1. Crossbreeding for
the Production of
Market Hogs
BY: V.G. Argaῆosa
Reported by :
Algeron J. Deterala
MSA Animal Science
Student

2. Introduction
O Experts all over the world recommend
crossbreeding for the production of market
hogs.
O This technology resulted in the production
of the so-called “hybrid pigs” many of
which have been introduce to the
Philippines.
O Landrace, Large White, Duroc, Peitrain
and many other standard breeds have
also been imported from other countries.

3. Objective
O This paper aims to synthesize the results
of cooperative studies between the
University of the Philippines Los Baῆos
and Non-government organizations on the
productive and reproductive performance
of purebred pigs and their crosses.
O The available information may be used in
the development of sound swine breeding
programs specific for the Philippines.

4. Results
O The results of these studies comparing
the production performance of the
imported pigs were summarized by
Argaῆosa et al.(1980).
O They reported that no two breeds did
miserably poor while many of these
animals had better average performance
in some production traits than the same
breed evaluated in other countries.

5. O They concluded that breeding animals
should be tested and selected under the
conditions where their progenies are
expected to perform.

6. Table 1.Production Performance of Purebred
Yorkshire, Landrace and Duroc Gilts and
Boars
(Argañosa et al. 1986)
Parameters
Breed (Gilts)1 Breed (Boars)
Yorkshire Landrace Duroc Yorkshire Landrace Duroc
No. of Animals
Initial age, days
Initial weight, kg
Final weight, kg
Days on test
ADG, g
Backfat Thickness, cm
Feed Efficiency
A.D.Feed Intake, kg
Adjusted 180-day wt2,
kg
3187
84b
26.1b
90.6a
98b
670a
2.51a
2.67b
1.71b
89.7
1806
84b
25.8b
90.2b
105a
626a
2.39c
2.68b
1.61c
86.0
1131
89a
26.6a
90.6a
97c
671a
2.40b
2.72a
1.78a
87.9
1882
85b
27.2a
90.7
82a
784a
2.54a
2.41b
1.87a
97.8
1100
85b
26.8b
90.5
89a
727a
2.36c
2.48a
1.79c
93.6
881
88a
27.2a
90.6
84b
76.3b
2.45b
2.49a
1.88a
94.8
1 Data from the Gilts and boars were separately analyzed. Any two means in the same row followed by the same letter are
not statistically different.
2. Recomputed by the reviewer

7. Table 2.Production Performance of Gilts
belonging to Different breed-groups
(Napoles et al.1986)
Parameters
Breed-group1
Purebred Pietrain crossed with
Yorkshire Duroc Pietrain Yorkshire Duroc Hampshir
e
No. of Animals
Initial age, days
Initial weight, kg
Final weight, kg
Days on test
ADG, g
Backfat Thickness, cm
Feed Efficiency
A.D.Feed Intake, kg
Adjusted 180-day wt2,
kg
91
87.4c
27.5a
90.5ab
101.4b
635c
2.49a
2.78a
1.75a
86.3
51
92.3b
27.2ab
90.8a
102.0b
629c
2.35b
2.71a
1.74a
84.1
44
100.8a
27.0b
90.0ab
111.9a
572d
1.97e
2.58b
1.42d
76.2
81
92.3b
27.8a
89.9b
97.0c
694c
2.15cd
2.59b
1.63c
85.5
53
91.1b
27.2ab
90.6ab
93.4c
679a
2.18c
2.56b
1.69b
88.4
182
89.3bc
27.4ab
90.4ab
95.4c
667b
2.11d
2.56b
1.64bc
88.1
1 Any two means in the same row followed by the same letter are not statistically different.
2 Recomputed by the reviewer

8. Table 3.Production Performance of Boars
belonging to Different breed-groups
(Napoles et al.1986)
Parameters Purebred Pietrain crossed with
Yorkshire Duroc Pietrain Yorkshire Duroc Hampshir
e
No. of Animals
Initial age, days
Initial weight, kg
Final weight, kg
Days on test
ADG, g
Backfat Thickness, cm
Feed Efficiency
A.D.Feed Intake, kg
Adjusted 180-day wt.2,
kg
82
87.2d
27.7
90.7
88.5c
720a
2.53a
2.45b
1.82b
92.9
38
89.2cd
27.7
90.5
87.8c
724a
2.42b
2.64a
1.90a
92.1
69
103.0a
26.9
90.2
108.0a
594c
1.85d
2.65a
1.55d
77.0
90
91.3bc
27.4
90.8
94.8b
678b
2.08c
2.45b
1.60d
87.8
45
93.7b
27.5
90.7
87.9c
727a
2.09c
2.45b
1.70c
89.9
179
89.9cd
27.4
91.2
91.3bc
706ab
2.07c
2.45b
1.68c
90.6
1 Any two means in the same row followed by the same letter are not statistically different.
2 Recomputed by the reviewer

9. Table 4.The Reproductive Performance of
Yorkshire, Landrace and Duroc Breeds
(Siagian et al. 1986)
Parameters Yorkshire Landrace Duroc
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning
based on
Total pigs born
Pigs born alive
30-day old weight, kg2
Internal between, days
Weaning to conception
Two farrowings
Pigs weaned/sow/year
9.25a
0.86a
10.11a
6.77a
7.58b
80.71b
75.35b
4.97
25.2b
172.1b
16.07
9.22a
0.86b
9.91b
5.30b
7.87a
84.77a
80.13a
5.24
31.2a
181.2a
15.82
7.78b
0.69b
8.46c
6.81a
5.05c
64.71c
60.50c
4.89
23.9b
169.1b
10.91
1 Any two means in the same row followed by the same letter are not statistically different.
2 Recomputed by the reviewer

10. Table 5.The Reproductive Performance of
Sows belonging to different Breeds
(Argañosa et al. 1988)
Parameters Purebred Pietrain crossed with
Yorkshire Duroc Pietrain Yorkshire Duroc Hampshire
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning based
on
Total pigs born
Pigs born alive
30-day old weight, kg2
Internal between, days
Weaning to
conception
Two farrowings
Pigs weaned/sow/year
8.82ab
1.00
9.82ab
10.39
7.20abc
72.55bc
80.03ab
4.96
26.7
166.4b
15.77
8.10ab
0.66
8.76bc
5.35
6.24c
66.82c
73.39b
4.79
26.8
174.5b
13.04
9.05ab
0.68
9.73abc
6.70
8.05a
83.50a
89.60a
4.51
38.6
194.4a
15.13
9.27a
0.70
9.97a
6.16
7.73ab
81.11ab
86.18a
4.81
36.8
180.6ab
15.61
8.47ab
1.16
9.63abc
10.87
7.00abc
73.65abc
82.67ab
5.09
31.4
178.8ab
14.28
7.93b
0.69
8.63c
7.31
6.87bc
80.52ab
80.98a
5.44
20.1
175.5ab
14.29
1 Any two means in the same row followed by the same letter are not statistically different.
2 Recomputed by the reviewer

11. Table 6.The Reproductive Performance of
Sows belonging to Different Breed Groups
(Argañosa et al. 1991)
Parameters Lndrac
e
Yrkshir
e
Lndrce x
yrkshire
Duroc Pietrain Duroc x
Petrain
F1 Sow
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning based
on
Total pigs born
Pigs born alive
30-day old weight, kg2
Internal between, days
Weaning to
conception
Two farrowings
Pigs weaned/sow/year
Farrowing rate ,%
8.64b
0.23c
8.87b
2.67d
7.81b
87.32a
90.27a
7.04a
18.3
168.7
17.45c
76.82ab
8.90ab
0.29b
9.19ab
3.14cd
8.04ab
88.13a
91.26a
6.79b
18.6
164.5
18.02bc
78.78a
8.85ab
0.29b
9.14ab
3.16cd
8.19a
89.66a
92.49a
7.00a
15.6
161.9
18.59ab
77.65ab
7.34d
0.40a
7.73d
5.18a
5.86e
75.26c
79.39c
6.26c
17.9
161.9
13.23e
73.92b
7.73c
0.36ab
8.09c
4.36ab
6.02d
74.57c
77.89c
6.27c
19.1
155.2
13.29e
66.58c
7.98c
0.29b
8.27c
3.65bc
6.93c
83.43b
86.59b
6.75b
20.3
194.5
15.41d
68.21c
9.05a
0.30b
9.35a
3.42bcd
8.37a
89.39a
92.57a
7.09a
16.3
160.7
19.04a
79.19a
1 Any two means in the same row followed by the same letter are not statistically different.
2 Recomputed by the reviewer

12. Table 7.The Reproductive Performance of
Sows from Different breed groups in Farm A
(Somchai,1992)
LL YY LY YL L(LY) Y(LY) D(LY) (PD)(LY) P(LY) L(YL) Y(YL) D(YL) (PD
g
ased
g
ays
ear
8.73c
0.33
9.06b
2.66
8.17cd
90.24b
93.34bc
7.45abc
18.50a
162.97a
18.53c
8.71c
0.42
9.13b
3.40
7.93d
86.77c
90.47c
7.30c
13.43bc
157.20b
18.26c
8.72c
0.34
9.05b
2.82
8.24c
90.52b
93.91ab
7.48abc
14.22b
158.76b
19.62bc
8.77bc
0.35
9.05b
2.82
8.24c
90.52b
93.91ab
7.48abc
14.22b
158.76b
19.62bc
9.63a
0.31
9.94a
2.21
9.02a
92.15ab
94.94ab
7.51abc
16.80ab
161.35ab
19.96abc
9.27a
0.34
9.61a
2.56
8.80a
91.71ab
94.98ab
7.53ab
12.20bc
156.02b
20.87a
9.35a
0.30
9.65a
2.54
8.39a
92.23ab
95.03ab
7.53ab
15.25b
159.48b
20.85a
9.34a
0.32
9.66a
2.54
8.89a
92.12ab
95.27ab
7.63bc
12.97bc
157.19b
20.49ab
9.47a
0.22
9.69a
1.70
8.90a
92.46ab
94.54ab
7.44abc
11.41bc
156.23b
20.69ab
9.92a
0.40
9.69a
2.62
8.77a
90.16bc
93.67abc
7.43abc
15.05b
159.54b
19.78abc
9.13ab
0.42
9.55a
3.37
8.66ab
90.67b
94.48ab
7.51abc
10.94c
155.14b
20.46ab
9.22a
0.28
9.49a
1.78
8.80a
92.96a
95.53a
7.65a
13.26bc
157.54b
20.47ab
7.6
0.
9.9
3.
9.1
91.6
95.4
7.3
15.3
159
21.
1 Any two means in the same row followed by the same letter are not statistically different.
2 First letter represents breed of sire and second letter represents breed of dam;
L=Landrace:Y=Yorkshire;D=Duroc;P=Pietrain;(YL)=F1 sows coming from Landrace boar
and Yorkshire sow and so on down the line.

13. Table 8.The Reproductive Performance of
Sows from the Different breed groups in
Farm B (Somchai,1992)
Parameters
LL YY LY YL L(LY) Y(LY) D(LY) L(YL) Y(YL) D(YL) Avg
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning based
on
Total pigs born
Pigs born alive
30-day old weight, kg
Interval between, days
Weaning to
conception
Two farrowings
Pigs weaned/sow/year
9.46cd
0.78ab
10.22bc
7.07ab
8.31b
81.81b
87.29b
6.66ab
19.04a
168.14a
18.69de
9.19d
0.88a
10.06c
8.60a
7.81c
71.10c
83.12a
6.43d
11.77c
160.41c
18.13e
9.81abc
0.83a
10.73a
7.33a
8.69ab
82.54b
88.74ab
6.64ab
14.88b
163.81b
19.80cd
9.69bc
0.62bc
10.31bc
5.32bc
8.39b
82.38b
86.96b
6.62bc
14.28b
162.91b
19.36d
9.56cd
0.54c
10.11c
4.84c
8.64ab
86.80a
90.96a
6.72a
9.39d
154.93d
20.59bc
9.77
0.59c
10.36bc
4.90c
8.60ab
83.79b
87.69b
6.61c
9.25d
153.99d
20.81abc
9.83abc
0.47c
10.30bc
4.22c
8.87a
87.05a
90.20ab
6.52cd
9.83cd
155.11d
21.23ab
9.55abc
0.57c
10.11c
5.06bc
8.83ab
87.43a
91.19a
6.71ab
7.30d
152.83d
21.07abc
9.97ab
0.58c
10.55ab
5.30bc
8.70ab
83.66b
87.87ab
6.63abc
8.26d
153.87d
21.06abc
10.12a
0.52c
10.63ab
4.59c
8.93a
84.47ab
87.81ab
6.52cd
8.94d
154.95d
21.59a
9.69
0.63
10.33
5.72
8.58
83.72
88.18
6.61
11.25
158.01
20.24
1 Any two means in the same row followed by the same letter are not statistically different.
2 First letter represents breed of sire and second letter represents breed of dam;
L=Landrace:Y=Yorkshire;D=Duroc;P=Pietrain;(YL)=F1 sows coming from Landrace boar
and Yorkshire sow and so on down the line.

14. Table 9.The Effects of Breed of Sows on the
different reproductive traits in Farm A
(Somchai. 1992)
Parameters
Breed of Sows 1,2
Landrace
(LL)
Yorkshire
(YL)
Landrace x
Yorkshire
(LY)
Yorkshire x
Landrace
(YL)
Average
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning based
on
Total pigs born
Pigs born alive
30-day old weight, kg
Internal between, days
Weaning to
conception
Two farrowings
Pigs weaned/sow/year
8.84b
0.31
9.15b
2.48
8.31b
90.76b
93.53b
7.45ab
17.58a
161.93a
18.90b
8.81b
0.34
9.15b
2.87
8.18b
88.98c
92.1c
7.34c
13.91b
158.15b
19.26b
9.40a
0.30
9.70a
2.35
8.93a
92.27a
95.15a
7.43bc
13.61b
157.90b
20.74a
9.34a
0.33
9.67a
2.46
8.89a
92.09ab
95.17a
7.56a
12.58b
156.95b
20.47a
9.10
0.32
9.42
2.54
8.58
91.03
94.02
7.45
14.40
158.71
19.85
1 Any two means in the same row followed by the same letter are not statistically different.
2 First letter represents breed of sire and second letter represents breed of dam;
L=Landrace:Y=Yorkshire;D=Duroc;P=Pietrain;(YL)=F1 sows coming from Landrace boar and Yorkshire
sow and so on down the line

15. Table 10.The Effects of Breed of Sows on the
different reproductive traits in Farm B
(Somchai. 1992)
Parameters
Breed of Sows
Landrace
(LL)
Yorkshire
(YL)
Landrace x
Yorkshire
(LY)
Yorkshire x
Landrace
(YL)
Average
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning based
on
Total pigs born
Pigs born alive
30-day old weight, kg2
Internal between, days
Weaning to
conception
Two farrowings
Pigs weaned/sow/year
9.70ab
0.64b
10.34ab
5.59b
8.50bc
83.12b
87.74bc
6.60a
16.19a
165.12a
19.43b
9.65b
0.81b
10.56a
7.50a
8.45c
80.60c
86.39c
6.51b
13.72b
162.53b
19.40b
9.73ab
0.53b
10.27b
4.65b
8.72ab
85.94a
89.68c
6.51b
13.72b
162.53b
19.40b
9.97a
0.53b
10.53a
4.99b
8.85a
84.89ab
6.62a
8.72c
8.72c
154.54c
21.32a
9.76
0.64
10.41
5.74
8.59
83.40
87.95
6.60
11.96
161.68
20.22
1 1 Any two means in the same row followed by the same letter are not statistically different.
2 First letter represents breed of sire and second letter represents breed of dam;
L=Landrace:Y=Yorkshire;D=Duroc;P=Pietrain;(YL)=F1 sows coming from Landrace boar and Yorkshir

16. Table 11. The effects of breed of boar on the
different reproductive traits in Farm A
(Somchai. 1992)
Parameters
Breed of Boar2
Landrace
(LL)
Yorkshir
e (YY)
Duroc
(DD)
Peitrain x
Duroc
Pietrain
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning based
on
Total pigs born
Pigs born alive
30-day old weight, kg
Interval between, days
Weaning to
conception
Two farrowings
Pigs weaned/sow/year
9.02
0.34ab
9.35
2.60
8.54
91.37a
94.61
7.51
15.2a
159.75a
19.78
8.99
0.38a
9.37
3.00
8.42
89.89b
93.34
7.47
13.44b
157.38b
19.76
9.02
0.30b
9.32
2.34
8.54
91.34ab
94.07
7.43
15.69a
159.95a
19.92
9.15
0.35ab
9.50
2.92
8.65
90.81ab
94.22
7.39
14.97ab
159.13ab
19.99
9.31
0.24b
9.55
1.86
8.73
91.71a
93.79
7.43
12.77b
157.45ab
19.77
Any two means in the same row followed by the same letter are not statistically different.

17. Table 12. The effects of breed of boar on the
different reproductive traits in Farm B
(Somchai. 1992)
Parameters
Breed of Boar
Landrace
Yorkshire
Duroc Average
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning based
on
Total pigs born
Pigs born alive
30-day old weight, kg2
Interval between, days
Weaning to
conception
Two farrowings
Pigs weaned/sow/year
9.74
0.67
10.41
5.88
8.70
84.83a
89.78a
6.70a
12.89a
160.23a
20.26b
9.71
0.66
10.37
5.92
8.42
81.93b
86.58c
6.58b
10.97b
157.85b
19.95b
9.90
0.58
10.49
5.25
8.76
84.17a
88.10b
6.49c
12.32a
159.63a
20.59a
9.76
0.64
10.41
5.74
8.59
83.40
87.95
6.60
11.96
161.68
20.22Any two means in the same row followed by the same letter are not statistically
different.

18. Table 13. Production performance of barrows and
gilts from two breed groups of market hogs
(Somchai,1992)
(Somchai.1992)
Parameters
Breed Group * Sex Averag
e
Purebred Gilts
D(LY) D(YL) Barrow Gilt Landrac
e
Yorkshir
e
No. of Animals
Initial age, days
Initial weight, kg
Final weight, kg
Days on test
ADG, g
Backfat Thickness,
cm
Feed Efficiency
A.D.Feed Intake, kg
Adjusted 180-day
wt.kg
Age at 90-kg weight,
days***
40
82.0
34.8
91.3**
73.2
778
1.35
3.03
2.35**
106.1
153
40
81.5
35.3
90.7
70.4
796
1.47
3.16
2.51
107.8
151
40
82.0
36.4
91.8**
68.0**
821
1.45
3.13
2.56**
110.4**
147
40
81.5
33.7
90.1
75.5
753
1.37
3.07
2.30
103.5
157
80
81.8
35.1
91.6
71.8
78.7
1.41
3.10
2.43
106.9
152
40
71.6
26.4
91.0
93.4
69.5
1.32
99.38
162
40
73.4
26.1
90.7
90.2
71.7
1.34
99.83
162
* D = Duroc (Terminal sire)
(LY)= F1 sows coming from Landrace boar and Yorkshire sow
(YL)= F1 sows coming from Yorskhire boar and Landrace Sow
** Significantly different at <0.05
*** Recomputed by the reviewer

19. Table 14.Percentage Heterosis in selected
traits realized in Crossbred (Arganosa et
al.1991)
Traits
Group
Lndrce x
Yorkshire
Duroc x
Pietrain
Crossbred
Sows x
Terminal
Shire
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning
based on
Pigs born alive
weaning weight, kg
Pigs weaned/sow/year
0.91
11.54
1.22
3.34
1.90
1.23
4.87
5.91
-23.68
4.85
16.67
10.11
7.74
16.21
11.01
-6.25
10.39
20.74
9.29
7.53
22.86

20. Table 15.Percentage heterosis in selected
traits realized in F1 sows (Somchai,1992)
Traits Farm A Farm B
Litter size at birth
Born alive
Stillborn
Total
Percent stillborn
Litter size at weaning
Percent weaning
based on
Total pigs born
Pigs born alive
30-day old weight, kg2
Internal between, days
Weaning to conception
Two farrowings
Pigs weaned/sow/year
6.18
-3.08
5.85
8.07
2.57
2.49
1.35
-16.38
-1.64
7.99
1.60
-26.90
-48
3.66
4.34
2.50
0.99
-38.79
-5.60
8.76

21. Summary
O The average reproductive and productive
performance of purebred Landrace,
Yorkshire, Duroc, and Peitrain and
crossbred litters and crossbred sows
involving these four breeds were
summarized.
O After about 15 years of selecting, breeding
and evaluation, the following were found
relevant.

22. 1. Imported purebred Landrace, Yorkshire,
Duroc and Petrain and their purebred
and crossbred offspring did not perform
as good as the same breeds in other
temperate countries. However, their
performance was as good as those
found in previous studies reported under
Philippine conditions.
2. The white breeds had higher
reproductive performance than the
colored breeds.
3. The crossbred litters performed better
than the purebred parental breeds.

23. 4. The crossbred Landrace x Yorkshire or
Yorkshire x Landrace sows mated to either
parental breed or terminal sires performed
better then purebred sows.
5. The market hogs produced out of Landrace x
Yorkshire or Yorkshire x Landrace sows
mated to Duroc boars averaged 90 kg at
152 days.
6. Heterosis was highest in crossbred sows mated
to terminal sire.
7. No information is available on traits associated
with carcass desirability. The need for live
animals and carcass evaluation is very
relevant.

24. Literature Cited
O ARBOLEDA,C.R. VG.
ARGAÑOSA,PARKER,A.L.LAMBIO,OA,PALAD,
FF PENALBA,OL BONDOC and N.A. CARIGMA
1985a Philippine livestock. Imports then and now.
Research at Los Baños 4(2).6-9, 23.
O ARBOLEDA,C.R. VG.
ARGAÑOSA,PARKER,A.L.LAMBIO,OA,PALAD,
FF PENALBA,OL BONDOC and N.A. CARIGMA
1985b Improvement of Philippine livestock.
Imports then and now. Research at Los Baños
4(2).6-9, 23.

25. O ARGAÑOSA VG.JV SERRANO,JR and RP
REYES 1979b, Production performance of
imported Landrace,Welsh,Yorkshire and synthetic
line of swine from England. Phil.J.Vet.Animal
Sci.5(3) 170-178.
O ARGAÑOSA VG, LP NAPOLES and AG
AQUINO 1988. Comparative reproductive
performance of purebred Pietrain swine and their
crossbreds with Duroc, Yorkshire and Hampshire
Phil.Agr.71 (1).104-113.
O ARGAÑOSA VG,OM GATMAITAN,MO
VILLETTA and PRL HUBILLA 1991.The
performance of purebred and crossbred sows
Asian-Australasian, J.Animal Sci.4 (2) 143-150.

26. O ARGAÑOSA
VG,PH.SIAGIAN,AG./AQUINO, CC
LOPEZ and AL DE GUZMAN 1986.
Productive performance of Yorkshire,
Landrace and Duroc breeds. Phil
Agr.69 (2)119-129.
O ARGAÑOSA VG.TS SAN JOSE, DMT
MATA,JV SERRANO,JR and RP REYES
1980. Production performance of imported
pigs in the Philippines. Paper presented
during the First Asian-Australasian Animal
Science congress, Kuala Lumpur,
Malaysia. 31.p

27. O ARGAÑOSA VG.TS SAN JOSE, DMT
MATA,JV SERRANO,JR and RP REYES
1979a. The Reproduction performance
of four imported breeds of swine from four
countries. Phil.J.Vet .Animal Science.5 (1)
29-48.
O BOMMELI,H and L.BUTLER 1976.Swiss
Improved Landrace Breed Society Annual
Report Animal Breed Abrstr.44 (7);368.
O BUTLER,L.1977.Improved Landrace
Breed Society. Annual Report. Animal
breed Abstr 45 (10) 568.

28. O RIGOR,EM,and RC. FAJARDO 1967.
The Performance of Large white under
Los Baños conditions.Phil.Agr.51 (3) 206-
210.
O RIGOR,EM,RC. FAJARDO and MG
SUPNET 1967A. Performance of
Philippine pig X Landrace x Philippine pig
crosses.Phil.Agr.50 (9) 861-865.
O RIGOR,EM,RC. FAJARDO and PL
BENNAGEN.1967B. The performance of
large white x Philippine pig crosses (F2)
and the inter se mated (F3)
pigs.Phil.Agr.51 (6) 536-540.

29. O SOMCHAI ,ORANKANOK
1992.Performance of purebred and
reciprocal crossbreed Landrace and
Yorkshire sows from two commercial
farms.Phd.thesis.University of the
Philippines los Baños,College, Laguna.
O VARJAN,RS 1968.Welsh pigs at Ukrania
Animal Breed.Abstr 36 (1) 93.
O WACHLE,E and M.MAURER 1973.Swiss
Yorkshire Breeders Society Annual report
1972.Animal Breed Abstr.41(10)504.

30. Reference
O The Philippine Agriculturist Volume 77
no.1
pages 31-45.

31. Thank you!!