Zhengxiang Shi

Effects of neoprene mat on diarrhea, mortality and foreleg abrasion of pre-weaning piglets

Modern commercial swine farrowing crates are typically equipped with slatted iron floor to improve management efficiency (e.g., ease of manure handling, cleanliness of the farrowing crates and hence improved animal hygiene). However, the bare and hard floor surface can impair the welfare of the sow-litter because of some undesirable impacts on the pigs, such as foreleg abrasion, large temperature gradients between the cold floor surface and the abdomen of the piglets (hence higher susceptibility to diarrhea), and higher pre-weaning mortality or morbidity. Although straw bedding has been shown to be conducive to providing better environment for the sow-litter, use of straw creates challenges in terms of economics, hygiene and manure handling. This study investigates the use of neoprene mat (NM) in key areas of the farrowing crates - underneath the sow and in the piglet suckling area to improve the microenvironment and hence welfare of the sow-litter. Two experiments were conducted, each involving 12 sow-litters. The first experiment was to evaluate the thickness of a rectangular-shaped NM (7, 10 or 13 mm) vs. the slatted iron floor (control or Ctrl) and collect the corresponding animal response data; while the second follow-up experiment was to verify the benefits of supplying an improved, double concave (or H)-shaped NM with 10mm thick (CNM10) vs. Ctrl for the farrowing operation. Results of both experiments demonstrated considerable benefits of the NM placement in the farrowing crates. Specifically, the NM reduced the piglet foreleg lesion area and joint swellings (0% for NM vs. 8-10% for Ctrl during suckling periods in both Expts 1 and 2, P<0.001); reduced pre-weaning piglet crushing mortality (18.5+/-5.0%, 6.7+/-3.3% and 9.1+/-5.2% and for Ctrl, NM7 and NM10 and in Expt 1, P<0.05); and reduced piglet diarrhea morbidity (0.6+/-0.2% for CNM10 vs. 2.7+/-0.3% for Ctrl in Expt 2, P<0.01). Piglets in the NM litters had smaller temperature gradients between the abdomen and the contact floor surface (3.8+/-2.3 degrees C for NM vs. 7.6+/-0.5 degrees C for Ctrl in Expt 1, P<0.001; 9.2+/-0.5 degrees C for CNM10 vs. 15.9+/-0.5 degrees C for Ctrl in Expt 2, P<0.001). Moreover, sows in the NM regimens showed longer transition time when changing from standing to lying position (7.4+/-0.3s for CNM10 vs. 4.5+/-0.2s for Ctrl in Expt 2, P<0.05), indicative of more floor comfort for the NM condition. Results of this study suggest that supply of NM underneath the sow and in the piglet suckling area is conducive to enhancing comfort, health and welfare of the sow and litter.

Greenhouse gas emissions from dairy open lot and manure stockpile in northern China: A case study

ABSTRACT The open lots and manure stockpiles of dairy farm are major sources of greenhouse gas (GHG) emissions in typical dairy cow housing and manure management system in China. GHG (CO2, CH4 and N2O) emissions from the ground level of brick-paved open lots and uncovered manure stockpiles were estimated according to the field measurements of a typical dairy farm in Beijing by closed chambers in four consecutive seasons. Location variation and manure removal strategy impacts were assessed on GHG emissions from the open lots. Estimated CO2, CH4 and N2O emissions from the ground level of the open lots were 137.5±64.7 kg hd-1 yr-1, 0.45±0.21 kg hd-1 yr-1 and 0.13±0.08 kg hd-1 yr-1, respectively. There were remarkable location variations of GHG emissions from different zones (cubicle zone vs. aisle zone) of the open lot. However, the emissions from the whole open lot were less affected by the locations. After manure removal, lower CH4 but higher N2O emitted from the open lot. Estimated CO2, CH4 and N2O emissions from stockpile with a stacking height of 55±12 cm were 858.9±375.8 kg hd-1 yr-1, 8.5±5.4 kg hd-1 yr-1 and 2.3±1.1 kg hd-1 yr-1, respectively. In situ storage duration, which estimated by manure volatile solid contents (VS), would affect GHG emissions from stockpiles. Much higher N2O was emitted from stockpiles in summer due to longer manure storage. Implications: This study deals with greenhouse gas (GHG) emissions from open lots and stockpiles. It’s an increasing area of concern in some livestock producing countries. The Intergovernmental Panel on Climate Change (IPCC) methodology is commonly used for estimation of national GHG emission inventories. There is a shortage of on-farm information to evaluate the accuracy of these equations and default emission factors. This work provides valuable information for improving accounting practices within China or for similar manure management practice in other countries.

Carbon dioxide and methane emissions from the scale model of open dairy lots

ABSTRACT To investigate the impacts of major factors on carbon loss via gaseous emissions, carbon dioxide (CO2) and methane (CH4) emissions from the ground of open dairy lots were tested by a scale model experiment at various air temperatures (15, 25, and 35 °C), surface velocities (0.4, 0.7, 1.0, and 1.2 m sec−1), and floor types (unpaved soil floor and brick-paved floor) in controlled laboratory conditions using the wind tunnel method. Generally, CO2 and CH4 emissions were significantly enhanced with the increase of air temperature and velocity (P < 0.05). Floor type had different effects on the CO2 and CH4 emissions, which were also affected by air temperature and soil characteristics of the floor. Although different patterns were observed on CH4 emission from the soil and brick floors at different air temperature-velocity combinations, statistical analysis showed no significant difference in CH4 emissions from different floors (P > 0.05). For CO2, similar emissions were found from the soil and brick floors at 15 and 25 °C, whereas higher rates were detected from the brick floor at 35 °C (P < 0.05). Results showed that CH4 emission from the scale model was exponentially related to CO2 flux, which might be helpful in CH4 emission estimation from manure management. Implications: Gaseous emissions from the open lots are largely dependent on outdoor climate, floor systems, and management practices, which are quite different from those indoors. This study assessed the effects of floor types and air velocities on CO2 and CH4 emissions from the open dairy lots at various temperatures by a wind tunnel. It provided some valuable information for decision-making and further studies on gaseous emissions from open lots.

Influence of deployment time and surface wind speed on the accuracy of measurements of greenhouse gas fluxes using a closed chamber method under low surface wind speed

ABSTRACT As a convenient method, the closed chamber method has been applied to determine gaseous emission fluxes from fully open animal feeding operations despite the measured fluxes being theoretically affected by deployment time, wind speed over the emitting surface and detected gas mass. This laboratory study evaluated the effects of deployment time (0 to 120 min) and external surface wind speed (ESWS) (0.00, 0.25, 0.50, 0.75, 1.00, 1.50 and 2.00 m sec-1) on the measurement accuracy of a 300 mm (diameter) × 400 mm (height) (D300×H400) closed chamber using methane (CH4), nitrous oxide (N2O) and sulfur hexafluoride (SF6) as reference gases. The results showed that the overall deviation ratio between the measured and reference CH4 fluxes ranged from 9.99 % to -37.32 % and the flux was overestimated in the first 20 min. The measured N2O and SF6 emissions were smaller than the reference fluxes using the chamber. N2O measurement accuracy decreased from -14.47 to -35.09% with deployment time extended to 120 min, while SF6 accuracy sharply increased in the first 40 min, with the deviation stabilizing at approximately -5.00%. CH4, N2O and SF6 measurements were significantly affected by deployment time and ESWS (P<0.05), and the interaction of those two factors greatly influenced CH4 and SF6 measurements (P<0.05). With the D300×H400 closed chamber, deployment times of 20 to 30 min and 10 to 20 min are recommended to measure CH4 and N2O, respectively, from the open operations of dairy farms under wind speeds lower than 2 m sec-1. Implications: This study recommended the suitable deployment times and wind speeds for using a D300 × H400 closed chamber to measure CH4, N2O, and SF6 in an open system, such as a dairy open lot and manure stockpile, to help researchers and other related industry workers get accurate data for gas emission rate. Deployment times of 20 to 30 min and 10 to 20 min were recommended to measure CH4 and N2O emissions using the D300 × H400 closed chamber, respectively, from the open operations of dairy farms under wind speeds lower than 2 m sec−1. For the measurement of SF6, a typical tracer gas, a deployment of 70 to 90 min was suggested.

Influence of Water Temperature and Spraying Interval on Cooling Effect of SprinklerSystem in Dairy Barns

Abstract. Heat stress has a detrimental effect on the health and production performance of dairy cattle. In Southeastern China, sprinkle cooling systems are widely used in dairy barns to reduce heat stress of cows. To investigate the system performance, a trial was conducted to evaluate the effect of water temperature and spraying interval on alleviating heat stress of dairy cows. Based on the parity, days in milk, and milk yield, 48 Chinese Holstein dairy cows were assigned to four groups using different treatments: 45 s spraying out of 4.75 min cycle (SIa) or 6.75 min cycle (SIb) by using water from a tank with thermal insulation (TI) or without thermal insulation (NTI). The trial was carried out for two 7-day periods using a nested design. The results showed that water temperature was 2.8°C lower for the TI tank than the NTI tank. No differences were observed between the TI and NTI groups in terms of rectal, udder, abdomen, and back temperatures of the cows. Respiration rate and vulva temperature of the cows were lower for TI compared with NTI. Udder, abdomen, and back temperatures were lower for SIb compared with SIa in both TI and NTI group. Vulva temperature and respiration rate were lower for SIb compared with SIa in TI group. Serum concentration of K was higher but Ca and growth hormone were lower for TI compared with NTI. Serum cortisol concentrations were higher for SIa compared with SIb in both TI and NTI groups. Results of the study showed that the cooling effect of the spraying system could be improved in lactating dairy cows by adding thermal insulation for the water tank and reducing the spraying interval.

Water temperature and spraying interval may affect the cooling effect of the sprinkler system in dairy farm

Abstract. Heat stress has a detrimental effect on the health and production performance of dairy cow. To alleviate the heat stress, sprinkle cooling system is widely used in the dairy barns in Eastern and Southern China, where is characterized by a hot and humid climate in summer. Due to a lack of systemic design and study, the cooling effect usually could not reach the targeted goals and the animals suffer a severe stress. In order to improve the system performance, this study was conducted to test the effect of spraying interval (SI) and water temperature (WT) on alleviating the heat stress of dairy cows. Based on the parity, day in milk, and milk yield, 48 Chinese Holstein dairy cows were assigned into four groups with different treatments: Thermal insulation a (TIa), Thermal insulation b (TIb), Non thermal insulation a (NTIa) and Non thermal insulation b (NTIb). In period 1, a 4-min SI was used for TIa and NTIa, and a 6-min SI was used for (TIb) and (NTIb). After a 3-day transition, the 4-min SI was exchanged with the 6-min one. The results showed that spraying water temperature of TI groups was 2.8 oC lower. The rectal temperature of TIa group cows was about 0.2 oC lower than that of cows in the other three treatments, and its vulva temperature was lower as well. Respiration rates of the cows in TIb and NTIb groups were 79.5 and 92.8 per min, respectively, and the TIb group was significantly lower. Comparing NTI group, the Blood serum potassium of the TIa group was much higher (P TI = 0.003). Blood serum calcium contents of dairy cows in the TI groups were decreased (P TI = 0.036). Cortisol in cows of TIa group was higher than that of TIb and NTIb groups (P = 0.039). TI group had a lower growth hormone (GH) than NTI group (P = 0.049). This research shows the cooling effect of the spraying system could be improved by adding thermal insulation on the water tank and decreasing the SI, which does not greatly alter concentrations of metabolic hormones in lactating dairy cows.

Measurement of Greenhouse gas Emission from Naturally Ventilated Dairy Cattle Buildings

Field measurements were carried out for 11 naturally ventilated dairy cattle buildings with different floor types and manure handling systems in Denmark and China. Inside and outside CO2, CH4 and N2O concentrations were continuously measured at the representative locations of the buildings. Based on the estimation of CO2 production of the housed animals, a CO2 mass balance method was used to determine air exchange rate of the naturally ventilated buildings. During the measurement period, the overall CH4 emission rate from the dairy cattle buildings was averaged 246 g HPU-1 d-1 with a standard deviation of 44.6 g HPU-1 d-1, largely changing within the range of 200 to 300 g HPU-1 d-1. The overall mean emission rate of N2O from the investigated buildings was approximately 1.6±0.26 g HPU-1 d-1. The results indicated that CH4 emission rates did not vary greatly for the measurements, and its emission was not affected by floor types or ambient temperatures. Large variations in N2O emission rates were not observed in similar buildings. Significant differences were found on CH4 and N2O emissions from the dairy buildings in Denmark and China, which might because of the difference in cow’s production levels.

Improving air exchange rate calculations by using carbon dioxide balance method and estimating ammonia emissions from natural ventilated dairy buildings.

Determination of air exchange rates plays a key role in estimating ammonia and other contaminated gas emissions from animal buildings. The objectives of this study was to evaluate the effect of cows’ body weight and the production level on the accuracy of air exchange rate calculation from naturally ventilated dairy cow buildings; and to estimate ammonia emission rates using the improved air exchange rate from typical dairy housing in China. Field measurements were carried out in two naturally ventilated dairy cow buildings with different floor types. The production information of each cow was inputted to the CIGR model to calculate the cows’ heat generation and hence to estimate the CO2 production. And then the air exchange rates of the buildings were calculated by using the mass balance method. Comparing with the calculation value by using the simplified method, the total heat production was 17.45% and 8.22% higher for the solid concrete floor and slatted floor individually when considering the production information of dairy cow. The mean ammonia emission rate was 22.66±2.74 g d-1 cow-1 and 10.12±1.91 g d-1 cow-1 for the slatted floor building and solid concrete floor building individually during the measurement. The ammonia concentration was 50% higher for slatted floor building compared with the solid concrete floor building. The results indicated that the individual cow weight and pregnant days should be considered in estimating the air exchange rate using CO2 balance method from naturally ventilated animal housing, especially for the dairy cow of late pregnancy. Otherwise, ammonia emission rate would be underestimated.

Evaluating effectiveness of spraying systems to reduce heat stress on dairy cows

The objectives of the paper are to select appropriate type of nozzle for a spraying system which generates large water droplets and to evaluate its cooling effects on heat-stress prevention of dairy cattle. The nozzles were installed at five different angles (45o, 0o, -45o, -90o, -135o), and tested with three different incoming water pressures (0.10 Mpa, 0.15 Mpa, 0.20 Mpa). The results showed that refraction nozzle installed at -135° were the most efficient. After screening out the spraying nozzles, a field experiment was conducted in a commercial dairy farm in summer to test the cooling effect of the modified spraying system by monitoring and evaluating the ambient temperature, thermal humidity index (THI) and physiological index of the cows. For the field, ambient temperature and THI inside the dairy cattle shelters installed with the spraying systems were significantly decreased during the experimental period. The ambient temperature was averagely lowered by 2.0°C in treatment group, with an average value of 26.9±0.20°C. The surface temperatures of the frontal shoulder and udder, rectal temperature and respiratory rate of the cows in the treatment group were 2.3°C, 2.1°C, 0.6°C and 18 times min-1 lower than those of the control group, respectively. The milk production of cows in treatment group was 4% higher than that of the control group.

Characterization of Two Types of Covered Creep Boxes for Piglet Usage and Piglet Performance in a Naturally Ventilated Swine Farrowing Building

This study investigates two types of covered piglet creep boxes in a naturally ventilated swine farrowing building with regards to air quality (ammonia and carbon dioxide levels), piglet usage of the box, and piglet health and performance. The covered creep boxes featured either double plastic curtains along the entire width of the box (designated as the DC box) or an arc-shaped access opening occupying about one-third of the box width (designated as the AO box). The study was conducted with 12 farrowing crates, six per box regimen, during wintertime. Continuous, 24-h video observations of the piglet behaviors were made at days 2, 9, and 16 of post-parturition. Ammonia and CO2 concentrations inside the creep boxes were measured using portable electronic sensors. The results showed that the interior NH3 levels tended to be lower for the DC type than for the AO type, although the magnitude was quite low in both cases (averaging 4 to 6 ppm). No significant difference was found in the interior CO2 concentrations between the two box types. Pre-weaning piglet culling rate (mean±S.D.) was 2.5±0.08% and 11.3±1.17% for the DC and AO litters, respectively (p < 0.001). Although there was no significant treatment effect (p = 0.26), piglet diarrhea morbidity was numerically lower for the DC litters (0.80±0.03%) than for the AO litters (1.29±0.12%). At 21-d weaning age, the DC litters showed heavier body weight (6.18±0.23 kg) than the AO litters (5.69±0.18 kg) (p < 0.05). Results of the present work, despite the relatively small sample size, indicate that the DC-style covered creep box seems more conducive to enhancing piglet usage of the box and piglet health and performance.