Methods for evaluating and developing commercial chicken strains free of endogenous subgroup E avian leukosis virus

Figures & data

Table 1. Tumour induction by RSV(RAV-60) in lines 15B1, 0 and 0×1 F₁ chickens

		Experimental challenge number (number with tumours/total)^a
Line	Band number or number tested	1	2	3	Line totals (number with tumours/total)
15B1	I831A	0/1	Died	Not done
15B1	I835A	0/1	0/1	0/1
15B1	I831B	1/1	Not done	Not done
15B1	I816B	Not done	Not done	1/1
15B1	I834E	Not done	Not done	1/1
15B1	I818C	Not done	Not done	1/1
15B1	J836B	Not done	Not done	1/1
15B1	J814C	Not done	Not done	1/1
15B1	J830E	Not done	Not done	1/1
15B1	J826B	Not done	Not done	1/1
15B1	J831B	Not done	Not done	1/1	9/11
0	I925C	0/1	0/1	0/1
0	I929B	0/1	0/1	0/1
0	I938C	0/1	0/1	1	1/3
0×1 F1	28 chickens	0/28	0/28	0/28	0/28
^a Each adult chicken received RSV(RAV-60) in the wing web (approximately 38 FFU in experiments 1 and 2 and 380 FFU in experiment 3). The presence of tumours was observed at 10, 14 and 17 days post-inoculation.

Table 2. Use of 0×1 F₁ chickens to test RSV resistance and to produce F₂ chickens

		F1×72 chickens (number of tumours/total)^c		Production of 0×1 F2 chickens^d			B*21/*21, ALVE 0
Line 1 hen code^a	F1 breeder (sex, chicken)^b	RSV-A	RSV-B	F1 male breeder number	F1 hen breeder number	Total chicks	Number of males	Number of hens
A	M, # {\rm \underline{9}}	18/18	{\rm \underline{5/}} {\rm \underline{13}}
B	M, #8	14/14	14/14
C	M, #7	11/11	11/11
D	M, #6	11/11	11/11
E	M, #5	10/10	10/10
F	M, #4	13/13	13/13
G	M, #3	12/12	12/12
H	M, #2	11/11	11/11
I	M, #1	14/14	14/14
A	F, #1	11/11	11/11	1	1	26	0	3
A	F, # {\rm \underline{2}}	11/11	{\rm \underline{5/}} {\rm \underline{11}}	1	2	26	Discard	Discard
A	F, #3	11/11	11/11	1	3	27	0	0
A	F, # {\rm \underline{4}}	12/12	{\rm \underline{7/}} {\rm \underline{12}}	2	4	21	Discard	Discard
A	F, # {\rm \underline{5}}	12/12	{\rm \underline{7/}} {\rm \underline{12}}	2	5	27	Discard	Discard
A	F, #6	11/11	11/11	2	6	28	2*	0
A	F, #7	14/14	13/14	2	7	22	0	0
A	F, # {\rm \underline{8}}	14/14	{\rm \underline{9/}} {\rm \underline{14}}	2	8	28	Discard	Discard
A	F, # {\rm \underline{9}}	10/10	{\rm \underline{5/}} {\rm \underline{10}}	3	9	24	Discard	Discard
B	F, #10	11/11	11/11	3	10	23	0	0
B	F, #11	11/11	11/11	3	11	23	0	1
B	F, #12	11/11	11/11	3	12	25	0	0
B	F, #13	11/11	11/11	4	13	29	0	2
C	F, #14	11/11	11/11	4	14	25	2	2
C	F, #15	11/11	11/11	4	15	25	3*	1
C	F, #16	11/11	11/11	4	16	28	1*	1
C	F, #17	11/11	11/11	4	17	27	0	0
D	F, #18	11/11	11/11	5	18	27	1	1
D	F, #19	7/7	7/7	5	19	25	2	0
D	F, #20	11/11	11/11	5	20	28	0	1
D	F, #21	11/11	10/11	5	21	29	1*	1
D	F, #22	11/11	10/11	5	22	26	2*	0
E	F, #23	11/11	11/11	6	23	26	1*	0
F	F, #24	11/11	11/11	6	24	24	1*	1
F	F, #25	11/11	11/11	6	25	26	0	1
G	F, #26	6/6	6/6	6	26	28	1	0
G	F, #27	3/3	3/3	7	27	24	0	1
G	F, #28	10/10	9/10	7	28	32	0	1
G	F, #29	7/7	7/7	7	29	22	1	0
G	F, #30	12/12	12/12	7	30	29	1*	0
G	F, #31	13/13	13/13	7	31	28	2*	1
H	F, #32	11/11	11/11	8	32	24	1	1
H	F, #33	12/12	12/12	8	33	23	2*	1
H	F, #34	8/8	8/8	8	34	27	1*	1
H	F, #35	13/13	12/13	8	35	25	0	0
H	F, #36	14/14	14/14	9	36	24	Discard	Discard
I	F, #37	12/12	12/12	9	37	29	Discard	Discard
I	F, #38	4/4	4/4	9	38	28	Discard	Discard
J	F, #39	11/11	11/11	9	39	26	Discard	Discard
J	F, #40	11/11	11/11	9	40	27	Discard	Discard
Total						1041	25	21
^a Each of the line 1 hens that produced 0×1 F1 offspring was assigned a letter (A to J, column 1), and F1 breeders from that hen are given in column 2.
^b Each F1 breeder was assigned a number (1 to 9 for males; 1 to 40 for females) as indicated.
^c Each F1 breeder was mated to line 72 to obtain approximately 10+ chicks. Each chick was challenged with subgroup A RSV(RAV-1) in the right wing web, and subgroup B RSV(RAV-2) in the left wing web. After approximately 10 and 14 days the presence of tumours was monitored and the number chicks with tumours/number of chicks injected is given for subgroup A (column 3) and subgroup B (column 4) RSV. The breeder number and tumour values are underlined when results indicate the breeder is heterozygous and segregating for genes determining resistance to subgroup B RSV(RAV-2).
^d 0×1 F2 chickens were produced by mating a F1 male to F1 females as indicated in columns 5 and 6. The total number of F2 chicks produced and analysed for B haplotype (by RBC agglutination) and for absence of ALVE genes (by Southern blot) is given in column 7. The number of males and females that were B*21/*21, and lacking ALVE is given in columns 8 and 9. One male from each F2 family marked with an * in column 8, and all the F2 females in column 9, were used to produce line 01 (generation 1) using non-sib matings. Note that F2 breeders were only used if both of their F1 parents were homozygous susceptible to subgroup A RSV(RAV-1) and subgroup B RSV(RAV-2).

Table 3. Comparison of susceptibility of CEF from ADOL lines 0×1 F₂, 0₁, 0, and15B1 to ALV A, ALV B, ALV C, ALV J and ALV E

		ALV^b
Embryo line^a	Mating	Subgroup A	Subgroup B	Subgroup C	Subgroup J	Subgroup E	None
0×1 F2	1	1.38	2.06	1.42	1.54	0.095	0.054
	2	2.06	2.12	1.58	1.58	0.074	0.049
	3	2.03	1.95	1.35	1.53	0.093	0.074
	4	1.88	2.13	1.44	1.54	0.094	0.6
	5	2.15	2.2	1.49	1.05	0.065	0.073
	6	1.45	2.14	1.37	1.31	0.053	0.094
	7	1.59	1.55	1.45	1.35	0.014	0.02
	8	1.59	1.44	1.46	1.28	0.01	0.018
Controls
0		1.94	1.83	1.53	1.46	0.075	0.027
15B1		1.9	1.9	0.29	1.48	1.278	0.059
01	1	1.36	1.43	1.32	1.51	0.029	0.015
	2	1.27	1.36	1.27	1.38	0.019	0.023
	3	1.33	1.32	1.27	1.26	0.019	0.006
	4	1.35	1.07	1.25	1.23	0.024	0.01
	5	1.31	1.31	1.2	1.21	0.018	0.018
	6	1.32	1.32	1.16	1.21	0.026	0.009
Controls
0		1.33	1.31	1.28	1.31	0.033	0.019
15B1		1.35	1.34	0.154	1.34	0.638	0.08
^a Egg fertility was established by artificial insemination. Pooled semen was used in lines 15B1 and 0. 0×1 F2 embryos were from matings of eight individual males, and 01 embryos were from six individual males. Primary CEF were prepared from three embryos per mating, and 10 plates of CEF were frozen.
^b From each primary CEF preparation two plates of secondary CEF were infected with a prototype of each ALV; that is, RAV-1 (subgroup A), RAV-2 (subgroup B), RAV-49 (subgroup C), Hc1 (subgroup J), or EV 2 (subgroup E). ALV growth was based on detection of capsid P27 antigen in culture supernatants after 8 days using an ELISA. OD630 values were obtained from duplicate 24-well microtitre plates and a value>0.1 indicates the CEF are susceptible to the virus used.

Figure 1. Fertility and viability of line 0 eggs at 11 days incubation (2000/2001).

Table 4. Reproduction and egg characteristics of line 0, 0×1 F₁ and 0×1 F₂ chickens

		Number mated^b		Four-week percentage of eggs			Egg characteristics (mean±standard deviation)
Line	Mean age (weeks)^a	Males	Females	Production	Fertility	Hatchability	Number tested	Weight (g)	Breadth (mm)	Length (mm)	Index (b/l)
0	36 to 40	6 pooled	30	71.6	92; 9% dead	Not done	100	49.6±2.8	409±11.2	547±21.3	0.75±0.03
0×1 F1	28 to 33	9 single	40	85.1	96.5	93	19	45.0±3.0	Not done	Not done	Not done
0×1 F2	38 to 42	11 single	21	76.3 ^c	83.2	73.3	111	55.9±7.0^d	417±21.1^d	573±34.2^d	0.73±0.03
0	48 to 50	6 pooled	30	41	94.4	78.9	100	55.9±3.7	421±13	596±23	0.71±0.03
0×1 F1	48 to 52	8 single	40	75.3	96; 1% dead	Not done	120	57.9±3.0	425±9	583±20.5	0.73±0.02
0×1 F2	48 to 52	11 single	21	56.5 ^e	91	80.8	100	57.5±5.3^f	423±12^f	587±31^f	0.72±0.03
^a The range in age of the chickens at the time egg collection began is given.
^b Semen was artificially inseminated using the number of males and females indicated.
^c Two hens laid only seven or 12 eggs. When they are excluded 19 hens had 81.5% egg production.
^d Three hens had small eggs. When they are excluded 16 hens had eggs with a mean weight=58.3 g, breadth=423 mm, and length=584 mm.
^e Three hens laid no eggs. When they are excluded 18 hens had 66% egg production.
^f Two of 17 laying hens had small eggs. When they are excluded 15 hens eggs mean weight=58.7 g, breadth=426 mm and length=592 mm.