productivity on the farm.

Litter Size Determines Circadian Periodicity of Nursing in Rabbits

“…Available evidence-obtained in male rats (Arletti et al, 1990), male mice (Rinaman et al, 2005), and adult nonlactating female goats (Meyer et al, 1989)-indicates that OT and AVP reduce food and fluid intake. Yet, lactating rabbits consume much more feed (González-Mariscal et al, 2009) and water (Denton & Nelson, 1971;Szendrö et al, 1999) than do estrous does, and, in the latter, there is a linear relationship between food and water intake (Cizek, 1961). Whether OT or AVP are responsible for the perinursing display of drinking and eating bouts remains to be determined, as, to our knowledge, the effects of such peptides on food and water intake have not been tested in lactating animals.…”

Hormonal regulation of pregnancy and related behavioral changes in rabbits

“…In case of co-existing pregnancy and lactation the doe's body needs to adjust the hormonal profile so that the pregnancy is sustained and there is sufficient food for the young ones (57). González-Mariscal et al (42) conducted a study on a group of lactating pregnant females and a group of lactating non-pregnant females. The estradiol concentration was comparable in both experimental groups throughout the study period.…”

Characteristics of suckling stimulation determine the daily duration of mother‐young contact and milk output in rabbits

“…Yet, across lactation the condition of the mammary gland changes (Neville, 2006), the amount of milk produced increases and then decreases (González-Mariscal et al, 1994;González-Mariscal, Gallegos, Sierra-Ramírez, & Garza Flores, 2009;Lebas, 1987;Partridge, Lobley & Fordyce, 1986), the components of milk vary (Cowie, 1969;Jensen, 1995), and the secretion of prolactin in response to suckling decreases in late lactation (Fuchs, Cubile, Dawood, & Jørgensen, 1984). Thus, we hypothesized that the relative importance of nipple stimulation for determining maternal TINB would change across lactation.…”