| The cleanliness of pen is an important factor affecting the volatilization of harmful gases,the water consumption for washing and the amount of labor for cleaning,and also a key index for evaluating the welfare level of pigs.Pigs have the natural behavior habit of excreting at a fixed point far away from the lying area.Under the condition of modern facility breeding,the spatial environment of pen will change the location selection of pig elimination and lying behavior,and then affect the cleanliness of pen.Stocking density is an important indicator of the spatial environment of the pigs,which represents the size of the active space of the pig and has an important impact on the expression of the behavior of the pig.At present,most domestic and foreign researches on the stocking density of pigs are from production performance,physiological health and feeding,drinking water,fighting and other behavioral considerations.However,there are few studies on the effect of stocking density on the behavior of elimination,lying and the cleanliness of pen.In this study,we selected nursery pigs with the same parity and similar weight(240"Duroc×Lardrace×Yorkshire"ternary hybrid pigs weighing about 7 kg),growing pigs(216"Duroc×Lardrace×Yorkshire"ternary cross-breeding pigs weighing about 23 kg),fattening pigs(144"Duroc×Lardrace×Yorkshire"ternary cross-breeding pigs weighing about 57 kg)are randomly divided into4,3,and 3 groups,there are 6,4,and 4 repetitions for each group in each stage.In this study,different feeding densities were set for the three feeding stages of nursery,growing and fattening pigs(Note:In this article,the stocking density"larger or higher"means that the smaller the value of the feeding density,the more pigs per unit area).To study the effects of stocking density on the spatial and temporal distribution of the elimination and lying behavior of pigs at different feeding stages,the proportion of elimination interference and the cleanliness of the pig pen ground.The research results are as follows.1.Pig growth performance.The stocking density has different effects on the daily gain of pigs in different stages,among which the average daily gain of pigs in the nursery stage has no significant difference,and the average daily weight gain in the growing and fattening stages increases significantly with the decrease of feeding density.The average daily weight gain of pigs at the stocking density of 0.90m~2/pig in the rearing stage was significantly higher than that of 0.50m~2/pig and 0.70m~2/pig respectively by 10.1%and 7.2%(P<0.01);the feeding of the fattening stage at1.35m~2/pig Under the density,the average daily weight gain of pigs increased significantly by 6.5%and 6.1%compared with 0.75m~2/pig and 1.05m~2/pig respectively(P<0.05).2.Pig behavior.(1)The daily cycle of elimination and lying behavior of pigs in each feeding stage is basically the same.The elimination behavior mainly occurs in two periods of 07:00-08:00 and 14:00-17:00,and the lying behavior mainly concentrates on 21:00-the next day 06:00.The proportion of the number of pigs lying down was not significantly affected by the stocking density and age,but there was an increasing trend among the three feeding stages,among which the proportion of the number of pigs lying down in the stage of nursery,growing and fattening was 75%,78%and 80%,respectively.(2)With the increase of stocking density and age,the spatial distribution of elimination and lying behavior of pigs showed a consistent trend:the solid ground elimination rate increased,the lying rate decreased;the slatted floor elimination rate decreased,and the lying rate increased.In the stage of nursery,with the increase of feeding age,the lying rate of pigs on the solid floor decreased significantly(P<0.05),and the stocking density had no significant effect on the spatial distribution of excretory lie down behavior of pigs after the stabilization(P>0.05),the choice of lie down area was closely related to the location of heat preservation lamp.In the growing stage,with the increase of feeding age,the elimination rate of pigs on the solid floor increased significantly,and the lying rate decreased significantly.Under the density of0.50m~2/head in the early stage,the elimination rate of the solid floor was 20%higher than that of 0.70m~2/head and 0.90m~2/head(P<0.05),and the lying down rate was18.25%lower than that of 0.90m~2/head(P<0.01).The elimination rate of the solid floor in the later stage was significantly higher than that of the previous stage in the first stage(P<0.01),the rate of lying down was 5%lower than that in the first stage.At the fattening stage,there was no significant effect of feeding age on the spatial distribution of elimination and lying behavior of pigs(P>0.05),at the later stage of feeding,the elimination rate of the solid floor of the pigs at the density of 0.75m~2/pig and 1.05m~2/pig was 27%and 32.75%higher than that of 1.35m~2/head(P<0.05),and the lying rate was23%and 23.75%lower than that of 1.35m~2/head(P<0.01).(3)The interference rate of pig elimination behavior increases with the increase of stocking density and age.The proportion of elimination interference in the growing stage is most significantly affected by the growing density in the late breeding period,the density of elimination disturbance at the density of 0.50m~2/pig is significantly increased by 14.25%compared with 0.7m~2/pig(P<0.05)and 0.9m~2/pig very significant increase of 18.25%(P<0.01).The proportion of interference elimination in fattening stage was only affected by stocking density in the later stage of feeding,and the proportion of disturbed elimination in 0.75m~2/head was 17.25%and 11.25%higher than that in 1.05m~2/head and 1.35m~2/head,and the proportion of interference elimination in the later stage of feeding was 11.25%higher than that in the earlier stage.3.Cleanliness of pen.(1)Stocking density has different effects on the cleanliness of pigpens in different stages.The smaller the stocking density in the early stage of the nursery period,the more serious the pollution in the pigsty;the greater the stocking density during the growing and fattening stages,the more serious the overall pollution of the pens.In the early nursery period,especially at the stocking density of0.40m~2/head,0.50m~2/head and 0.60m~2/head,the polluted area was 4%,7%and 10%higher than that of 0.30m~2/head in the third week;by the fourth week,at the density of0.40m~2/head,the polluted area of solid floor was 11%higher than that of 0.60m~2/head,and the fecal coverage area was also increased from less than 1/3 to 1/3～2/3.In the growing stage,especially under the density of 0.50m~2/pig in the early stage,the proportion of solid floor polluted by feces is 6%and 8%higher than that of 0.70 m~2/pig and 0.90 m~2/pig.The fecal state changes from dry to wet,and the fecal coverage area changes from less than 1/3 to more than 1/3～2/3 of the area of the solid floor.(2)Feeding age also has different effects on the cleanliness of the pigsty at different stages.Among them,the pollution degree of the pigsty in the nursery stage shows a trend of"decrease first and then increase"with the increase of the age,while the stages of growing and fattening as the age of pigs increases,the pollution level of the pigsty becomes higher and higher.With the increase of the age of the pigs during the nursery period,the proportion of the area where the solid floor is contaminated with feces,the status of the feces,and the score of the fecal coverage area all show the same trend as the elimination rate in this area.At the end of the growing stage,the proportion of the solid floor polluted by feces was about 15.3%higher than that at the beginning,at this time,the fecal state was more humid and flakes than that at the beginning,and the number and dispersion of feces were higher.In the fattening stage,with the increase of the age of the pigs,the proportion of the area polluted by feces in the solid floor of the pigsty at the stocking density of 0.75 m~2/pig and 1.05 m~2/pig increased by 4%compared with that in the earlier stage,the fecal state of each density in the later stage was more humid and flakes compared with that in the earlier stage,and the fecal coverage area also increased from 1/3～2/3 in the earlier stage to more than 2/3.To sum up,the effect of stocking density on the growth,behavior and cleanliness of pigs in the nursery period is not obvious and inconsistent,which is a key period for the development of pig behavior rules,the production of pigs should focus on strengthening the training of pig behavior at this stage and guidance.The increase in stocking density during the growing and fattening stages will have different degrees of adverse effects on pig growth,behavior and pigpen cleanliness.The experimental data and rules obtained in this paper can provide technology for piggery design and construction and swine size management for reference,promote green,welfare and healthy development of pig breeding. |
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