Figure 1.
Figure 1.

Experiment 1: On d 0 and 28 of the experiment (i.e., ≈ 42 d and ≈ 14 d prepartum, respectively), ewes (n = 10/group) received a subcutaneous injection of either a control (open squares; 1 mL of adjuvant + 1 mL of sterile isotonic saline) or ovalbumin preparation (open circles; 12 mg of ovalbumin + 1 mL of aluminum hydroxide gel adjuvant + 1 mL of sterile isotonic saline). Ewes lambed 45 ± 5 d (vertical dashed line) after d 0 of the experiment. Antiovalbumin IgG (OV-IgG) was measured in weekly serum samples from jugular blood. Serum from each sample was diluted 1:100 in PBS; 100 μL of diluted sample was assayed; and data were expressed as optical density units (odu). Ovalbumin injections increased (P < 0.001) serum OV-IgG, and serum OV-IgG changed with time after the first injection (ovalbumin treatment × day interaction, P < 0.001). Values are least-squares means, with a pooled SE of 0.007 odu.

 


Figure 2.
Figure 2.

Experiment 1: Lambs (n = 66) were from ewes (n = 10/group) that had received either control (open squares) or ovalbumin (open circles) injections before lambing. Beginning the day after lambing, jugular blood was collected weekly from each lamb for antiovalbumin IgG (OV-IgG) quantification. Serum from each sample was diluted 1:100 in PBS; 100 μL of diluted sample was assayed; and data were expressed as optical density units (odu). Throughout the sampling period, serum OV-IgG was greater (P < 0.0001) in lambs from ovalbumin-treated ewes than it was in lambs from control ewes. Values are least-squares means, with a pooled SE of 0.024 odu.

 


Figure 3.
Figure 3.

Experiment 2: Lambs were from ewes (n = 40) that had been inoculated against ovalbumin during the last 6 wk of pregnancy. On d 1 and 15 of age, lambs (n = 20/group) received a subcutaneous injection of either a control (open squares; 1 mL of adjuvant + 1 mL of sterile isotonic saline) or ovalbumin preparation (open circles; 12 mg of ovalbumin + 1 mL of aluminum hydroxide gel adjuvant + 1 mL of sterile isotonic saline). Jugular blood was collected just before each injection and at weekly intervals until the lambs were approximately 36 d of age, and antiovalbumin IgG (OV-IgG) was quantified. Serum from each sample was diluted 1:100 in PBS; 100 μL of diluted sample was assayed; and data were expressed as optical density units (odu). Ovalbumin treatment did not affect mean serum OV-IgG, but the treatment × age interaction was significant (P < 0.0001). Antiovalbumin IgG was less (P < 0.04) in ovalbumin-treated than in control lambs from d 1 to d 15. After d 15, OV-IgG was greater (P < 0.001) in ovalbumin-treated than in control lambs. Values are least-squares means, with a pooled SE of 0.009 odu.

 


Figure 4.
Figure 4.

Experiment 3: Lambs (n = 20/group) were from ewes that had not been inoculated with ovalbumin. The following treatments were assigned to lambs soon after birth: 1) control injection (open squares, solid line; 1 mL of adjuvant + 1 mL of sterile isotonic saline) on d 1 of age + control injection on d 15 of age; 2) ovalbumin injection (open circles, solid line; 12 mg of ovalbumin + 1 mL of aluminum hydroxide gel adjuvant + 1 mL of sterile isotonic saline) on d 1 + ovalbumin injection on d 15; 3) control injection (closed squares, dotted line) on d 28 + control injection on d 42; and 4) ovalbumin injection (closed circles, dotted line) on d 28 + ovalbumin injection on d 42. All injections were subcutaneous. Jugular blood samples were collected before the injections and at weekly intervals for 5 wk for antiovalbumin IgG (OV-IgG) quantification. Serum from each sample was diluted 1:100 in PBS; 100 μL of diluted sample was assayed; and data were expressed as optical density units (odu). Injection type (control vs. ovalbumin; P < 0.0001), but not injection schedule (d 1 and d 15 vs. d 28 and d 42 of age; P = 0.59), affected OV-IgG. The injection type × injection schedule interaction was not significant (P = 0.84). Time after injection affected (P < 0.0001) OV-IgG, and the injection type × time and injection schedule × time interactions were significant (P < 0.0001). The injection type × injection schedule × time interaction was not significant (P = 0.34). Values are least-squares means, with a pooled SE of 0.01 odu.

 


Figure 5.
Figure 5.

Experiment 3: Lambs (n = 20/group), which were from ewes that were naïve to ovalbumin, had received one of the following treatments: 1) control injection (open squares, solid line; 1 mL of adjuvant + 1 mL of sterile isotonic saline) on d 1 of age + control injection on d 15 of age; 2) ovalbumin injection (open circles, solid line; 12 mg of ovalbumin + 1 mL of aluminum hydroxide gel adjuvant + 1 mL of sterile isotonic saline) on d 1 + ovalbumin injection on d 15; 3) control injection (closed squares, dotted line) on d 28 + control injection on d 42; and 4) ovalbumin injection (closed circles, dotted line) on d 28 + ovalbumin injection on d 42. Also, at an average age of 159 d, which was soon after weaning, lambs received either a control or an ovalbumin injection that was consistent with their original injection type. All injections were subcutaneous. Jugular blood samples were collected immediately before the d-159 injections and at weekly intervals for the next 4 wk to quantify antiovalbumin IgG (OV-IgG). Serum from each sample was diluted 1:100 in PBS; 100 μL of diluted sample was assayed; and data were expressed as optical density units (odu). Injection type (control vs. ovalbumin; P < 0.0001), but not initial injection schedule (d 1 and d 15 vs. d 28 and d 42 of age; P = 0.59), affected OV-IgG. The injection type × injection schedule interaction was not significant (P = 0.08). Time after injection (P < 0.0001) affected OV-IgG, and the injection type × time interaction was significant (P < 0.0001). Injection schedule × time and injection type × injection schedule × time were not significant (P = 0.86 and 0.68, respectively). Values are least-squares means, with a pooled SE of 0.013 odu.