Effect of a peat-based feed additive and sow parity on the performance of suckling piglets: a case study

ABSTRACT

This study was conducted to evaluate the benefit of a peat-based additive in reducing the neonatal diarrhoea of piglets, according to sow’s parity. From five consecutive batches, a total of 100 Large White x Landrace sows [50 primiparous (PR) and 50 multiparous (ML)] were randomly allocated to the control (CTR) or treated (TRT) group. The peat additive was provided to TRT piglets from the day of birth to day 7 of life (6 g/day/head). Overall, PR group resulted in lower piglets performance with higher enteric disease incidence compared with ML group. Compared with ML, PR sows had lower BCS at weaning (P < .001), fewer total piglets born, lower average piglet weaning weight (P < .01) and higher incidence of deaths due to enteric disease (P < .05). Regardless parity, TRT group showed a fewer number of litters affected by enteric disease (P < .05). No significant interaction between sow parity and treatment was observed.

KEYWORDS:

• Feed additive
• Peat
• Suckling piglet
• Enteric disease

Highlights

• Peat-based feed additive led to reduce the number of litters affected by enteric disease during the pre-weaning phase in a commercial pig farm.

• Primiparous sows had reduced piglets’ performance and higher incidence of enteric disease compared to multiparous sows.

Introduction

In swine production, the suckling period is a crucial phase affecting the future performance of the animals. At birth, piglets are immunodeficient and dependent upon maternal colostrum for passive immune transfer (Stokes et al. 2004). After 24 hours of age, there is a loss of absorptive ability of immunoglobulin (Ig), making the piglet particularly susceptible to infection during the first days of life (Rooke and Bland 2002; Stokes et al. 2004). The gut microbiota varies across piglets and is less stable than adult animal because parturition switches piglets from a sterile state in the uterus to a densely colonized external environment (Bian et al. 2016).

Neonatal diarrhoea is an ongoing problem in swine production that has a multifactorial aetiology and is correlated with animals' health and performance alterations (Nowland et al. 2019). The main causes include infectious factors, such as viruses (rotavirus, coronavirus), bacteria (Escherichia coli, Clostridium perfringens type A and C, Clostridium difficile) and coccidia (Isospora suis, Cryptosporidium spp.), and non-infectious factors, such as stress, herd management, nutrition strategies and environmental conditions (Calderaro et al. 2001; Wieler et al. 2001; Lippke et al. 2011; Vidal et al. 2019). Moreover, the development of genetic lines with hyperprolific sows has been associated with an increase in the number of piglets that are born underweight and thus are at greater risk for enteric problems in the first days of life (Peltoniemi et al. 2020).

Occurrence of enteric problems in very early life may affect the future performance of pigs and mortality rate during post-weaning and growing phases (Alvarez et al. 2015; Aghakeshmiri et al. 2017), and thus has economic implications. During the suckling period, a very crucial phase, piglets are fully fed on sows’ milk but, depending on the farm strategy, milk replacer and then creep feed may be used to supplement the sow low milk production, stimulate piglets gut mucosa development, enhance growth performance and/or stimulate the feeding behaviour to accustom them to the post-weaning diet (Okai et al. 1976; Fraser et al. 1994; Bruininx et al. 2002b).

Sow parity may also affect the piglet performance. The highest reproductive performance is reportedly observed from third parity sows (Hoving et al. 2011; Knecht et al. 2015), having a lower risk of piglet mortality (Guo et al. 2001). This could be influenced by colostrum and milk production, affecting also the passive immunity transfer (Friendship and O’Sullivan 2014). It is well known that piglets are born anaemic, with relative physiological deficiencies and an immunologically immature status (Lay et al. 2002); this likely contributes to pre-weaning mortality and enteric disease incidence. These findings could be emphasized by the influence of sow parity: primiparous progeny could be subjected to higher mortality and enteric disease challenges.

Due to the European banning of growth promoters in 2006, the use of feed additives has grown to enhance animal performance and health status, mainly by preventing gastrointestinal disorders (Pluske et al. 2007). This is in line also whit the communitarian aim of antimicrobial use reduction (More 2020).

The different types of feed additives currently available include prebiotics, probiotics, acids, minerals, nucleotides, phytoproducts and organic acids. However, the main criticism during pre-weaning phase is the effective feed intake related with the young age but also with the farm feeding strategy.

Among feed additives, peat is a completely natural material composed of water (from 50% to 70%), organic matter (including humus and plant debris) and minerals; since it is a natural material, the composition may vary by the origin and peat-forming plants (Xuehui and Jinming 2009). Peat can be considered as a source of biologically active substances, and is often used as a preventive and therapeutic agent against gastric and digestive problems both in human and animal medicine (Kühnert et al. 1989; Kuhnert et al. 1991; Banaszkiewicz and Drobnik 1994). According to its origin, it can be rich in humic substances (e.g. humic, fulvic, and ulmic acids, and humins) that could alter gut pH, nutrient uptake, feed efficiency, haematological profiles and animal performance (Trckova et al. 2005; Visscher et al. 2019).

The aim of this study was to assess the effect of feeding peat-based feed additive during the first seven days of life on performance and health status until weaning of piglets born from multiparous or primiparous.

Materials and methods

Animals and management

The study was performed in a commercial sow farm that is defined as site 1 of a multi-site production system located in the Mantova province (Lombardy, Italy). Pigs were raised in accordance with the protected designation of origin (PDO) Parma ham production regulation and with EC 120/2008 of the European Council (Council of the European Union, 2008) for pig welfare. This study was carried out on five consecutive batches from selected sows. Hundred sows (Large White x Landrace, ANAS line) and their litters (Duroc line as terminal sire) were monitored from farrowing to 28 days of life (weaning time). A total of 50 primiparous (PR) and 50 multiparous (ML) sows were included in the study. From each parity group, 25 were allocated to the peat treatment (TRT) and 25 were allocated to the control (CTR). From each batch, 20 sows were selected according to parity (10 primiparous, PR; and 10 multiparous, ML), body condition score (BCS), and reproductive performance (for multiparous sows), and randomly allocated to the control (CTR) or treated (TRT) group. Animals were housed in mechanically ventilated farrowing rooms in a single barn from seven days before farrowing. Twenty-four hours after farrowing, cross-fostering was performed between litters according to the sow parity and group, to standardize piglet numbers in order to have an average of 11 piglets for each sow. Overall, the animals were managed according to the general farm herd routine. The five batches of sows had 12.47 ± 0.50 newborn alive piglets per litter, 10.45 ± 0.20 weaned piglets per litter, and a loss during the suckling period equal to 11.30% ± 1.80%.

Diets

All sows were fed according their physiological phase according NRC recommendations (NRC, 2012). Liquid feed (solid:liquid ratio of 1:4) was provided once daily during gestation, and thrice daily after farrowing. Tables 1 and 2 show the composition of the feeds provided to the sows during gestation and lactation and the related feed curves, respectively. As feed was bought from an authorized commercial feed mill, the percentage of each ingredient is unknown.

Table 1. Sow feed composition and feed curves during gestation.

Ingredients	Maize, wheat bran, barley, wheat flour, GMO soybean meal, sunflower meal, beet pulp, calcium carbonate, dicalcium phosphate, sodium chloride, GMO soybean vegetable oil
Chemical composition, % (as fed):
Moisture	12.20
Crude protein	16.00
Fat	4.20
Crude fibre	6.80
Ash	5.70
Lysine	0.68
Methionine	0.25
Calcium	0.90
Phosphorous	0.87
Sodium	0.39
Digestible energy (DE) Kcal/kg (as fed)	3100
Weeks of gestation	kg/sow/day
6–8	2.50
8–10	2.60
10–16	2.80

GMO: genetically modified organism.

Table 2. Sow feed composition and feed curves during lactation.

Ingredients	Soft wheat, barley, wheat flour, wheat bran, rapeseed extraction flour, feed based on dehusked GMO soybean meal, lard, calcium carbonate, soybean oil
Chemical composition, % (as fed):
Moisture	10.62
Crude protein	16.50
Fat	5.00
Crude fibre	5.20
Ash	5.80
Lysine	1.00
Methionine	0.40
Calcium	0.90
Phosphorous	0.60
Sodium	0.20
Digestible Energy (DE) Kcal/kg (as fed)	3250
Days lactating	kg/sow/day
0	0.00
3	3.40
8	4.70
12	5.20
18	6.25
24	7.40

GMO: genetically modified organism.

Starting from day 8 of age, suckling piglets were provided supplementary creep diets, first in a liquid form (from day 8 to13) and then in dry-meal form (from day 14 to28). The compositions of the three creep feeds are given in Table 3.

Table 3. Suckling piglet’s creep feed composition.

Creep feed 1
Ingredients	Soft wheat, dairy products. Hulled barley flakes, soy protein concentrate, wheat gluten, sucrose, lactose, lactose, dextrose, pork plasma, soybean oil, fish fairy LT, L-lysine, calcium carbonate, monocalcium phosphate, sodium chloride, citric acid, L-threonine, DL-methionine, L-tryptophan
Chemical composition, % (as fed):
Crude protein	20.30
Fat	4.50
Crude fibre	1.20
Ash	3.80
Calcium	0.60
Phosphorous	0.50
Sodium	0.40
Lysine	1.40
Methionine	0.40
Creep feed 2
Ingredients	Hulled barley flakes, barley, corn, soft wheat flakes, common wheat, extruded soybean, food industry preparations, dairy products, soy protein concentrate, soybean meal extraction, fish meal, sucrose, pork intestinal mucosa protein hydrolysate, soybean oil, beet pulp, L-lysine, monocalcium phosphate, calcium carbonate, L-threonine, DI-methionine, L-tryptophan
Chemical composition, % (as fed):
Crude protein	18.00
Fat	5.70
Crude fibre	2.90
Ash	4.10
Calcium	0.60
Phosphorous	0.50
Sodium	0.20
Lysine	1.30
Methionine	0.40
Creep feed 3
Ingredients	Barley, dehulled barley flakes, common wheat, corn, soybean meal, wheat flakes, dairy products, extruded soybean, soybean oil, soy protein concentrate, pork intestinal mucosa protein hydrolysate, fish meal LT, L-lysine, calcium formate, rendered animal fat, L-threonine, calcium carbonate, monocalcium phosphate, DI-methionine, L-tryptophan
Chemical composition, % (as fed):
Crude protein	17.50
Fat	5.40
Crude fibre	3.50
Ash	3.60
Calcium	0.50
Phosphorous	0.50
Sodium	0.20
Lysine	1.30
Methionine	0.40

Additives

The peat additive was provided to piglets of the TRT groups from the day of birth to day 7 of life. During the first two days of treatment, peat was smeared on the sow mammary gland; thereafter, it was provided in a plastic creep feeder once daily at 6 g/day/head. Table 4 shows the analytical and chemical parameters of the utilized peat.

Table 4. Analytical and chemical analysis of peat as fed.

Parameters
Water	g/kg	925.00
Crude protein	g/kg	9.00
Fat	g/kg	0.00
Crude fibre	g/kg	22.00
Ash	g/kg	6.00
Sodium	g/kg	0.00
Lysine	g/kg	0.00
Methionine	g/kg	0.00
Pb	mg/kg	<1.00
Cd	mg/kg	<0.10
As	mg/kg	<1.00
Fe	mg/kg	295.61
Humic acids	% p/p	12.15

Measurements

For each sow, visual body condition score (BCS; 1 = lowest, 5 = greatest; Coffey et al. 1999) was recorded the day before the scheduled farrowing date and the day of weaning, by qualified personnel. Data on the productive performance were collected, including the number of live-born, stillborn and mummified per litter. The weight of each litter was measured at farrowing after litter size standardization, and again on the weaning day. The feed consumption (from day 7 to the day of weaning) was measured for each litter. During the trial, all the enteric events and deaths were assessed and recorded by trained personnel.

Statistical analysis

The data were analysed for the normal distribution and homogeneity of the variance before statistical analysis. Data were then analysed according to a completely randomized experimental block design. The difference between averages was assessed using the linear mixed effect (LME) model function of NLME package (Pinheiro et al. 2017) of R v3.6.1 (Team R Development Core 2018). Treatment, parity and interaction between treatment and parity (TRT × Parity) were considered as fixed factors, while batch was taken as a random factor. The value of significance was established at P < .05, with P < .01 and P < .001 indicated where appropriate.

Results

Results for treatment differences are shown in Table 5. The trial sow subsamples (20 per batch) had 11.45 ± 0.20 born alive piglets, and 10.68 ± 0.08 weaned piglets and a pre-weaning piglet mortality rate of 7.00 ± 0.25%. The total number of piglets born differed by parity (P < .001), with higher performance observed in the ML group compared with the PR group. The weight of piglets at weaning was higher in the ML group (P < .001) than PR group. Compared with PR group, ML sows had a greater BCS at weaning (P < .001).

Table 5. Statistical analysis of animal performances according to sow parity, to group of treatment and interaction between parity and group of treatment.

		Parity			Treatment			Parity × Treatment					P
Parameters	Unit	PR	ML	SE	TRT	CTR	SE	PR-TRT	PR-CTR	ML-TRT	ML-CTR	SE	TRT		Parity		TRT × Parity
Litters, farrowing	n	10.00	10.00	0.00	10.00	10.00	0.00	10.00	10.00	10.00	10.00	0.00	1.00		1.00		1.00
Litters, weaning	n	9.60	10.00	0.20	9.80	9.80	0.20	9.60	9.60	10.00	10.00	0.28	1.00		0.00	***	1.00
Sow BCS, farrowing		3.06	3.09	0.07	3.09	3.06	0.03	3.09	3.03	3.09	3.09	0.08	0.38		0.38		0.38
Sow BCS, weaning		2.71	2.88	0.09	2.84	2.76	0.07	2.77	2.66	2.91	2.86	0.10	0.09		0.00	***	0.45
Total piglets born	n	112.30	116.70	2.69	114.50	114.50	1.11	112.40	112.20	116.60	116.80	1.03	1.00		0.02	**	0.91
Total birth weight	kg	167.65	175.66	9.15	170.01	173.30	7.16	166.75	168.55	173.27	178.04	9.06	0.51		0.11		0.76
Average birth weight	n/pig	1.49	1.51	0.05	1.48	1.51	0.06	1.48	1.50	1.49	1.52	0.09	0.45		0.70		0.83
Total piglets weaned	n	102.90	106.50	0.05	104.60	104.80	0.06	103.80	102.00	105.40	107.60	0.09	0.94		0.19		0.46
Total weaning weight	kg	743.69	842.48	55.21	803.61	782.56	24.50	754.66	732.72	852.56	832.41	50.22	0.41		0.00	***	0.97
Average weaned weight	kg	7.22	7.92	0.28	7.69	7.45	0.28	7.27	7.17	8.11	7.74	0.54	0.15		0.00	***	0.40
Deaths	n	9.40	10.20	2.66	9.90	9.70	1.14	8.60	10.20	11.20	9.20	4.70	0.93		0.73		0.43
Death incidence	%	8.32	8.70	2.61	8.55	8.46	0.90	7.54	9.10	9.57	7.83	4.29	0.96		0.85		0.42
Enteric deaths	n	2.60	1.30	0.95	1.70	2.20	0.86	2.00	3.20	1.40	1.20	2.01	0.46		0.06		0.30
Enteric death incidence on total	%	2.30	1.11	0.73	1.46	1.95	0.87	1.73	2.88	1.19	1.02	1.76	0.41		0.04	*	0.26
Enteric death incidence on deaths	%	31.08	15.02	11.09	17.44	28.66	10.30	21.83	40.33	13.05	16.99	17.04	0.17		0.05	*	0.38
Litters affected by diarrhoea	n	4.20	2.40	0.81	1.20	2.10	0.51	1.40	2.80	1.00	1.40	1.22	0.04	*	0.04	*	0.25
Total creep-feed consumption	kg	37.08	40.20	0.06	38.25	39.03	0.03	35.86	38.30	40.64	39.75	0.05	0.77		0.23		0.53
Creep-feed consumption	kg/pig	0.36	0.38	0.54	0.37	0.37	0.32	0.35	0.38	0.39	0.37	0.50	0.79		0.60		0.47
Creep-feed consumption	kg/litter	3.46	3.79	0.29	3.59	3.66	0.24	3.31	3.60	3.86	3.72	0.54	0.78		0.22		0.41
Weight gain	kg/pig	5.73	6.42	0.23	6.20	5.94	0.23	5.79	5.67	6.62	6.21	0.32	0.11		0.00	***	0.37

PR = primiparous; ML = multiparous; TRT = treatment; CTR = control; PR-TRT = primiparous of treatment group; PR-CTR = primiparous of control group; ML-TRT = multiparous of treatment group; ML-CTR = multiparous of control group; SE = standard error. Significance ***P < .001, **P < .01, *P < .05.

The number of litters affected by enteric events was positively influenced by the treatment (P < .05), where TRT groups had a lower number of litters affected by enteric disorders compared to CTR group. Despite the lack of the interaction TRT × Parity effect, ML-TRT sows had lower average number of litters affected by enteric diseases than the PR-TRT group.

The enteric mortality was expressed as the percentage that died from enteric disease as a function of the overall percentage of piglets that died per litter. The enteric mortality was affected only by parity (P = .04). The ML sows registered the lower value.

Piglets’ feed consumption, from seven days of life to weaning, was comparable between PR and ML sows and between the TRT and CTR groups. However, piglets’ weight gain was significantly higher in the ML group (P < .001).

Discussion

The results obtained in this trial were not fully comparable with results found in the literature. Here, we tested the use of a peat-based additive for its ability to reduce the enteric mortality during the first days of life and, hence, improve the performance and survival of piglets. In fact, the studies available to date are mainly focused on fattening phase and only one study on pre-weaning stage, although providing peat from days 5 to 21 (Trckova et al. 2006). The same authors did not report any effect on body weight gain. Peat was also considered an economically ineffective additive in fattening pig stage due to the lack of effect on the growth performance, metabolic profile or health status (Trckova et al. 2005, 2006; Matlova et al. 2012).

In this study, the treatment did appear to reduce the number of litters affected by enteric disease. This might reflect the positive effects of humic and fulvic compounds, as these organic acids are naturally present in humus, which in turn have antioxidant and chelating activities that could indirectly improve the utilization of minerals by pigs (Ferronato and Prandini 2020). Visscher et al. (2019) supplemented piglets with humic acid-rich peat and found no alteration of performance parameters but did observe changes in the fermentation level of cecal and colon contents with a reduction of short-fatty acids in the cecal content and differences for bacterial relative abundance. Instead the direct supplementation of humic substances (i.e. humic acids, fulvic acids, humate) showed greater benefits on the reduction of enteric problems (Golbs et al. 1986; Fuchs et al. 1990; Trckova et al. 2017; Tunc and Yoruk 2017).

We did not find a significant effect of the interaction between peat treatment and sow parity but there was a significant effect of the latter on reproductive performance, which is in line with previous works. A previous study showed that the parity of sows impacts the performance of their offspring (Moore 2001). Here, we observed that PR sows had decreased performance in terms of BCS loss, the number of piglets weaned, total number of stillborn piglets and the weight of piglets at weaning. The lower PR performance could be due to several factors including the rearing of gilts, age at first mating and farrowing, environmental factors and feeding management, which are associated with the greater needs of energy and growth in primiparous sows.

The lower piglet weaning weight found herein for the PR group could be explained by poorer milk and colostrum production and quality, which would correlate with a reduced passive immune (IgG) transfer to piglets. In contrast to the reports of Craig et al. (2017, 2019), the live-born weight did not differ between the PR and ML groups. This would result in the average weight gain of piglets being higher for ML sows than PR sows. Indeed, Moore (2001), Milligan et al. (2002) and Miller et al. (2012) found reduced performance in piglets of PR sows, and suggested the need to addressed this by providing supplemental milk during the suckling period. The pre-weaning mortality was similar between the PR and ML groups and slightly lower than Koketsu (2000), while the average enteric rate and the number of litters affected by enteric disease in the PR group were double of the ML group. Craig et al. (2019) reported that reduced performance of primiparous progeny could be due to reduced production of colostrum and milk instead of reduced concentrations of IgG, protein or fat. Conversely, Pinheiro et al. (2017) suggested that IgG content could be reduced in primiparous sow-derived piglets due to their incomplete acquisition of specific immunity. The remaining mortalities could be explained by piglets being crushed as the sow changes position (Lay et al. 2002). Among non-infectious factors listed as causes of pre-weaning mortality, there are piglets’ factors (i.e. birth weight, vitality, gender), environmental factors (i.e. season and temperature, housing, management) as well as sow factors. Among the latter, there are the colostrum composition, maternal stress during farrowing time, parity and sow nutrition. The negative correlation between pre-weaning mortality and primiparous sows may be explained by the lower piglets weight, the lower colostrum yield and farrowing experience (Muns et al. 2016). Ferrari et al. (2014) reported that piglets suckled by multiparous sows have better growth performance than primiparous piglets even if sow parity of the biological dam did not affect piglets’ survival and growth.

The average creep-feed intake (0.360 kg/piglet) was in the range previously proposed by several authors (Bruininx et al. 2002a, 2004; Sulabo et al. 2010). Even if creep-feed consumption was not different between the groups, the increased weight gain and weight at weaning time seen in the ML group could be explained by improvements in the mucosal adsorptive capacity and nutrient uptake. We could speculate that the improved feed efficiency among piglets could have interacted with the sow BCS, reducing the loss of BCS by decreasing milk demand and ameliorating the negative energy balance (Buckley et al. 2003; Yan et al. 2011; Pustal et al. 2015).

Instead of (or in addition to) providing benefits as a feed additive, the peat could have acted as a stimulus to explore the environment, promote solid feed ingestion and reduce aggression during the post-weaning phase (Kuller et al. 2010; Vanheukelom et al. 2011; Middelkoop et al. 2019). This is relevant because we did not monitor the piglets’ behaviour in the present study, and thus cannot be assured that the peat was fully ingested.

Conclusions

This study showed that peat could also be administered in the suckling phase to support gut health and reduce enteric disease in suckling piglets, starting from birth.

However, considering the lower performance of litters primiparous sows, there was no significant interaction between treatment and sow parity. Further studies should be developed considering a longer period of peat-based feed administration and evaluating the effects in the later post-weaning period.

Ethical approval

This study complied with Italian laws on animal experimentation (DL n. 26, 04/03/2014).

Disclosure statement

No potential conflict of interest was reported by the author(s).