Association between limb conformation and retention of sows through the second parity

Objective evaluation of female feet and leg joint conformation at time of selection and post first parity in swine1

Feet and legs of replacement females were objectively evaluated at selection, i.e., approximately 150 d of age (n = 319) and post first parity, i.e., any time after weaning of first litter and before second parturition (n = 277) to 1) compare feet and leg joint angle ranges between selection and post first parity; 2) identify feet and leg joint angle differences between selection and first 3 wk of second gestation; 3) identify feet and leg joint angle differences between farms and gestation days during second gestation; and 4) obtain genetic variance components for conformation angles for the two time points measured. Angles for carpal joint (knee), metacarpophalangeal joint (front pastern), metatarsophalangeal joint (rear pastern), tarsal joint (hock), and rear stance were measured using image analysis software. Between selection and post first parity, significant differences were observed for all joints measured (P < 0.05). Knee, front and rear pastern angles were less (more flexion), and hock angles were greater (less flexion) as age progressed (P < 0.05), while the rear stance pattern was less (feet further under center) at selection than post first parity (only including measures during first 3 wk of second gestation). Only using post first parity leg conformation information, farm was a significant source of variation for front and rear pasterns and rear stance angle measurements (P < 0.05). Knee angle was less (more flexion; P < 0.05) as gestation age progressed. Heritability estimates were low to moderate (0.04-0.35) for all traits measured across time points. Genetic correlations between the same joints at different time points were high (>0.8) between the front leg joints and low (<0.2) between the rear leg joints. High genetic correlations between time points indicate that the trait can be considered the same at either time point, and low genetic correlations indicate that the trait at different time points should be considered as two separate traits. Minimal change in the front leg suggests conformation traits that remain between selection and post first parity, while larger changes in rear leg indicate that rear leg conformation traits should be evaluated at multiple time periods.

Measuring the efficacy of flunixin meglumine and meloxicam for lame sows using a GAITFour pressure mat and an embedded microcomputer-based force plate system

Pain associated with lameness on farm is a negative affective state and has a detrimental impact on individual farm animal welfare. Animal pain can be managed utilizing husbandry tools and through pharmacological approaches. Nonsteroidal anti-inflammatory drugs including meloxicam and flunixin meglumine are compounds used in many species for pain management because they are easy to administer, long lasting, and cost-effective. Assessing an animal's biomechanical parameters using such tools as the embedded microcomputer-based force plate system and GAITFour pressure mat gait analysis walkway system provides an objective, sensitive, and precise means to detect animals in lame states. The objectives of this study were to determine the efficacy of meloxicam and flunixin meglumine for pain mitigation in lame sows using the embedded microcomputer-based force plate system and GAITFour pressure mat gait analysis walkway system. Lameness was induced in 24 mature mixed-parity sows using a chemical synovitis model and compared 3 treatments: meloxicam (1.0 mg/kg per os), flunixin meglumine (2.2 mg/kg intramuscular) and sterile saline (intramuscular). Weight distribution (kg) for each foot was collected twice per second for a total of 5 min for each time point using the embedded microcomputer-based force plate system. Stride time, stride length, maximum pressure, activated sensors, and stance time were collected using 3 quality walks (readings) for each time point using the GAITFour pressure mat gait analysis walkway system. Sows administered flunixin meglumine or meloxicam tolerated more weight on their lame leg compared with saline sows (P < 0.005). Sows administered flunixin meglumine or meloxicam had smaller differences in stance time, maximum pressure, and activated sensors between the sound and lame legs compared with saline-treated sows between 37 and 60 h after lameness induction (P < 0.03). In conclusion, flunixin meglumine and meloxicam administration mitigated pain sensitivity in sows after lameness induction when pain sensitivity was evaluated with the embedded microcomputer-based force plate system and GAITFour pressure mat gait analysis walkway system. Analgesic drugs may be a key tool to manage negative pain affective states associated with lameness.

Culling intervals and culling risks in four stages of the reproductive life of first service and reserviced female pigs in commercial herds

The objectives of this study were to measure culling intervals and culling risks in the four stages of the reproductive life of female pigs and to compare culling intervals between the number of services and between herd groups, based on herd productivity. We also compared survival patterns of females pigs between these herd groups. Our data set included lifetime records of 52,792 females born between 2001 and 2004 in 101 commercial herds. Two herd groups were selected on the basis of the upper 25th percentile of pigs weaned per mated female per 5 yr between 2002 and 2006, namely the high-performing herds, and ordinary herds. Culled females were also allocated into four groups based on the stages of their reproductive life when culled: unmated gilts, mated gilts, unmated sows, and mated sows. Culling intervals in unmated gilts and mated gilts were defined as the number of days from birth to culling and from first mating to culling, respectively. Culling intervals in unmated sows and mated sows were the number of days from weaning to culling. The number of services was categorized into two groups: first service and reservice groups. Multilevel linear mixed-effects models and survival analysis were performed. Culling intervals (+/-SEM) in unmated gilts, mated gilts, unmated sows, and mated sows were 302.9+/-1.16, 98.4+/-0.92, 14.3+/-0.12, and 89.6+/-0.42 d, respectively. Culling risks in the four groups were 5.6%, 7.1%, 58.0%, and 29.3%, respectively. In unmated gilts, mated gilts, and mated sows, the culling intervals in the high-performing herds were 43.0, 18.9, and 16.0 d shorter than those in ordinary herds, respectively (P<0.05), but no difference was found between the herd groups for the culling interval of unmated sows. For mated sows in the reservice group, culling intervals of high-performing herds were >or=13.7 d shorter than those of the ordinary herds (P<0.05), but for mated sows in the first service group, there was no difference in the culling interval between the herd groups. The culling hazard from 8 wk postweaning for mated sows in high-performing herds increased more rapidly than that in ordinary herds. In conclusion, to reduce culling intervals and improve herd productivity, we recommend implementing a strict culling policy for mated gilts and mated sows, especially reserviced females.

Longevity and efficiency associated with age structures of female pigs and herd management in commercial breeding herds

Annual performance measurements, age structures of female pig inventories, and by-parity culling rates were abstracted from data files of 110 herds that participated in a data-share program in Japan. Parity at culling was used as a prime measurement of longevity, whereas pigs weaned x mated female(-1) x year(-1) (PWMFY) was a prime measurement of reproductive efficiency. High or low longevity herds were based on the greatest 50% of the herds or the remaining herds ranked by parity at culling, whereas high or low reproductive efficiency herds were grouped according to the greatest 50% of the herds or the remaining herds ranked by PWMFY. Measurements were analyzed as a 2 x 2 factorial arrangement, using the main effects of the 2 herd groups of longevity (high or low) and reproductive efficiency (high or low). Means of parity at culling and PWMFY were 4.6 (SD = 0.82) and 21.2 (SD = 3.02), respectively. The high longevity group had 1.27 greater parities at culling than the low longevity group (P < 0.05), but no differences between the high and low longevity groups were found in PWMFY (P = 0.21). No differences between the high and low efficiency groups were found in parity at culling (P = 0.50). No interactions between the longevity and efficiency groups were found on any longevity or efficiency measurement (P > 0.20). In herd management, the percentage of reserviced females and the percentage of multiple matings were associated with the longevity group and the efficiency group (P < 0.05). The high longevity group had lower culling rates in parity 0 to 6 than the low longevity group (P < 0.05), whereas no differences between the low and high efficiency groups were found in culling rates in parity 0 to 2 (P > 0.20). This study suggests that measures to achieve longevity and high reproductive efficiency in breeding herds do not conflict and that high reproductive efficiency and high longevity can be achieved.