Effect of Feed Intake Characteristic on Growth Performance in Luyu-Duroc and Yorkshire
HU Hongmei, ZHANG Yin, GUO Jianfeng, WANG Jiying, SUN Shouli, WANG Huaizhong, LIN Haichao,WANG Yanping, WU Ying*
Institute of Animal Husbandry and Veterinary Medicine Shandong Academy of Agricultural Sciences, Jinan, Shandong 250100, China
Abstract [Objective] To study the effect of feed intake characteristic on growth performance in Luyu-Duroc and Yorkshire. [Method] 89 Luyu-Yorkshire and 82 Luyu-Duroc were chosed and fed in the automatic determination system for swine production, 24h real-time monitoring feed intake traits and growth performance. [Result] It showed that: as feed intake increased, average daily gain (ADG) and weight of 4 months were enhanced, days on test, feed conversion ratio (FCR) and age-corrected of weight at 100 kg were reduced, feed intake positively regulated growth performance of Luyu-Doroc and Yorkshire. Feed intake significantly impacted ADG and days on test (P<0.01), notably affected age-corrected of weight at 100 kg of Luyu-Duroc and FCR of Luyu-Yorkshire (P<0.05), variation tendency of feed frequency was consistent with feed intake and feed time, and the correlation was significant. [Conclusion] The correlation between feed intake traits and growth performance was mainly caused by feed intake, ADG and FCR, however, predictability of feed intake was stronger than ADG and FCR, so in the actual selection feed intake was increased in pig breeding, thus at the same time to enhance ADG and to reduce FCR.
Key words Pig; Feed intake traits; Growth performance; Canonical correlation analysis
The feed intake was not only one of the main factors to limit animal growth performance and genetic potential development and affect weight gain of livestock for meat and feed utilization rate, but the premise to improve production efficiency. The regulation of pig feed intake was mainly short-term by physical (mechanical) and metabolic regulation and also the sensory system. Moreover, environmental conditions, health status, genetic factors, dietary nutrient concentration, etc. all affected porcine feed intake. In the production practice, the importance of animal feed intake is often so underestimated that the animal growth and the benefit of farm are affected. At present, the pig breeding objectives from the past emphasis on growth velocity and cutability has transferred to balance selection, more emphasis on the improve of integrated production efficiency and feed intake has gradually been emphasized. The indicators of feed intake traits and growth performance in 89 Luyu-Yorkshire and 82 Luyu-Duroc were collected by the analysis of variance, simple correlation and canonical correlation, to analyze and approach from different angles and levels the effect of feed intake traits on growth performance, to provide technical support and theoretical basis for superior pig breeding and analyzing the regulatory mechanism of feed intake.
1. Materials and Methods
1.1. Collection of experimental pigs 89 Luyu-Yorkshire and 82 Luyu-Duroc (average parity, healthy and about 30 kg of weight) were randomly divided into 6 groups of 13-15 pigs each respectively, the test ended when the weight reached 100 kg. The pigs were fed with the same basal diet during the trial, diet component and nutritional level were shown in Table 1.
Table.1 The component and nutritional level of diets
|
material
|
diet component
|
item
|
nutritional level
|
|
Corn//％
|
66.0
|
DE MJ//kg
|
3.10
|
|
Fishmeal//％
|
4.0
|
crude protein//%
|
17.45
|
|
Soybean//％
|
21.0
|
Lys//%
|
0.93
|
|
Bran//％
|
4.18
|
crude fibre//％
|
2.61
|
|
Oil//％
|
2.0
|
Ca//％
|
0.68
|
|
Salt//％
|
0.4
|
organic phosphorus//％
|
0.49
|
|
calcium dihydrophosphate ％
|
1.5
|
crude fat//%
|
3.08
|
|
calcium carbonate//％
|
0.4
|
Met//%
|
0.27
|
|
Microelement//%
|
0.5
|
|
|
|
Vitamin//％
|
0.016
|
|
|
|
total
|
100.0
|
|
|
1.2. Breeding and management The experimental pigs were all raised in the automatic determination system for swine production (Osborne, America), each recording station keeping 13-15 pigs free dry powder intake and drinking water. Moreover, pigs were marked with RFID electronic ear tags when entering the stations, by identification of which to 24h real-time monitor the feed intake and growth information. The pigsties and measurement system were kept clean and dry.
1.3. Determination of indicators The feed intake, feed time, feed frequency, ADG, FCR and days on test were recorded, weight of 4 months, backfat of weight at 95-100 kg and weight were also measured to calculate backfat-corrected of weight at 100 kg and age with reference to pig production performance measurement regulations (NY/T822-2004).
1.4. Data statistical analysis The One-Way ANOVA of SPSS 15.0 software was applied to analyze the effect of feed intake on indicators of ADG and FCR, and the effect of species on feed intake traits; Simple correlation analysis of all indicators was performed using Pearson Correlation Coefficients of Bivariate Correlations modular; Canonical correlation was analyzed among two groups of characters (the total feed intake, daily intake, feed frequency and feed time; ADG, FCR, age-corrected of weight at 100 kg and backfat thickness) using Cancorr program of Canonical Correlation modular.
2. Results and Analysis
2.1. Effects of daily feed intake on growth performance in Luyu-Duroc and Yorkshire The effects of daily intake which took 2.0 kg as critical value on growth performance in Luyu-Duroc and Yorkshire was statistically analyzed (Table 2).
Table.2 Effect of feed intake on growth performance in Luyu-Duroc and Yorkshire
|
item
|
Luyu-Duroc
|
Luyu-Yorkshire
|
|
Average daily feed intake≤2.0 kg
|
Average daily feed intake2.0 kg
|
P value
|
Average daily feed intake≤2.0 kg
|
Average daily feed intake>2.0 kg
|
P value
|
|
number of sample
|
66
|
16
|
-
|
51
|
38
|
-
|
|
start weight//kg
|
30.88±0.33
|
30.88±0.31
|
0.996
|
30.58±0.31
|
30.83±0.51
|
0.658
|
|
over weight//kg
|
99.84±0.31
|
100.89±0.28
|
0.107
|
100.73±0.48
|
101.05±0.34
|
0.614
|
|
Average daily feed intake//kg
|
1.75±0.02
|
2.01±0.03
|
0.000
|
1.76±0.03
|
2.10±0.03
|
0
|
|
total feed intake//kg
|
173.11±1.95A
|
181.86±3.48
|
0.046
|
162.95±3.45B
|
178.59±3.63
|
0.003
|
|
feed visits//kg
|
532.03±16.55a
|
559.19±22.29y
|
0.446
|
664.76±32.71b
|
702.83±36.59x
|
0.134
|
|
feed occupany//h
|
161.52±5.75
|
195.22±9.33X
|
0.009
|
153.65±6.51
|
159.79±7.41Y
|
0.536
|
|
days on test//d
|
99.08±1.01A
|
90.69±2.12x
|
0.000
|
92.80±1.61B
|
85.26±1.49y
|
0.001
|
|
ADG//g
|
700.00±7.17A
|
777.91±17.35y
|
0.000
|
765.10±12.77B
|
832.85±13.92x
|
0.001
|
|
FCR
|
2.51±0.03A
|
2.60±0.05
|
0.131
|
2.33±0.05B
|
2.54±0.05
|
0.002
|
|
weight of 4 months//kg
|
44.89±0.87A
|
48.13±1.48Y
|
0.101
|
52.56±1.31B
|
56.48±1.73X
|
0.070
|
|
age-corrected of weight at 100 kg //cm
|
12.52±0.27
|
12.35±0.66
|
0.790
|
12.59±0.30
|
12.24±0.43
|
0.496
|
|
backfat thickness-corrected of weight at 100 kg//d
|
194.81±2.25A
|
185.03±2.51X
|
0.046
|
175.98±2.66B
|
169.76±2.56Y
|
0.103
|
average daily feed intake≤2.0 kg or average daily feed intake>2.0 kg, the differnet superscript small letter in the same line, significant at P<0.05, the differnet superscript capital letter in the same line, significant at P<0.01.
As is shown in Table 2, there was no significant difference between Luyu-Duroc and Yorkshire in the start weight and over weight taking daily intake 2.0 kg as critical value. The average daily feed intake in Luyu-Duroc was 1.75 kg and 2.01 kg respectively while in Yorkshire 1.76 kg and 2.10 kg, and the differences among the intraspecies were significant (P<0.01), the tendency of rise and fall in daily intake was consistent with total feed intake, feed time and feed frequency. The daily feed intake notably affected feed time, days on test, ADG and age-corrected of weight at 100 kg in Luyu-Duroc (P<0.05), and significantly impacted days on test, ADG and FCR in Yorkshire (P<0.01). Therefore, it can be seen that the feed intake in Luyu-Duroc and Yorkshire presented positive correlation with feed frequency, feed time, ADG and weight of 4 months, days on test and age-corrected of weight at 100 kg were reduced, however, the larger the feed intake was, the bigger the FCR was, in other words, the feed conversion ratio was reduced. The FCR in Luyu-Duroc was increased by 9.01%, and the difference was significant (P<0.01), but not significant in Luyu-Yorkshire (P>0.05) increased by 3.59%.
When daily intake was less than or equal to 2.0 kg, the average daily intake of Luyu-Duroc was almost the same with that of Luyu-Yorkshire (P>0.05). Compared with the Luyu-Yorkshire, the total feed intake, days on test, FCR and age-corrected of weight at 100 kg of Luyu-Duroc were significantly enhanced (P<0.01), feed frequency, ADG and weight of 4 months were significantly reduced (P<0.01), but the difference of other indicators was not significant (P>0.05). When daily intake was more than 2.0 kg, the differences of average daily intake between Luyu-Duroc and Yorkshire were not significant (P>0.05). Moreover, the feed time, days on test and age-corrected of weight at 100 kg of Luyu-Duroc were significantly higher than that of Luyu-Yorkshire (P<0.05), but feed frequency, ADG and weight of 4 months were significantly lower (P<0.05), the differences of other indexes were not significant (P>0.05). The feed intake of Luyu-Duroc every time (0.34 kg) were significantly higher than that of Luyu-Yorkshire (0.27 kg), and the difference was significant (P<0.01), but there was no significant difference between their hourly feed intake, 1.04 kg and 1.085 kg respectively. Therefore, it can be seen that under the circumstances of no differences between start weight, over weight and daily intake, ADG and weight of 4 months of Luyu-Yorkshire were significantly higher than that of Luyu-Duroc (P<0.05), age-corrected of weight at 100 kg and days on test were significantly lower than that of Luyu-Duroc (P<0.05). When daily intake was less than or equal to 2.0 kg, the FCR of Luyu-Yorkshire was significantly lower (P<0.05), so was it when the daily intake was more than 2.0 kg, but the difference was not significant (P>0.05), in other words, under the same conditions, the growth potential of Luyu-Yorkshire was higher than that of Luyu-Duroc which also met variety characteristics.
2.2. Correlation coefficient among indicators of feed intake characteristic and growth performance in Luyu-Duroc and Yorkshire It can be seen from Table 3 that daily intake presented extremely significant correlation with total feed intake, ADG and FCR, notable correlation with weight of 4 months, but extremely significantly negative correlation with days on test, and remarkably negative correlation with age-corrected of weight at 100 kg, however, the correlation with feed time, feed frequency and backfat-corrected of weight at 100 kg was not significant. Total feed intake presented extremely significant correlation with feed frequency, feed time and FCR, extremely significantly negative correlation with days on test, and remarkably negative correlation with age-corrected of weight at 100 kg, but there was no significant correlation with ADG, weight of 4 months and backfat-corrected of weight at 100 kg. Feed frequency presented extremely significant correlation with feed time, days on test, FCR and age-corrected of weight at 100 kg, and remarkably negative correlation with ADG, but no significant correlation with backfat-corrected of weight at 100 kg. Feed time was significantly correlated with FCR and presented remarkably negative correlation with weight of 4 months. Moreover, days on test presented extremely significantly negative correlation with ADG and weight of 4 months, and extremely significant correlation with FCR and age-corrected of weight at 100 kg. ADG presented extremely significantly negative correlation with FCR and age-corrected of weight at 100 kg, and extremely significant correlation with weight of 4 months. FCR presented significant correlation and extremely remarkably negative correlation with weight of 4 months and age-corrected of weight at 100 kg respectively. Age-corrected of weight at 100 kg was remarkably correlated with backfat-corrected of weight at 100 kg.
Table.3 Correlation coefficient among traits in Luyu-Duroc and Yorkshire
|
|
total feed intake
|
feed visits
|
feed occupany
|
Average daily feed intake
|
days on test
|
ADG
|
FCR
|
weight of 4 months
|
age-corrected of weight at 100 kg
|
|
feed visits
|
0.440**
|
|
|
|
|
|
|
|
|
|
feed occupany
|
0.308**
|
0.579**
|
|
|
|
|
|
|
|
|
Average daily feed intake
|
0.536**
|
0.056
|
0.212
|
|
|
|
|
|
|
|
days on test
|
-0.375**
|
0.367**
|
0.091
|
-0.577**
|
|
|
|
|
|
|
ADG
|
-0.157
|
-0.235*
|
0.036
|
0.677**
|
-0.877**
|
|
|
|
|
|
FCR
|
0.882**
|
0.354**
|
0.235*
|
0.468**
|
0.332**
|
-0.329**
|
|
|
|
|
weight of 4 months
|
-0.162
|
-0.520**
|
-0.245*
|
0.280*
|
-0.476**
|
0.465**
|
-0.187
|
|
|
|
age-corrected of weight at 100 kg
|
-0.283*
|
0.361**
|
0.167
|
-0.263*
|
0.565**
|
-0.527**
|
0.278*
|
-0.542**
|
|
|
backfat thickness -corrected of weight at 100 kg
|
0.058
|
0.033
|
-0.047
|
-0.047
|
0.092
|
-0.061
|
0.025
|
0.152
|
0.233*
|
the superscript * in the same line, significant at P<0.05, the superscript ** in the same line, significant at P<0.01.
As can be seen from Table 4, daily intake presented extremely significant correlation with total feed intake, ADG and FCR, extremely significantly negative correlation with days on test, but no significant correlation with feed time, feed frequency, weight of 4 months, age-corrected of weight at 100 kg and backfat-corrected of weight at 100 kg. Total feed intake presented extremely significant correlation with feed frequency, feed time, ADG, FCR and weight of 4 months, extremely significantly negative correlation with days on test, but no significant correlation with age-corrected of weight at 100 kg and backfat-corrected of weight at 100 kg. Feed frequency presented significant correlation with feed time, days on test, FCR, age-corrected of weight at 100 kg and backfat-corrected of weight at 100 kg, and remarkably negative correlation with ADG. Feed time was significantly correlated with days on test, FCR and weight of 4 months, and significantly negative correlation with ADG and age-corrected of weight at 100 kg. Days on test presented extremely significantly negative correlation with ADG and weight of 4 months, and extremely significant correlation with FCR and age-corrected of weight at 100 kg. ADG presented extremely significantly negative correlation with FCR and age-corrected of weight at 100 kg, and extremely significant correlation with weight of 4 months. FCR presented extremely significantly negative correlation with weight of 4 months, and significant correlation and extremely remarkably negative correlation with weight of 4 months and age-corrected of weight at 100 kg respectively. Age-corrected of weight at 100 kg was remarkably correlated with backfat-corrected of weight at 100 kg.
Table.4 Correlation coefficient among traits in Luyu-Duroc and Yorkshire
|
|
total feed intake
|
feed visits
|
feed occupany
|
Average daily feed intake
|
days on test
|
ADG
|
FCR
|
weight of 4 months
|
age-corrected of weight at 100kg
|
|
feed visits
|
0.322**
|
|
|
|
|
|
|
|
|
|
feed occupany
|
0.443**
|
0.598**
|
|
|
|
|
|
|
|
|
Average daily feed intake
|
0.575**
|
-0.053
|
0.060
|
|
|
|
|
|
|
|
days on test
|
-0.577**
|
0.433**
|
0.443**
|
-0.328**
|
|
|
|
|
|
|
ADG
|
0.442**
|
-0.345**
|
-0.323**
|
0.414**
|
-0.918**
|
|
|
|
|
|
FCR
|
0.946**
|
0.258*
|
0.340**
|
0.578**
|
0.514**
|
-0.492**
|
|
|
|
|
weight of 4 months
|
0.348**
|
-0.492**
|
0.394**
|
0.157
|
-0.544**
|
0.579**
|
-0.374**
|
|
|
|
age-corrected of weight at 100 kg
|
0.370
|
0.426**
|
-0.325**
|
-0.185
|
0.621**
|
-0.652**
|
0.412**
|
-0.902**
|
|
|
backfat thickness -corrected of weight at 100 kg
|
0.080
|
0.377**
|
0.220
|
-0.068
|
0.162
|
-0.159
|
0.032
|
-0.371**
|
0.355**
|
the superscript * in the same line, significant at P<0.05, the superscript ** in the same line, significant at P<0.01.
2.3. The canonical correlation coefficients between feed intake traits and growth performance of Luyu-Duroc and Yorkshire As can be seen from Table 5, the first and second canonical correlation coefficients between feed intake traits and growth performance of Luyu-Duroc presented extremely significant correlation (P<0.01), the third canonical correlation coefficients reached the level of significant correlation (P<0.05), proportion of canonical correlation coefficients was 98.26%, 1.61% and 0.12% respectively, adding to 99.99%. The first, second and third canonical correlation coefficients between feed intake traits and growth performance of Yorkshire all reached the level of extremely significant correlation (P<0.01), proportion of which was 95.77%, 3.76% and 0.45% respectively, adding to 99.98%. It indicated that the fairly strong correlation existed between feed intake traits and growth performance of Luyu-Duroc and Yorkshire.
Table.5 The canonical correlation coefficients between feed intake traits and growth performance of Luyu-Duroc and Yorkshire
|
breeds
|
canonical correlation coefficient
|
eigen value
|
proportion
|
cumulative proportion
|
probability
|
|
Luyu-Duroc
|
0.997
|
165.9170
|
0.9826
|
0.9826
|
0
|
|
0.855
|
2.7178
|
0.0161
|
0.9987
|
0
|
|
0.413
|
0.2056
|
0.0012
|
0.9999
|
0.028
|
|
0.114
|
0.0132
|
0.0001
|
1.0000
|
0.629
|
|
Luyu-Yorkshire
|
0.995
|
99.2506
|
0.9577
|
0.9577
|
0
|
|
0.892
|
3.8939
|
0.0376
|
0.9952
|
0
|
|
0.565
|
0.4689
|
0.0045
|
0.9998
|
0.001
|
|
0.153
|
0.0240
|
0.0002
|
1.0000
|
0.533
|
2.4. The structure of the canonical variables and analysis between feed intake traits and growth performance of Luyu-Duroc and Yorkshire The structure of canonical variables between feed intake traits and growth performance of Luyu-Duroc (Table 6) presented that the coefficient of daily intake in U1 was the biggest (0.985), in V1 the coefficient of ADG and FCR were the biggest, 0.936 and 0.800 respectively. In U2, the coefficient of total intake was the biggest (1.202), followed by daily intake (0.658),the coefficient of ADG and FCR in V2 were the biggest, 0.417 and 0.662 respectively. In U3, the coefficient of feed frequency was the largest (1.121), then total intake (0.653), and in V3, the coefficient of weight of 4 months was the largest (1.607), next ADG (0.579). It indicated that the trait correlation between feed intake trait and growth performance of Luyu-Duroc was mainly caused by daily intake, total intake, ADG, FCR and weight of 4 months, among which daily intake, ADG and FCR played the most important roles. Among the two groups of traits correlation, it was daily intake, total intake, feed frequency and feed time in order that played a role in feed intake characteristic, and in growth performance ADG, FCR, weight of 4 months, age-corrected of weight at 100 kg and backfat-corrected of weight at 100 kg one by one.
Table.6 The structure of the paired canonical correlation variables for significant canonical correlation
coefficient between feed intake traits and growth performance of Luyu-Duroc and Yorkshire
|
breeds
|
structure of canonical variables
|
|
Luyu-Duroc
|
U1=0.024 total feed intake+0.985 Average daily feed intake -0.002 feed visits+0.009 feed occupany
|
|
V1=0.936 ADG+0.800 FCR-0.007 weight of 4 months+0.015 kg backfat thickness-corrected of weight at 100 kg-0.011 age-corrected of weight at 100 kg
|
|
U2=-1.202 total feed intake+0.658 Average daily feed intake +0.039 feed visits-0.007 feed occupany
|
|
V2=0.417 ADG-0.662 FCR+0.028 weight of 4 months-0.171 backfat thickness-corrected of weight at 100 kg-0.037 age-corrected of weight at 100 kg
|
|
U3=0.653 total feed intake-0.196 Average daily feed intake -1.121 feed visits-0.073 feed occupany
|
|
V3=-0.579 ADG+0.173 FCR+1.067 weight of 4 months-0.159 backfat thickness-corrected of weight at 100 kg-0.132 age-corrected of weight at 100 kg
|
|
Luyu-Yorkshire
|
U1=0.085 total feed intake+0.941 Average daily feed intake -0.023 feed visits-0.021 feed occupany
|
|
V1=0.660 ADG+0.922 FCR+0.007 weight of 4 months-0.017 backfat thickness-corrected of weight at 100 kg+0.004 age-corrected of weight at 100 kg
|
|
U2=-1.433 total feed intake+1.002 Average daily feed intake +0.069 feed visits+0.162 feed occupany
|
|
V2=0.799 ADG-0.452 FCR-0.180 weight of 4 months-0.125 backfat thickness-corrected of weight at 100 kg-0.006 age-corrected of weight at 100 kg
|
|
U3=0.354 total feed intake-0.279 Average daily feed intake -0.726 feed visits-0.475 feed occupany
|
|
V3=-0.097 ADG-0.071 FCR+1.610 weight of 4 months+1.358 backfat thickness-corrected of weight at 100 kg-0.558 age-corrected of weight at 100 kg
|
The structure of canonical variables between feed intake traits and growth performance of Yorkshire presented that the coefficient of daily intake in U1 was the biggest (0.941), in V1 the coefficient of FCR were the biggest, then ADG, 0.922 and 0.660 respectively. In U2, the coefficient of total intake was the biggest, followed by daily intake, 1.433 and 1.002 respectively, the coefficient of ADG and FCR in V2 were comparatively large, 0.799 and 0.452 respectively. In U3, the coefficient of feed frequency was the largest, then feed time, and in V3, the coefficient of weight of 4 months was the largest (1.610), next age-corrected of weight at 100 kg (1.358). It indicated that the trait correlation between feed intake trait and growth performance of Yorkshire was mainly caused by daily intake, total intake, feed frequency, ADG, FCR and weight of 4 months, among which daily intake, ADG and FCR played the most important roles. Among the two groups, daily intake played the largest roles, followed by total intake, feed frequency and feed time in feed intake traits, and in growth performance it was by turn FCR, ADG, weight of 4 months, age-corrected of weight at 100 kg and backfat-corrected of weight at 100 kg that worked.
3. Discussion
The correlation between feed intake traits and growth performance of Luyu-Duroc and Yorkshire was both from feed intake, feed frequency, ADG, FCR and weight of 4 months, which was consistent with simple correlation coefficient among traits. Among the simple correlation coefficient of 10 traits between feed intake traits and growth performance, the correlation coefficient of total intake and FCR of Luyu-Duroc was the biggest (0.882), followed by ADG and daily intake (0.677), then in turn feed frequency and weight of 4 months, daily intake and FCR, the correlation was all significant. The correlation coefficient of total intake and FCR of Yorkshire was the biggest, then daily intake and FCR, feed frequency and weight of 4 months, total intake and ADG, daily intake and ADG in order, the correlation was all significant. Therefore, it can be seen that the predictability of feed intake and feed frequency was fairly strong to ADG, FCR and weight of 4 months, vice versa, it illustrated that among the 10 traits between feed intake characteristic and growth performance of Luyu-Duroc and Yorkshire, feed intake, feed frequency, ADG and FCR played a principal role, and it also indicated that feed intake and feed frequency had a comparatively large effect on pig growth performance.
The simple correlation and variance analysis among the traits indicated that feed intake, feed frequency and feed time significantly affected the growth performance of Luyu-Duroc and Yorkshire, and daily intake extremely significantly impacted days on test and ADG. Daily intake of Yorkshire extremely significantly affected FCR, daily intake of Luyu-Duroc significantly affected age-corrected of weight at 100 kg. It was identical with the findings of Clutter et al.[1] who determined the feed intake of the crossbred (Duroc × Hampshire of age of 9 weeks to weight of 100 kg) and discovered average daily intake of quick growth strain was 2.72 kg, and that of slow growth strain was 2.01 kg, the difference was significant (P<0.05). The study indicated that the feed intake variation of commercial pig farms can reach 25%. The coefficient of variance of daily intake of Luyu-Duroc and Yorkshire was 10.04% and 12.83% respectively, and that of total intake was 11.05% and 14.62% respectively, they were all between 10% and 15%, moreover, the coefficient of variance of feed intake was comparatively large possibly due to pig feed intake and inheritance. Whittington et al. thought the feed intake ability of Duroc was stronger than that of Yorkshire, NGT Large White and Hampshire etc.[2], which was consistent with the results. Total intake of Luyu-Duroc at 30-100 kg was higher than Yorkshire, feed intake every time was significantly higher than Yorkshire within the same period of time, but the growth potential of Luyu-Duroc was lower than that of Yorkshire which was possibly relevant to the higher daily intake of Yorkshire. Moreover, although the feed intake ability every time of Luyu-Duroc was stronger within the same time, and during the test, the total intake and feed time was higher than that of Luyu-Yorkshire (174.82vs169.63 kg, 168.10vs156.27 h), the difference was not significant (P>0.05), age of weight at 100 kg of Luyu-Duroc was significantly higher than Yorkshire (192.94vs173.27 d), and at the same time, ADG and weight of 4 months were significantly lower (715.19vs794.03 g, 45.56vs54.25 kg), FCR was significantly higher (2.53vs2.41), and daily intake was significantly lower (1.80vs1.90) (P<0.01).
Many investigations indicated that MC4R played a critical role in regulating animal appetite and gaining weight, and thought it as inheritable[3]. Houston et al. discretely chose 7 generation of Large White with different MC4R genotypes, and determined the growth performance, the ADG and average daily intake of Asp298 homozygote pigs were 733 g and 1.93 kg respectively, while the ADG and average daily intake of Asn298 homozygote pigs can reach 805 g and 2.10 kg respectively[4]. Kim et al. used Large White, Landrace, Duroc and Meishan pig to organize 5 commercial pigs strains, MC4R as candidate genes for study and found that significant correlation existed between different MC4R genotypes and backfat thickness, growth rate and feed intake[6].
4. Summary
The variation tendency of feed time was consistent with feed intake and feed frequency in Luyu-Duroc and Yorkshire, significantly impacting the growth performance indicators such as ADG, days on test and FRC, and daily feed intake positively regulated the growth performance in pigs. Combined with the automatic determination system for swine production, daily intake, feeding behaviour and growth performance of each pig can be exactly determined in group feeding conditions of free intake, and it was possible to select the pigs simultaneously binding with the regulation of the appetite studies at the molecular level, thus to improve intake capacity of pigs and the breeding efficiency.
In practical breeding and selection, choice of intake can simultaneously achieve the objective of improving growth performance which was of great guiding significance to reduce determination of traits, improve work efficiency and lower selection cost. Moreover, with the application of automatic determination system for swine production, daily intake, feeding behaviour and growth performance of each pig can be exactly and chronically determined, and it was possible to select the pigs simultaneously binding with the regulation of the appetite studies at the molecular level, thereby regulating intake of pigs to improve the breeding efficiency.
Acknowledgments
This work was supported by the Agricultural Elite Project of Shandong Province (2010LZ013-02) and the National Pig Industry Technology System (CARS-36).
References
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[2] WHITTINGTON D L, NYACHOTI C M, PATIENCE J F, et a1. Feed intake A checklist of nutritional, environmental and management strategies to achieve success[C]. Prairie Swine Centre Inc, 2007.
[3] BURGOS C, CARRODEGUAS J A, MORENO C，et al. Allelic incidence in several pig breeds of a missense variant of pig melanocortin-4 receptor (MC4R) gene associated with carcass and productive traits; its relation to IGF2 genotype[J]. Meat Science, 2006, 73:144-150.
[4] HOUSTON R D, CAMERON N D, RANCE K A, et al. A melanocortin-4 receptor (MC4R) polymorphism is associated with performance traits in divergently selected large white pig populations [J]. Animal Genetics, 2004, 35:386-390.
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About the author
HU Hongmei (1976-), female, P.R. China, Assistant Researcher, Master, working at research about pig nutrition.
*Corresponding author. WU Ying (1956-), female, Researcher, working at research about pig genetics and breeding and nutrition.
Tel:13953157118;E-mail:huhongmeipatty@163.com