Plasma Cortisol and Behaviour in Early Weaned Piglets

Comparisons were made of Cortisol concentration and behavioural activity between piglets weaned at 3 weeks of age (early weaned piglets), and piglets weaned at 8 weeks of age (control piglets). Early weaned littermates were placed in cages with a floor area of either 0.20 m² per piglet or 0.15 m² per piglet. At 8 weeks of age, the piglets in the control litters were moved from the sow and early weaned piglets were moved from the cages. All litters were placed in pens, 1 pen for each litter. Radioimmunoassay was used for plasma Cortisol determination. Behavioural activity included determination of play, aggressive behaviour and non-nutritive oral activity. Statistical analysis for possible association between plasma Cortisol concentration and age, housing conditions, litter and sequence of capture of littermates for blood collection revealed a complex pattern. Generally, higher plasma Cortisol concentrations and more aggressive and non-nutritive oral activity, but less playing activity, were associated with early weaning. Plasma Cortisol concentration in individual piglets was positively correlated to both aggressive and non-nutritive oral behaviour, but was negatively correlated to playing behaviour. It is concluded that early weaning is a stressor.     

3周龄与6周龄断奶仔猪生产性能的比较

选9窝约长北3元杂交仔猪(116头)随机分成3组、第1、2组3周龄断奶,分别饲喂试验日粮和代乳料日粮。第3组6周龄断奶作为对照。6周龄到20公斤体重阶段饲喂同一营养水平的仔猪料,以比较3者的生产性能。试验结果表明:21—42日龄阶段,由于断奶应激,试验组日增重(ADG)明显低于对照组。42日龄以后至达20公斤体重阶段试验组的日增 重与对照组和代乳料组已无明显差异。早期断奶仔猪在度过断奶应激后,有补偿生长反应。     

日粮纤维素水平及饲养环境对断奶猪生长性能、养分消化及肠道健康的影响

文章旨在评估日粮添加不同水平的纤维素及不同饲养环境对断奶仔猪生长性能、营养物质表观消化率及小肠绒毛形态的影响.试验将1296头24?d断奶、平均体重无显著差异的仔猪随机分为4组,每组324头,每组6个重复(54头/重复).将T1和T2组断奶仔猪饲养在环境条件良好的圈舍中,在断奶后前2周分别饲喂纤维素水平为0％和2％的日...     

断奶日龄对五指山仔猪生长性能和血清生化指标的影响

本试验旨在研究断奶日龄对五指山仔猪生长性能和血清生化指标的影响。选取日龄相近(±1 d)、体重[(0.56±0.07)kg]相近的五指山仔猪96头,随机分成4组,每组设4个重复,每个重复6头猪。4组仔猪分别在21、28、35和42日龄断奶。试验从8日龄开始,至56日龄结束,试验期间定期测定体重、采食量和血清生化指标。结果表明:各组仔猪断奶后平均日增重(ADG)出现不同程度的下降,且断奶日龄越早,ADG下降幅度越大;35日龄断奶组和42日龄断奶组21~28日龄、28~35日龄、35~42日龄、49~56日龄阶段的ADG显著高于21日龄断奶组(P0.05)。各组仔猪断奶后平均日采食量(ADFI)显著增加(P0.05),42日龄以后,各组ADFI无显著差异(P0.05)。21日龄断奶组、28日龄断奶组、35日龄断奶组血清总蛋白(TP)、白蛋白(ALB)、免疫球蛋白G(IgG)、免疫球蛋白M(IgM)含量以及谷丙转氨酶(ALT)、谷草转氨酶(AST)、乳酸脱氢酶(LDH)活性在断奶后7 d均发生显著变化(P0.05),并以21日龄断奶组波动最大;与35日龄断奶组和42日龄断奶组相比,21日龄断奶组28、35日龄时血清TP、ALB、IgG、IgM含量显著降低(P0.05),ALT、AST、LDH活性显著提高(P0.05),到56日龄时,血清TP、IgG、IgM含量仍显著低于35日龄断奶组和42日龄断奶组(P0.05)。21日龄断奶组血清甘油三酯(TG)、胆固醇(CHOL)含量在28~56日龄间存在显著变化(P0.05),35日龄断奶组和42日龄断奶组血清TG、CHOL含量在整个试验期内均无显著变化(P0.05)。35日龄断奶组血清TP、ALB、IgG、IgM含量以及ALT、AST、LDH活性除在42日龄时与42日龄断奶组存在显著差异(P0.05)外,其余时间点与42日龄断奶组均无显著差异(P0.05)。由此得出,35或42日龄断奶的五指山仔猪在生长性能、血清生化指标及免疫机能方面优于21日龄断奶的五指山仔猪。     

改善早期断奶仔猪肠道健康和功能的营养策略研究进展

商业化生产中仔猪早期断奶（3~4周龄）恰是肠道功能发育的关键时期,断奶应激带来的持续性肠道屏障功能损伤是断奶仔猪细菌性和病毒性肠炎及断奶后腹泻的主要诱因。饲料端“禁抗”背景下,运用营养策略改善早期断奶仔猪肠道功能的研究是研究者关注的焦点问题。从早期断奶对仔猪肠道屏障功能的影响及多种营养策略对断奶仔猪肠道功能改善的作用,综述了早期断奶致仔猪肠道屏障功能损伤的机理及氨基酸、抗菌肽、益生菌、膳食纤维、低聚糖、有机酸、微量营养素和脂质营养等营养策略改善仔猪肠道功能的作用机制,为通过营养策略改善断奶仔猪肠道功能相关研究提供参考。     

Growth in weaned piglets and levels of iodothyronines in the blood during the administration of thyroactive substances

In five trials with 100 piglets we studied the effects of thyreoglobulin, potassium nitrite and the thyreostatic preparation Carbimazol, which were added to a complete starter in the period from early weaning to the age of four weeks. Changes in the concentrations of thyroxine (T4) and triiodothyronine (T3) in the blood serum of control unmedicated piglets weaned from the sows can be characterized, after a short rise, by a decrease which stopped usually in the fourth week, accompanied by higher body weight gains. The lowest drop of T4 level was recorded in the group given potassium nitrite, with 21% methemoglobin, having the highest actual and relative weight gains. The T4 and T3 levels were not influenced by thyreoglobulin. They were decreased by Carbimazol by more than two thirds of the values which were usual at weaning if Carbimazol was administered at the highest rate of 60 mg per 1 kg of feed; neither was the growth of body weight nor feed consumption per unit of weight gain negatively influenced. An application of thyreotropic hormone on the 14th day after weaning demonstrated an inhibition of iodothyronine secretion in piglets which had been given Carbimazol, and a good response in control piglets. We drew a conclusion that the decrease in T4 and T3 levels after early weaning did not occur when iodothyronine intake with mother milk was interrupted nor was it caused by iodine deficiency, nor was it a primary cause of the reduced growth rate of piglets.     

The effect of heated mash on performance and feeding behavior of newly weaned piglets

The influence of heated mash on growth and feeding behavior of newly weaned piglets was investigated. An automatically ventilated nursery with 4 identical pens was used. Twenty piglets weaned at 21 d were housed in each pen. The experiment was repeated 3 times. In total, data were obtained from 240 piglets of 12 pens. The pens were provided with a sensor-controlled, automatic feeding device, which dosed a ready-mixed mash in a trough. In each of 2 of the pens, the feed was mixed with warm water at 36 degrees C, during the first week of weaning. This heated mash had a temperature of 34 degrees C at the outlet of the automatic feeding device (experimental group). In the 2 control groups, the water was not heated and the temperature of the mash was 14 degrees C at the outlet of the automatic feeding device. From the second week of weaning, the mash had a temperature of 14 degrees C at the outlet of the automatic feeding device in all 4 pens. Piglets were weighed at weaning, at weekly intervals through 49 d after weaning, and on d 139 after weaning. Behavior of the whole group, as well as behavior of selected focal animals, was evaluated for the first 48 h after weaning. In addition, skin condition of piglets was assessed on day of weaning and on d 7, 14, and 21 after weaning. The amount of feed consumed by the piglets was recorded on a daily basis throughout the whole period of nursery. Over the total period of the study, piglets in the experimental group gained 3.98 +/- 1.66 kg (P = 0.047) more than the control group. The difference was particularly clear during the nursery period (49 d) when the experimental group gained 0.89 +/- 0.23 kg more than the control group (P = 0.03). Although piglets in the control group consumed 37.15 +/- 0.15 kg of feed over the complete nursery period, the experimental group consumed 42.56 +/- 0.15 kg per piglet (P = 0.023). By heating the mash feed in the first week after weaning, both growth performance as well as feed consumption of piglets could be increased. No difference in feed conversion and feeding behavior was found between groups.     

Immune responses of piglets to weaning stress: impacts of photoperiod

An acute stress response can be provoked by abrupt social, nutritional, and environmental changes associated with weaning, and this may disrupt homeostasis and thus compromise well-being. Manipulating environmental factors, such as photoperiod, might provide a simple way to reduce the physiological consequences that piglets experience due to weaning stress. The objective of this study was to evaluate the impacts of photoperiod manipulation across various weaning ages on leukocyte populations, lymphocyte proliferation, natural killer cytotoxicity (NK), chemotaxis, phagocytosis, and immunoglobulin G, cortisol, and BW of piglets during the nursery phase. Sixty-eight crossbred piglets were obtained from sows kept on a short-day (8 h of light/d) photoperiod from d 90 of gestation until weaning. Piglets were weaned at 14, 21, or 28 d of age and kept on a short or long (16 h of light/d) photoperiod until 10 wk of age. Piglet BW and blood samples were collected at weaning and at 6, 8, and 10 wk of age. Pigs weaned at 28 d had reduced neutrophil counts (P < 0.001), phagocytosis (P < 0.001), and lymphocyte proliferation (P < 0.05) at weaning compared with those weaned at 14 and 21 d. Pigs weaned at 21 d tended to have lower (P = 0.08) lymphocyte counts than did pigs weaned at 14 or 28 d. Pigs weaned at 14 d had reduced (P < 0.01) NK relative to those weaned at 21 or 28 d. Photoperiod also influenced pig BW and immune status. Generally, those pigs on the long-day photoperiod and weaned at 28 d were heavier (P < 0.001) than their counterparts weaned at 14 or 21 d. At 6 wk of age, NK was greater (P = 0.002) in pigs kept on a long day and weaned at 14 or 21 d than in pigs weaned at 28 d. Phagocytosis was less (P = 0.005) at 6 wk of age, but was greater at 8 wk, in piglets kept on the long day and weaned at 28 d than in long-day pigs weaned at 14 or 21 d. These results suggest that photoperiod differentially influences immune responses in piglets weaned at different ages and indicate an inverse relationship between growth and immune status. Here, weaning at 28 d and a long-day photoperiod was the treatment combination that was most physiologically beneficial to piglets, whereas a 14-d weaning and short-day photoperiod was least physiologically beneficial.     

Temporal changes in carbohydrate digestive capacity and growth rate of piglets in response to glucocorticoid administration and weaning age

Two experiments were conducted that demonstrated that a single injection of hydrocortisone 21-acetate (HYD, 25 mg/kg BW) administered to 6-d-old nursing piglets resulted in a twofold elevation (P less than .02) of pancreatic amylase within 2 d; activity was unaffected by an injection of 15 IU adrenocorticotropic hormone (ACTH)/kg BW (P greater than .20). Intestinal sucrase and maltase activity tended to be elevated (P less than .20) 2 and 4 d postinjection with HYD but returned to normal (uninjected) levels by 14 d of age. The normal decline of intestinal lactase activity was delayed by at least 4 d in response to both hormones (P less than .10). Organ weights were not affected by either hormone. In a separate experiment, postweaning mortality was reduced (12 vs 27%) and growth rate was substantially improved by administration of HYD to piglets 4 and 2 d prior to weaning at 14 d of age. Hydrocortisone resulted in a faster rate of gain the 1st wk postweaning for pigs weaned at 21 or 28 d. Subsequent gain by control and HYD piglets weaned on d 21 was similar, but HYD subsequently impaired growth rate of piglets weaned at 28 d of age. Growth rates of control and ACTH piglets were similar at each postweaning period regardless of weaning age (weaning age [lin.] x week postweaning [quad.] x treatment, P less than .07). This differential treatment response of daily gain may be due in part to effects on feed intake (weaning age [lin.] x week postweaning [lin.] x treatment, P less than .10). We conclude that a single injection of HYD to 6-d-old piglets precociously induces pancreatic amylase and that the sensitivity of piglets to HYD is age-dependent.     

断奶仔猪的生理特点及乳酸杆菌在断奶仔猪中应用的研究进展

仔猪早期断奶在提高母猪利用率的同时也带来了其生长性能和抗病力的下降,因此早期断奶仔猪的健康生长在养猪业发展中具有重要意义。本文对早期断奶仔猪的生理特点和乳酸杆菌在断奶仔猪中的应用效果进行了综述。     

碎米替代玉米对断奶仔猪生长性能、血清生化及蛋白质代谢的影响

文章旨在研究日粮用碎米完全替代玉米对断奶仔猪生长性能、血清生化及蛋白质代谢的影响.试验将180头21?d断奶、平均体重为(6.48±0.04)kg的仔猪随机分为2组,每组5个重复,每个重复18头.两组断奶仔猪分别饲喂以45％玉米和碎米为主的日粮,试验共持续14?d.结果:与玉米组相比,碎米组仔猪断奶后8～14?d平均日...     

Effect of Early Weaning,Split-Weaning and Nursery Feeding Programmes on the Growth of Landrace×Desi Pigs

An experiment using 164 crossbred pigs born to 20 first-parity sows was conducted to evaluate the growth performance of piglets in four weaning management regimens: T1, conventional weaning at 56 days; T2, early weaning at 28 days; T3, split-weaning of the heavier half of the litter at day 28, the remaining half being weaned at 56 days; and T4, split-weaning of the lighter half of the litter at 28 days, with the animals kept on a special nutrient diet up to 56 days, and the heavier half being weaned at 56 days. Split-weaning of the lighter half in combination with feeding a special nutrient diet resulted in an increase of average daily gain of 21% from day 28 to day 140 compared to conventional weaning and of 36% compared to early weaning at day 28. Compared to the control (T1), the average weights of piglets at the 140th day in groups T4 and T3 were 19.6% and 6.16%, respectively, higher, whereas that of the T2 was 8% lower. It is concluded that feeding a special nutrient diet to lighter pigs is beneficial in overcoming the post-weaning lag and enables maximal weight gain.     

益生性活性卵白制剂对早期断奶仔猪生产性能和肠道pH的影响

试验选取28日龄断奶的三元[杜×（大×长）]杂交仔猪36头,平均初始体重为5.22±0.89 kg,随机分为活性卵白试验组和对照组,每个处理组3个重复,每个重复6头。对照组饲喂基础日粮,活性卵白试验组在相同的基础日粮基础上口服饲喂活性卵白制剂,剂量为10 ml/d·只,连续服用10 d（断奶前5 d至断奶后5 d）,研究添加服用益生性活性卵白制剂对断奶仔猪生产性能、腹泻率和肠道各段pH的影响。结果表明,活性卵白物质可显著提高断奶仔猪的日增重、日采食量,显著改善仔猪生长性能,具有更好的提高断奶仔猪生长速率的趋势及较好的阶段增重优势。在预防仔猪消化道疾病方面活性卵白制剂具有良好效果,可提高断奶仔猪的存活率,腹泻率下降幅度较大,对缓解腹泻的作用明显优于对照组。因此,早期断奶仔猪口服活性卵白制剂有助于提高其生产性能,降低腹泻率,具有降低仔猪肠道内容物pH的趋势。     

Water consumption in piglets weaned early at various ages and fed a liquid diet]

Water consumption was recorded in 72 piglets of the Lorge White breed, weaned either on the second, sixth, tenth day or on the fourteenth day of age, this parameter was followed till the age of four weeks. The piglets were kept individually in a thermoneutral zone and they received a milk diet with macronutrient content, similar to sow's milk and water content of from 78.47%. The diet was offered to suck nine times a day in two-hour intervals. The piglet age at weaning was found to influence significantly water intake. Daily water ingestion is higher in piglets separated from the sows at a younger age than in piglets weaned later on; it reaches as much as 29% in the first group, 26% in the second group, 28% and 20% of live weight in the third and fourth groups, respectively. If converted to the metabolic weight, the percentage is still higher: more than 40% in the first group at the end of the fourth week. Although the spans of weaning beginnings were always identical in particular groups of piglets (four days), the differences in the water consumption were not the same. The differences were smaller between the first and second group, and the third and fourth group, in comparison with those between the second and third group. This fact confirms previous general statements about the periodization of early postnatal life of piglets. The beginning of weaning of the first two groups belongs to the "suckling" period, while the beginning of weaning of the other groups is within the "weaning" period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of weaning age on the villous height and disaccharidase activities in the porcine small intestine

Body weight gain after weaning is correlated with villous height and disaccharidase activity. This evidence suggests that the maintenance of the small intestinal structure and function after weaning is important for the growth of piglets. We demonstrated that the influence of weaning age was obtained by disaccharidase activities and villous height in eight sections of the porcine small intestine. Therefore, we designed three weaning ages (weaned at the ages of 14, 21 or 28 days) and the piglets were slaughtered after 7 or 14 days post‐weaning. The remaining suckling piglets were slaughtered at the age of 1, 7, 14, 21 and 28 days. Four piglets were slaughtered at each event; therefore, 44 piglets were used in this study. Villous height and disaccharidase activities were measured in each section of the small intestine. Early weaning such as that at 14 days had severe influence on villous and disaccharidase activities. In particular, weaning of 14‐day‐olds did not result in maltase activity at least 2 weeks post‐weaning. Accordingly, the weaning age of crossbred piglets is recommended to be at least 21 days or more on the basis of villous height and disaccharidase activity analyses.     

Beef heifer development within three calving systems

A 3-yr study was conducted to evaluate the effects of calving system, weaning age, and postweaning management on growth and reproduction in beef heifers. Heifer calves (n = 676) born in late winter (average birth date = February 7 +/- 9 d) or early spring (average birth date April 3 +/- 10 d) were weaned at 190 or 240 d of age, and heifers born in late spring (average birth date May 29 +/- 10 d) were weaned at 140 or 190 d of age. Heifers were managed to be first exposed to breeding at approximately 14 mo of age. After weaning, the calves were randomly assigned to treatments. Heifers on the constant gain treatment were fed a corn silage- and hay-based diet. Heifers on delayed gain treatments were placed on pasture but were fed grass hay or a supplement, or both, depending on the forage conditions. Three months before their respective breeding seasons, delayed gain heifers were moved to drylot and fed a corn silage- and barley-based diet (late winter or early spring) or moved to spring rangeland (late spring). The data were analyzed using mixed model procedures with calving system, weaning age, and postweaning management options creating 12 treatments. Average daily gain was 0.36 +/- 0.05 (SED) kg/d less (P < 0.001) for delayed gain heifers during the initial phase, whereas these heifers gained 0.44 +/- 0.03 kg/d more (P < 0.001) than constant gain heifers during the last 90 d before breeding. Body weights at the beginning of the breeding season did not differ (P = 0.97) between constant gain and delayed gain heifers but were affected by calving system and weaning age, reflecting some of the differences in initial BW. Prebreeding BW for heifers weaned at 190 d of age were 36 +/- 6.4 kg heavier (P < 0.001) for those born in late winter and early spring compared with late spring and were 388, 372, and 330 kg for heifers weaned in October at 240, 190, or 140 d of age (linear effect, P < 0.001). The proportion of heifers exhibiting luteal activity at the beginning of the breeding season was not affected (P = 0.57) by treatment. Approximately half of the heifers were randomly selected for breeding. Treatment had no effect (P = 0.64) on pregnancy rates. In conclusion, heifers from varied calving systems and weaning strategies can be raised to breeding using either constant or delayed gain strategies without affecting the percentage of heifers cycling at the beginning of the breeding season. These results suggest that producers have multiple options for management of heifer calves within differing calving systems.     

断奶日龄对仔猪心肌、背最长肌和半腱肌抗氧化功能的影响

为研究不同断奶日龄对仔猪心肌、背最长肌和半腱肌抗氧化功能的影响,试验选取受试仔猪24头,随机分为4个处理,每个处理6个重复,每个重复1头仔猪,各处理仔猪分别在14日龄、21日龄、28日龄和35日龄断奶,所有仔猪在42日龄宰杀取样.测定仔猪相应组织的MDA含量和抗氧化酶活性.结果表明,随着断奶日龄的推迟,仔猪心肌、背最长肌和半腱肌中MDA含量逐渐降低,35日龄断奶组仔猪心肌MDA含量显著低于14日龄组（P＜0.05）,28日龄和35日龄断奶组背最长肌和半腱肌MDA含量显著低于14日龄组（P＜0.05）;与28日龄和35日龄断奶组相比,14日龄断奶组心肌T-SOD、GSH-Px活性（P＜0.05）以及半腱肌GSH-Px活性均显著降低（P＜0.05）,各断奶日龄组仔猪背最长肌抗氧化酶活性无显著差异.以上结果提示,仔猪断奶日龄越早,其肌肉组织脂质过氧化反应越强,抗氧化功能越低.     

Can outdoor rearing and increased weaning age compensate for the removal of in-feed antibiotic growth promoters and zinc oxide?

This experiment determined whether delayed weaning and outdoor rearing could compensate for the removal of antimicrobials from piglet diets. One hundred and sixty litters of Large White (75%) × Landrace (25%) pigs on the same unit were reared either indoors (In) or outdoors (Out) and weaned at either 4 or 6 weeks of age into flat deck accommodation onto diets supplemented with either no antibiotic growth promoters and no zinc oxide (Un) or 40 mg avilamycin and 3.1 g zinc oxide/kg diet (S). Piglet performance was monitored to 8 weeks of age. A proportion of litters (25%) were sampled to investigate the effect of the different treatments on gut development. Mortality was higher in the first 24 h of life for Out piglets which subsequently grew faster to weaning. This was not simply due to smaller litter size as total litter gain was higher in outdoor litters. All piglets responded positively to antimicrobial supplementation post weaning regardless of rearing environment and weaning age and this was the biggest influence on post weaning performance. Outdoor piglets grew faster than indoor piglets post weaning (295 versus 242 ± 8.6 g/pig/day for the first 2 weeks post weaning, P < 0.001) and over the same period 6 week weaned piglets grew faster than 4 week weaned (324 versus 213 ± 8.6 g/pig/day, P < 0.001), however, when compared at similar age, 6 week weaning was detrimental to piglet growth with average daily gain (adg) from 4 to 8 weeks of age 310 g/pig/day versus 329 for 4 week weaned piglets (P = 0.001). At 8 weeks of age the outdoor 6 week weaned unsupplemented piglets had similar average weight to the indoor 4 week weaned supplemented piglets indicating the potential of this combination to counteract the need for antimicrobials, however the benefit was due to enhanced weaning weight not to improved post weaning performance.     

后期饲养战略对于早期断奶牛生产速度的影响

[目的]为探索适宜当地的犊牛早期断奶时间,促进犊牛早期生长发育和使母牛尽快恢复体况,进入下一个繁殖周期。[方法]选择体格大小一致、健康无疾病、体重接近,父本相同,3月龄西杂犊牛20头作为试验牛,随机分成A组和B组,每组10头(公、母数量相同)。A组经过1个月断奶精料、粗料和多汁饲料的过渡性适应,4月龄断奶,并根据犊牛生长发育逐渐增加精料、多汁饲料,B组按照养殖场饲喂方法饲养,并于6月龄断奶,A组与B组犊牛6月龄断奶后自由采食粗饲料、按体重1%饲喂精饲料,分别在犊牛6,12,18月龄称重。[结果]结果表明:肉牛18月龄时A、B组犊牛的平均体重分别为638 kg,546 kg,A组高于B组92.00 kg(P0.01),表明犊牛早期断奶、在满足营养需要的前提下,后期的生长速度比6月龄断奶高。[结论]犊牛早期断奶技术是一项实用技术,值得在养殖场和规模养殖户中大力推广的应用。     

窝产活仔数和初生重与仔猪早期断奶重及成活率的相关性研究

为研究猪窝产活仔数与初生仔猪个体重对21日龄早期断奶仔猪个体重及成活率的相关性,特选择一大型规模猪场2～6胎母猪在1个月内所产的118窝计1350头仔猪作为试验对象,要求所有初生仔猪均由亲本母猪带仔哺乳,且按窝产活仔数不同（6～17头）分组测定仔猪初生个体重和21日龄早期断奶仔猪窝个体均重,并观察断奶成活率,同时对其相关性状作方差及回归分析。结果表明,不同组间初生仔猪窝个体均重和21日龄早期断奶仔猪窝个体均重及断奶成活率差异显著（P〈0．05）;窝产活仔数对初生仔猪窝个体均重和21日龄早期断奶仔猪窝个体均重及断奶成活率呈极显著的负相关（R=-0．802、-0．851、-0．698,P〈0．01）;初生仔猪窝个体均重对21日龄早期断奶仔猪窝个体均重及断奶成活率呈极显著的正相关（R=0．837、0．741,P〈0．01）。试验结果表明,窝产活仔数越多,初生仔猪个体就越小,早期断奶也越轻,成活率也低;初生仔猪个体越大,早期断奶就越重,成活率也越高。只要通过科学合理的方法,适当控制猪窝产活仔数并提高初生仔猪个体重,能有效提高早期断奶仔猪的生长速度,并可获得更好的经济效益。