Preweaning piglet mortality in Mauritius

VS Jugessur

Agricultural Research and Extension Unit

ABSTRACT

About 10 to 15% deaths usually occur in piglets from their birth until they are weaned at the age of about 8 weeks from their mothers. Mortality rates exceeding 15% constitute serious overhead expenses in any piggery across the world. The causes of preweaning piglet mortality are varied and may be due to predisposing factors such as bad management, susceptibility to diseases, sow health and extremes of weather. A study carried out from June 1996 to February 1998 on 18 piggeries and in different regions of the country and involving 100 randomly selected sows and their three consecutive litters of piglets has enabled the identification of the factors associated with the causes of piglet mortality and mortality rates due to these. Mortality rates of 17.2%, 19.3% and 24.6% recorded in each cycle were mainly due to overlay, starving, undersized piglets and enteritis.

Keywords: Pigs, weaning; mortality, causes, mortality rates, Mauritius.

INTRODUCTION

Piglets are usually weaned from their mothers at around 45-56 days of age, at which time they can feed themselves on feeds of both animal and plant origin, and have developed the capacity to resist infection from the environment. However, out of the litters of piglets that are born, some 10 to 15% do not survive till weaning time and this mortality rate can be much higher due to various factors. Predisposing factors like overcrowding, bad ventilation, malnutrition, susceptibility to viral and bacterial infection and extremes of weather, and some common factors like enteritis caused by colibacilli, sow health and litter size are major contributing factors of preweaning piglet mortality. Inadequate spatial arrangements and nursing care of piglets cause more than half of the preweaning deaths during the first 36 hours of life and during the following 3 to 4 days (Leman et al 1992).

In Mauritius, preweaning piglet mortality has been a serious problem faced by pig farmers in the smallholder sector, as revealed by a Rapid Rural Appraisal and a Participatory Rural Appraisal that were carried out in 1995 and 1996 respectively, by the Agricultural Research and Extension Unit. These also revealed that besides inflicting heavy economic losses through piglet mortality rates of up to 50% on many farms, the increasing demand for weaners both for breeding and fattening could not be met. A study on preweaning piglet mortality was therefore carried out on selected piggeries in 3 different regions of the island over a period of one and a half years from June 1996 to February 1998 to elucidate the causes associated with such mortalities and to propose remedial actions so as to reduce piglet mortality.

MATERIALS AND METHODS

Eighteen pig farms of varying size and having different management practices were identified from three regions of the country namely, super humid (annual rainfall over 2500mm rain), humid (1500-2500 mm rain) and sub humid region (less than 1500mm rain) as shown in Table 1. These farms comprised 3 individual piggeries, 13 cooperative farm units, one prison farm, one government livestock production unit, and one farm run by the Federation of Young Farmers. A random sample of 100 (Large White, Landrace and crosses of these) gestating sows and gilts, mostly of parity 1 and 2 were taken from a total of 313 present on the 18 farms.

Table 1 Selection of farms

Farms	Region
	Super humid	Humid	Sub humid	Total
Small ( Up to 50 heads )	1	2	0	3
Medium ( 50 - 100 heads )	1	4	3	8
Large ( Over 100 heads )	1	3	3	7
Total	3	9	6	18

The farms were visited regularly; case histories of individual sows, boars and litters as well as management practices for the three consecutive reproduction cycles (Litters I, II and III) were recorded on each farm.

EXPERIMENTAL INVESTIGATION

On-farm observations

Management practices related to housing, feeding, reproduction, sanitation and health care were recorded separately for each farm.

Weighing of piglets

Piglets were weighed between day old and 4 days in Litter I only. Birth weights of 180, 481 and 90 piglets from sows of parity 1, 2 and 3 respectively were recorded.

Detection of parasitic infestation

Quantitative analysis of 193 fresh faecal samples from gestating sows and 104 samples from 3 to 4 week old piglets respectively was carried out for endoparasitic helminths and coccidia, by concentration and sedimentation technique using saturated salt solution.

Recording of diseases

Diagnosis of diseases were made on the spot, from case histories of individual sows and of litters as well as from post mortem findings and by the isolation of pathogenic bacteria.

Determination of litter size, preweaning piglet mortality and number of piglets weaned

Mean values were calculated for individual as well as for aggregate farms for 100 first litters, then for second 66 litters and ultimately for 50 third litters from actual observations as well as on information obtained from the farmers.

Identification of the causes of deaths

The factors associated with, as well as the causes of deaths of sows and of piglets from birth until weaning were identified in each cycle, from history, post mortem examination and as stated by farmers.

RESULTS

Litter size, preweaning piglet mortality, stillbirths and weaning rate (Table 2). 100 sows and gilts and their litters were studied in the first cycle (Litter I) while in the second cycle following deaths of some sows and farmers culling unproductive ones, the number of sows and their litters (Litter II) were reduced to 66 and finally 50 sows and their litters (Litter III) were left for the third cycle.

Table 2 Litter size, preweaning piglet mortality, stillbirths and piglets weaned in three consecutive reproduction cycles.

	Litter I	Litter II	Litter III
No. of farms	18	13	11
No. of sows & litters	100	66	50
No. of piglets born alive	945	630	512
No. of piglets dead*	163	122	126
Preweaning mortality %*	17.2	19.3	24.6
Stillbirths	41	15	12
No. of piglets alive / litter	9.4 ± 1.4**	9.5 ± 2.2**	10.2 ± 1.4**
No. of piglets weaned / litter	7.8 ± 1.4**	7.7 ± 2.0**	7.7 ± 2.1**

* Does not include stillbirths ** S.E ± - Standard Error

Litter size

The mean litter size for Litter 1 was 9.4 ± 1.4; for Litter II was 9.5 ± 2.2 and for Litter III it was 10.2 ± 1.4, excluding stillbirths.

Preweaning piglet mortality

The mortality rates in Litter 1 ranged from 0-34.2% with a mean of 17.2 %, in Litter II from 0-46.6% with a mean of 19.3 % and in Litter III from 0-80% with a mean of 24.6%. The mean mortality rates for the ultimate 50 sows that gave 3 consecutive litters were 17.6%, 29.1% and 24.6% for Litter I, II and III respectively.

Stillbirths

The incidence of stillbirths was low (4.1%, 2.3% and 2.2 % for Litters I, II and III respectively). The stillbirths were not taken into account while computing the results.

Piglets weaned per litter

A mean of 7.8 ± 1.4 (n=782) piglets was recorded for Litter I, 7.7 ± 2.0 (n=508) for Litter II and 7.7 ± 2.1 (n=386) for Litter III.

Birthweight of piglets

The mean birth weight of piglets at 0 to 4 days of age in Litter I from sows of parity 1, 2 and 3 were 1.23 ± 0.27 kg (n=180); 1.24 ± 0.19 kg. (n = 481) and 1.29 ± 0.26 kg (n = 90) respectively.

Causes of preweaning piglet mortality

The main causes of deaths in all the 3 litters were found to be overlay, starving, undersized piglets, diarrhoea and these represented 27.9%, 26.2%, 18.9% and 15.5% respectively of all the deaths of the three litters combined. The other causes of lesser importance were septicemia (3.6%), anaemia (1.9%), savaging (0.97%), atresia ani (imperforate anus) (0.72%), pneumonia (0.48%) and splay legs (0.48%) (Table 3).

Table 3 Causes of preweaning mortality for the three cycles combined

Cause	Number of deaths	Number of deaths autopsied	% Deaths due to each cause
Overlay	115	33	27.9
Starving	108	22	26.2
Born Weak	78	36	18.9
Diarrhoea	64	30	15.5
Septicemia	15	15	3.6
Unknown	12	-	2.9
Anaemia	8	8	1.9
Savaged	4	-	0.97
Atresia Ani	3	3	0.72
Splay legs	2	2	0.48
Pneumonia	2	2	0.48
Total	411	151	100

Percentage deaths of total deaths recorded as well as of total piglets born due to all these causes in each of the three reproduction cycles and in the superhumid, humid and subhumid regions are given in Tables 4, 5 and 6.

Table 4 Causes of preweaning mortality in each reproduction cycle Litter I, II & III

Cause of death	Litter I		Litter II		Litter III
	Number of deaths	% Total deaths (n=163)	Number of deaths	% Total deaths (n=122)	Number of deaths	% Total deaths (n=126)
Overlay	41	25.1	40	32.7	34	26.9
Starving	38	23.3	24	19.6	46	36.5
Born Weak	34	20.8	31	25.4	13	10.3
Diarrhoea	26	15.9	17	13.9	21	16.6
Septicemia	15	9.2	-	-	-	-
Anaemia	-	-	8	6.5	-	-
Savaged	2	1.2	-	-	2	1.5
Atresia ani	2	1.2	-	-	1	0.79
Pneumonia	1	0.61	-	-	1	0.79
Splay legs	-	-	2	1.6	-	-
Unknown	4	2.4	-	-	8	6.3
Total	163	100	122	100	126	100

Parasitic infestations

Presence of helminth parasites and coccidia was detected on 16 farms (88%) in pregnant sows and on five farms (28%) in piglets 3 to 4 weeks of age. Helminth ova of Ascaris suum, Oesophagostomum dentatum, Trichuris suis, Strongyloides ransomi, Megastrongylus apri, Stephanurus dentatus and Coccidia oocysts of Eimeria species were identified.

Table 5 Preweaning mortality of piglets born in each reproduction cycle due to different causes

Causes	Litter I		Litter II		Litter III
	Number of deaths	% of total born (n=945)	Number of deaths	% of total born (n=630)	Number of deaths	% of total born (n=512)
Overlay	41	4.3	40	6.3	34	6.6
Starving	38	4	24	3.8	46	7.3
Born Weak	34	3.6	31	4.9	13	2.5
Diarrhoea	26	2.7	17	2.7	21	4.1
Septicemia	15	1.6	-		-
Anaemia	-		8	1.2	-
Savaged	2	0.2	-		2	0.4
Atresia ani	2	0.2	-		1	0.2
Pneumonia	1	0.1	-		1	0.2
Splay legs	-		2	0.3	-
Unknown	4	0.4	-		8	1.5
Total	163	17.2	122	19.3	126	24.6

Table 6 Preweaning mortality in different climatic regions

Causes	Super humid		Sub humid		Humid
	Deaths
	Number	%	Number	%	Number	%
Overlay	4	66.6	68	30.9	43	23.2
Starving	-	-	70	31.8	38	20.5
Born Weak	1	16.6	24	10.9	53	28.6
Diarrhoea	1	16.6	30	13.6	34	18.3
Septicemia	-	-	7	3.1	8	4.3
Anaemia	-	-	8	3.6	-	-
Savaged	-	-	2	0.9	2	1.0
Atresia ani	-	-	3	1.3	-	-
Pneumonia	-	-	-	-	2	1.0
Splay legs	-	-	2	0.9	-	-
Unknown	-	-	7	3.1	5	2.7
Total	6	100%	220	100%	185	100%

DISCUSSION

Management of farrowing pens

Farrowing crates

Up to 20% of preweaning deaths may be due to overlay in piggeries where farrowing crates are not well designed (Leman et al 1993; Rao et al 1992). Non confinement of sows in farrowing crates or confinement in improperly designed ones resulted in overlay which caused 41 deaths (25.1%) in Litter I, 40 (32.7%) in Litter II and 34 (26.9%) in Litter III (Table 4). It was also observed that out of 18 farms, 6 (33.3%) had farrowing crates and on only 3 farms (16.6%) the farrowing crates were well designed. On one of the latter 3 farms which was also the largest (496 head) and had the best designed farrowing crate, the lowest mortality rates of 7.3%, 7.6% and 7.0% were recorded in the respective litters as compared to the average 17.2%, 19.3% and 24.6% for all the farms in the respective Litters I, II and III. On this farm no death was reported to be caused by overlay thus showing the usefulness of a well-designed farrowing crate.

Sanitation

Well drained floors enabling proper disposal of faeces and urine were found in 9 farms (50%) (two government owned and seven private farms). However, routine disinfection was carried out on only one government farm, where the maternity pen was disinfected before introduction of the sow. Of the 411 total deaths recorded for the three reproduction cycles combined, 15.5% were due to diarrhea and enteritis and this can be associated with poor hygiene which is an enteritis risk factor. It has been reported (Leman et al, 1992) that 5-15% deaths of piglets can be due to viral and bacterial infections, which cause enteritis and death. In the study, E. coli was isolated from 15 (3.6%) deaths due to septicemia.

Creep area and creep feeding

Although creep area was adequate and creep heat was provided on 12 (66.6%) farms, bedding for comfort of piglets was provided on only 6 (33.3%) farms. Creep feed fed to piglets after one week of age enables them to build up immunity since the sow’s milk production as well as its lactose content fall after about 2 weeks after farrowing (Leman et al, 1992). It was observed that creep feed was given on 12 (66.6%) farms, but on 9 of these (75%) the piglets had access to the sows ration as well.

Animal-farmer interaction

On 7 farms (38%), farmers were present at the time of parturition and would provide assistance to the sows and piglets if required. Obviously, mortality rate due to overlay could have been reduced if there were more animal-farmer interaction during the first days following farrowing.

Health Care

Iron injection was given to piglets on 17 (95%) farms, but on only 7 (38.8%) farms it was given at the recommended time, that is at 3 days. Although iron injection was not given at 3 days, yet preweaning piglet mortality due to anaemia was only about 2% for the three cycles combined and was therefore not a serious problem. Animals were dewormed regularly during each cycle on 9 (50%) farms and treatment against diarrhoea was given promptly on 8 (44.4%) farms whereas almost all farmers complained of not receiving timely veterinary assistance which contributed to death of piglets suffering from diarrhoea.

Sow factors affecting piglet mortality

Nutrition of gestation sows

On 5 (28.5%) farms concentrates were fed adequately and the amount fed was increased during the last fortnight of gestation. This is essential so as to allow the foetus to accumulate energy reserves (Leman et al 1992). Only swill and garbage were fed to the sows on 2 farms (11.1%), although these feeds were normally given to fatteners. On the latter farms, all the sows under study were sold because of poor condition, after the first cycle. Apart from two Government farms, on the remaining 16 farms very often the ration of pregnant sows included cooked or uncooked swill and very less concentrates as the farmers found it to be more economical to feed swill. The nutrition of gestating sows is considered to be very important as an inadequate supply of milk to piglets can cause a high rate of preweaning deaths due to starvation. One hundred and eight (26.2%) deaths of piglets was due to starving piglets that were unable to get sufficient milk from both agalactic sows and those affected by perihypogalactic syndrome (PHS) (Table 3). PHS which was observed in 18 (18%) sows could be associated with nutrition and not to infectious causes, since mastitis was detected on only one affected sow. A few farmers resorted to fostering the piglets from agalactic to other sows but this did not reduce mortality. Nutritional deficiencies could also have been responsible for small, non-viable piglets which were the cause of 77 (18.9%) of the total deaths for the 3 cycles combined and for a peak of 25.4% in the second cycle.

Hereditary factors

Sow factors also included although to a lesser extent, hereditary factors which must have been associated with deaths of piglets due to atresia ani and to splay legs (Leman et al, 1992), as well as to mismothering and savaging.

Mortality in different climatic regions

From the range of mortality rates recorded in the study and the causes thereof in the super humid, humid and subhumid regions, it was not evident that mortality rates could be directly related to any particular region (Table 6).

CONCLUSION

Four main factors namely: feeding of gestating sows, arrangements in farrowing pens, sanitation and control of diarrhoea in piglets were closely associated with a relatively high preweaning piglet mortality rate. The main causes of deaths were identified as overlay, non viable piglets, starving, insufficiency of milk for suckling piglets and enteritis. The preweaning death losses in piglets could be considerably reduced if farmers would improve sow nutrition, provide well-designed farrowing crates, disinfect farrowing pens and attend promptly and efficiently to scouring piglets.

ACKNOWLEDGEMENTS

The author gratefully acknowledges the assistance received from the Division of Veterinary Services, Ministry of Agriculture, Food Technology and Natural Resources; Mr V. Vally, Assistant Research Scientist, Livestock Research Department, AREU; the Commissioner of Prisons; the Manager of Federation Young Farmers and all the farmers who allowed access to their farms and supplied information.

REFERENCES

Leman AD, Straw BE, Mengeling WL, D’Allaire S, Taylor DJ. 1992. Diseases of swine, Iowa State University Press/AMES, IOWA, USA.

RAO AN et al. 1992. Mortality pattern in piglets - a statistical analysis. Indian Journal of Animal Science Vol.63 (7).