Oregano improves reproductive performance

of sows

Peter Allan, Gabor Bilkei*

Raubbuhlstrasse 4, CH-8600 Dubendorf, Switzerland

Received 1 April 2003; accepted 30 June 2003

Abstract

Natural herbs are being explored as alternatives to antimicrobials. The objective of the present

study was to determine the effect of strategic addition of oregano to prefarrowing and lactation diets

of sows under field conditions. Alternate farrowing groups were given diets containing 1000 ppm

oregano (dried leaf and flower of Origanum vulgare, enriched with 500 g/kg of cold-pressed essential

oils of O. vulgare) in prefarrowing and lactation diets. Overall, 801 oregano-treated sows, including

601 primiparous and 1200 multiparous (parity 2.99 � 0.43, mean � S.E.) and 1809 untreated control

sows (705 primiparous and 1104 multiparous; parity 3.04 � 0.38), were used. Sows fed oregano had

lower annual sow mortality rate (4.02 � 0.4% versus 6.92 � 1.11%, mean � S.E.; P ¼ 0.003), lower

sow culling rate during lactation (8.01 � 1.11% versus 14.02 � 1.33%, P ¼ 0.02), increased

farrowing rate (77.02 � 2.31% versus 69.91 � 2.32%, P ¼ 0.01), increased number of liveborn

piglets per litter (10.49� 1.5 versus 9.95 � 1.22, P < 0.05), and decreased stillbirth rate (0.909� 0.01

versus 0.807 � 0.01, P ¼ 0.05). In addition, multiparous sows fed oregano had higher (P ¼ 0.04)

daily voluntary feed intake compared to non-treated sows (7.7 � 0.32 kg versus 7.0 � 0.42 kg,

P ¼ 0.04). Additional studies are needed to elucidate the effects of oregano on the gastrointestinal,

immune and urogenital system in swine and to determine if it has any adverse effects.

# 2004 Elsevier Inc. All rights reserved.

Keywords: Sow mortality; Oregano; Farrowing rate; Litter size; Stillbirths

1. Introduction

Non-specific immunostimulators, synthetic peptides, natural herbs and fermentative

microorganisms are currently being studied for their use in animal nutrition [1]. Probiotics,

vitamins, amino acids and minerals are well established in animal nutrition for enhance-

ment of immunity, altering microbial flora and reducing the incidence of disease [1]. Sow

mortality markedly influences the economics of pig breeding units [1]. Although anti-

Theriogenology 63 (2005) 716–721

* Corresponding author. Tel.: þ41 1 820 02 26

0093-691X/$ – see front matter # 2004 Elsevier Inc. All rights reserved.

doi:10.1016/j.theriogenology.2003.06.010

microbial feed additives reduced infectious sow mortality [1,2], European restrictions on

use of antimicrobial feed additives were associated with increased sow mortality because

of urogenital infections [1]. Furthermore, periparturient bacterial diseases significantly

increased sow mortality [3].

Antimicrobial feed additives benefit production by increasing profitability [4,5], redu-

cing the discharge of animal wastes into the environment [6], and diminishing the number

of pathogens [7]. Natural, safe and inexpensive feed additives that do not endanger the

environment with residues in wastes would be of considerable benefit. It is noteworthy that

there is a revival of phytogenic feed additives (especially oregano) in Eastern Europe [8], as

a successful alternative to the prophylactic use of antibiotics against swine dysentery [9].

Oregano feed supplementation positively influenced daily feed intake, daily weight gains,

and feed utilization in growing pigs [10–12] and improved farrowing rate in sows [8].

Khajarern and Khajarern [13] stated that origanum essential oils act not only as alternative

antibacterial performance promoters, digestion aids, and appetite enhancers in sows, but

also as natural feed additives, enhancing growth and reproductive performance in sows.

The objective of the present study was to determine the effects of strategic addition of

oregano to prefarrowing and lactation diets of sows under field conditions. The hypothesis

was that the antibacterial, anti-inflammatory, antioxidant, and appetite-enhancing ability of

essential oils in oregano [8] would enhance voluntary daily feed intake and farrowing rate,

reduce mortality and culling rates, improve liveborn litter size, and decrease stillbirth rate.

2. Materials and methods

2.1. Management

This trial was performed in Alfold, Hungary from 1999–2003. A large indoor herd of

2100 sows of similar genetics, typical for this geographic area (F1 and F2 Large White X

Landrace females mated to Duroc boars) was used. Replacement gilts (140–151 days of

age) were introduced from the nucleus herd at an annual replacement rate of 39.1–48.2%.

The animals were bred when standing estrus was first observed. Sows were artificially

inseminated (AI) at first postweaning estrus; after positive pregnancy diagnosis, they were

moved into gestation barns. On the 109 or 110th day of pregnancy, sows were moved into

farrowing barns for the duration of lactation (3 weeks). Sows were kept in high-investment

indoor facilities (farrowing crates, individual gestation crates, breeding area). Standard

farm management included weaning at 3 weeks of lactation, group rotation system of

27–30 females, double artificial insemination, and mandatory culling after parity 9.

2.2. Herd history

Prior to the start of the study (1989–1998), sow mortality rates in this herd were

6.2–8.1% per annum. Furthermore, this herd had a pre-trial (1998) annual culling rate of

44.3% (14.7% for reproduction, 9.1% locomotion problems, 5.5% torsion of abdominal

organs, 4.9% heart failure, 6.9% culling because of old age, and 3.2% miscellaneous

causes).

P. Allan, G. Bilkei / Theriogenology 63 (2005) 716–721 717

2.3. Nutrition

From AI to day 89 of pregnancy and from days 90–100 of pregnancy, sows were fed 2

and 3 kg per day, respectively, of a commercial gestation ration that contained (on a per kg

basis) 12.2 MJ digestible energy, 125 g crude protein, 6.5 g lysine, 8 g calcium, and 6 g

phosphorus. The lactation diet (13 MJ digestible energy, 180 g crude protein, 10 g lysine,

8 g calcium and 6 g phosphorous) was fed at a rate of 3 kg/day from day 110 of pregnancy

to parturition, 1 kg on the day of parturition, and ad libitum starting on the second day after

parturition. On the day of weaning, no feed was given to the sow. From 2 days after

weaning to breeding, the sows received ad libitum the same lactating diet, supplemented

with 300 IU Vitamin E per kg and 500 g potato starch/sow/day [8].

2.4. Experimental design

Alternate farrowing groups of sows were given lactating diets supplemented with

1000 ppm oregano (Oregpig1 Pecs, Hungary). Supplementation was done from day

109 � 0.4 (mean � S.E.) of pregnancy to the day of AI. The supplement consisted of

dried leaf and flower of Origanum vulgare, enriched with 500 g/kg of cold-pressed

essential oils of O. vulgare. Each kg of supplement contained 60 g carvacrol and 55 g

thymol.

Sows fed oregano and control sows were present at the same time and in the same

facility. All farrowing barns had identical management and nutrition. On day 110 of

pregnancy, body condition scores were performed as described by Bilkei and Biro [14].

Piglets were cross-fostered within 24 h of birth to equalize litter size (9–11 piglets). The

reduction in sow weight and backfat during lactation were not recorded. Litters were

weaned at 22.3 � 2.4 days versus 22.4 � 21.1 (mean � S.E.) days of lactation in the

oregano versus control groups. Estrus detection began 3 days after weaning.

The current study included 1801 oregano-treated sows (601 primiparous, 1200 multi-

parous, parity 2.99 � 0.43, body condition 3.3 � 0.25) and 1809 untreated control sows

(705 primiparous, 1104 multiparous, parity 3.04 � 0.38, body condition 3.4 � 0.17),

managed in farrowing subgroups of 27–30 sows.

2.5. End points and statistical analyses

Possible outcomes for sows after farrowing included death, culled, bred but returned to

estrus, or farrowed. If the sow farrowed another litter, the subsequent litter size was

recorded. Statistical analyses were performed using the General Linear Model Procedure

of SAS1 [15] to derive least-squares means and standard errors. In the model, parity and

treatment were included as classes, and the dependent variables were weaning to estrus

interval (WEI) and subsequent litter size. The month of weaning, body condition at

farrowing, and feed intake during lactation were significant and therefore were included as

covariates. Full lactation length, full litter size suckled, numbers of piglets removed, and

number of piglets remaining with the sow had no significant effects on WEI or subsequent

litter size; therefore, they were not included as covariates. Sow mortality and culling rate

were examined by logistic regression. The stillbirth effect was examined with a multi-

718 P. Allan, G. Bilkei / Theriogenology 63 (2005) 716–721

variate Poisson regression (controlling for parity and genetic line). Farrowing rates were

compared by Chi-square.

3. Results and discussion

Average voluntary daily feed intake was similar for oregano-supplemented and control

primiparous sows (5.6 � 0.71 kg versus 5.5 � 0.80 kg, P > 0.05), but was higher in

oregano-supplemented versus control multiparous sows (7.7 � 0.32 kg versus 7.0 �0.42 kg, P ¼ 0.04). Oregano treatment reduced annual sow mortality rate (4.02 � 0.4%

versus 6.92 � 1.11%, P ¼ 0.003) and reduced the rate of sow culling during lactation (8.01

� 1.11% versus 14.02 � 1.33%, P ¼ 0.02). Furthermore, oregano treatment increased

farrowing rate (77.02 � 2.31% versus 69.91 � 2.32%, P ¼ 0.01), increased the number of

liveborn piglets per litter (10.49 � 1.5 versus 9.95 � 1.22, P < 0.05), and decreased

stillbirth rate (0.909 � 0.01 versus 0.807 � 0.01, P ¼ 0.05). Overall, oregano-treated sows

had an increase in subsequent output of 0.78 piglets per sow treated (for that parity and

subsequent farrowing), attributed to increases of 0.1, 0.18, 0.2, 0.2 and 0.1 piglets per sow

because of the reduced stillbirth rate, improved liveborn rates, reduced sow mortality,

reduced sow culling, and improved farrowing rates, respectively.

The principal reasons for culling and mortality of oregano-fed versus control sows were:

anestrus (16% versus 15%); locomotor problems (21% versus 21%); swine urogenital

disease (SUGD; 13% versus 22%), periparturient diseases (i.e., mastitis-metritis-agalactia,

MMA; 15% versus 25%), heart failure (21% versus10%) and miscellaneous reasons (8%

versus10%). The majority of culling because of anestrus occurred in September and during

the winter months, indicating that adverse environmental conditions (summer heat and

cold-wet winter) suppressed reproductive activity. Both SUGD and MMA are prevalent in

intensive management systems [16]; in a large Eastern European breeding company,

SUGD caused 32.4% of sow deaths and MMA occurred in 40% of births [17,18]. In the

present study, oregano application diminished SUGD as a cause of sow death by 59.1% and

MMA by 60%.

Phytogenic feed additives as growth promoters are controversially discussed in the

literature [7,13,14,19–22]. The positive effect of dietary oregano on sow health and

production may be because of the effects of oregano etheric oils; these oils exert

antioxidant [23], antibacterial [24], antiphlogistic [25], and anti-inflammatory [25] effects.

Khajarern and Khajarern [13] stated that carvacrol and thymol affected the mucosal

membrane in the intestines and accelerated the renewal rate of enterocytes on the surface

intestinal villi; this would reduce pathogen attachment to enterocytes and improve nutrient

absorption capacity. Furthermore, these authors stated that origanum essential oils act not

only as alternative antibacterial performance promoters, digestion aids, and appetite

enhancers in sows, but also as natural feed additives to enhance growth and reproductive

performance in sows [13]. Oregano stimulated organic and microbiotical digestion [19],

enhanced the regulation of gastrointestinal metabolism [10] and exerted antibacterial

properties by hindering dysbiotic processes in the digestive tract of pigs [20–22,24]. In one

study, feed supplementation with 1000 ppm oregano during the postweaning period

significantly improved weight gain and health of pigs [12]. Dietary supplementation with

P. Allan, G. Bilkei / Theriogenology 63 (2005) 716–721 719

origanum essential oils significantly increased daily feed intake and milk production of the

lactating sow [13]. Similarly, in the present study, lacational feed intake was significantly

higher in oregano-fed multiparous sows.

The effects of oregano on sow fertility can only be speculated. If oregano stabilizes gut

microflora, decreases populations of undesirable microorganisms, and increases the

digestibility of the feed, general health may be improved and postparturient immune

system activation may be positively influenced by diminishing the deleterious effects of

delayed immune response and reduced leukocyte activity of the postpartum sow uterus [8].

Consequently, uterine involution may be hastened and the sow better protected from

postpartum urogenital infections. In that regard, rapid uterine involution increased sub-

sequent farrowing rates [8] and anti-inflammatory and antioxidant treatment reduced the

occurrence of MMA and SUGD [8].

In one study [26] lactating sows were fed 1000 ppm garlic, 1000 ppm horseradish,

50 ppm enrofloxacin, or no supplement. It was noteworthy that sows given horseradish and

enrofloxacin had a significantly lower incidence of MMA and SUGD (compared to those

given garlic or no supplement). Horseradish contains natural phenols (similar to oregano)

that may provide protection against periparturient disorders of the sow and therefore may

be a viable alternative to antibiotics. Therefore, there may be other natural phenols that

protect sows against periparturient disorders.

In conclusion, oregano enhanced sow health and productivity and may be a viable

alternative to supplementation with antibiotics. However, that a feed additive is of natural

origin does not necessarily make it safer or better than other additives. In that regard, many

antibiotics are of natural origin (i.e. originating from molds). Although there were no

apparent deleterious effects of oregano in the present study, further study is needed to

determine if there are harmful effects, particularly with supplementation at higher

concentrations. Furthermore, basic research is needed to clarify the effects of oregano

on the gastrointestinal, immune and urogenital systems.

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