Alternative Animal Feeding for Intensive Livestock Farming Systems and Their Impact on Reproductive Performance of Ruminants

Abstract

Intensive livestock farming systems are vital for sustaining the growing world population by providing several goods and services. However, the increased livestock operations cost, particularly related to animal feeding, compromises the expansion of this industry, especially in developing countries. One way to reduce the feeding costs without compromising the nutritional quality would be the use of protein-rich food waste discarded by the industries that otherwise would pollute the environment. This chapter presents an overview of the intensive livestock farming systems in developed and developing countries and discusses the use of agro-industrial by-products as alternative sources of nutrients to improve livestock productivity, as well as the key nutritional components that are likely involved to improve the reproductive performance of animals. Our results showed that diets containing 30 to 45% of coconut meal, rich in ether extract and protein, may improve sperm progressive motility, sperm concentration per mL, total sperm per ejaculate, and total viable sperm per ejaculate of beef goats, compared with diets with no or lower coconut meal content. Diets with coconut meals may also enhance the semen quality of sheep.

1. Introduction

Livestock farming is a vital component of agriculture with the potential to promote the economic growth of both developing and developed countries, more so in developing countries. Livestock sustains the world population by providing various services and goods such as meat, milk, eggs, skin, and by-products [1].

Intensive farming refers to a method of food production that relies on intensification techniques. This farming system involves management practices and operations such as concentrated animal feeding, a large number of livestock raised in confinement at high stocking density, and use of selectively bred animals that grow more quickly than naturally occurring breeds and get large enough for slaughter in a shorter period [2]. The intensive livestock farming industry provides employment opportunities for millions of rural households, thereby helping reduce poverty in rural areas, especially in developing countries [2, 3].

By 2050, global livestock production is expected to double-growing faster than any other agricultural subsector, with most of this increase taking place in developing countries [4]. The expansion of the livestock industry may help meet the increasing demand for livestock products, especially in developing countries, which is adding additional pressure on the worldwide livestock farming systems [3]. However, the overall viability of the industrial livestock farming systems depends largely on animal performance and production efficiency, which are negatively affected by the scarcity and fluctuation in the quality and quantity of the animal feed supply. At a certain period of the year, the quality of grazing and browse deteriorates due to seasonal influences, resulting in a decline in animal productivity, unless supplements are provided for the animals [5]. Nonetheless, the conventional feeds commonly used to supplement ruminants are either not available or are available at a high cost, which means that strategies to make livestock farming more efficient to respond to the increasing demand for beef, milk, eggs, and other products are needed. One way to reduce the feeding costs without compromising the nutritional quality would be to use nonconventional feed resources such as by-products from agro-industrial processing and vegetable wastes that are locally available [6]. Many by-products used as alternative feeds are rich in fatty acids such as lauric, myristic, and linoleic, which may enhance productive animal performance [7].

During the dry season in tropical countries, especially in Africa, when only mature senescent material is available, both intake and digestibility are low. As a result, available nutrients do not meet the requirements of the animal, which compromise the animal’s ability to reach its genetic potential, unless the nutrient status is increased through supplementation using concentrates that supply primary nutrients such as protein, carbohydrate, and fat [8]. Thus, a better understanding of the quality of by-products and their use in animal feed may probably make livestock farming more efficient, especially in developing countries [9].

This chapter presents an overview of the intensive livestock farming systems in developed and developing countries and discusses the use of agro-industrial by-products as alternative sources of nutrients to improve livestock productivity, as well as the key nutritional components that are likely involved to improve the reproductive efficiency of animals.

2. Global overview of intensive livestock farming systems

Livestock farming throughout the world is becoming increasingly intensive as a result of the increased demand for beef, milk, eggs, and dairy by-products. The estimated population whose livelihood depends on agriculture makes up 42% of the total world population [10]. Therefore, this sector plays a vital role in the process of economic development of any country by ensuring a flow of essential food products, which contribute to food security. Also, livestock farming contributes draught energy and manure for crop production and appears to be the key food and cash security available to many people living in developing countries [4, 11].

It has been reported that the world’s population is expected to increase by 2% annually reaching 9.1 billion by 2050, while food demand is projected to increase by 59% in the coming decades. These projections challenge farmers to use proper methods, systems, and technologies to maximize productivity so that they can respond effectively to human consumption needs [12]. Since a majority of rural households live in areas where poverty and deprivation are the most severe and depend on agriculture for their survival, it might seem obvious that livestock needs to be intensive, modern, efficient, and competitive so that its contribution can reduce poverty and transform the economies of the countries [13]. Therefore, efficient and sustainable livestock farming systems in the whole world seem to be a priority for both small and large farmers [14].

Livestock farming worldwide is practiced in three different systems: extensive, semi-intensive, and intensive systems. In extensive livestock farming, mostly practiced in developing countries, the land is individually owned and the animals are heavily dependent on vegetation composed of wild plant species for grazing, which compromises the faster growth of animals and reduces their productive performance [12]. In this system, the animals are only brought indoors and fed meals during lambing and calving seasons or the winter. Although it is a less efficient system, it presents some advantages in terms of sustainability as it returns most of the animal manure directly to the soil, thereby contributing to increased crop production and nutrient cycling [11]. Also, animals can be raised in the semi-intensive systems, where they graze for some period during the day and in the evening, they feed on supplements. Both extensive and semi-intensive systems are practiced by smallholder farmers, and they are more suitable for ruminants such as cattle, goats, and sheep [15].

Currently, in the whole world, more so in developed countries, farmers are practicing intensive system-based management so that they can provide beef, milk, and eggs throughout the year. In this system, also described as factory farming, animals are enclosed in zero-grazing units where are fed and provided water to yield high productivity (beef, dairy produce, and poultry) from limited land available by raising large numbers of animals indoors. Under this system, diet, breeding, and disease are managed precisely and in consequence, meat, milk, and other products are produced in large quantities [16]. However, confined animals are usually fed based on concentrates composed of very expensive feedstuffs which makes this system the most expensive, requiring high initial costs to develop the activity [17]. One of the key strategies to make intensive livestock farming cheaper would be the adoption of food alternatives based on locally available and low-cost by-products such as coconut meal, palm kernel cake (PKC), palm fiber, cottonseed meal, and other vegetable and fruit wastes [18].

3. Alternative animal feeding for intensive livestock farming

One of the major constraints to livestock farming is the scarcity and fluctuation of the quantity and quality of the feed supply. However, it has been estimated that about one-third of the food produced globally for human consumption is wasted, representing a significant loss of the resources spent making and processing food and a threat to food security. The reduction of food waste is, therefore, a potential strategy for closing the gap between the supply and demand for food [19]. Moreover, competition between humans and animals for grains such as corn, wheat, bean, soybean, and others is increasing. Thus, it has become imperative to consider the use of food waste rich in protein, lipids, and some essential nutrients for animal health as feedstock in the animal feed industry [20].

Food waste is also referred to as a nonconventional feed resource, which is defined as feeds that have not been traditionally used in animal feeding and/or are not normally used in commercially produced rations for livestock. Some of such nonconventional feeds are agro-industrial by-products, which contain little economical value as foods for human consumption. In recent years, agro-industrial by-products have become major sources of dietary nutrients and energy in support of beef and milk production because they are available for use as livestock feeds at competitive prices relative to other commodities [21, 22]. Thus, the use of food waste for livestock feeding can help farmers reduce feed costs and help food waste generators reduce disposal costs while minimizing the environmental impacts of this waste [20].

In developing countries, the productivity of ruminant livestock has been constrained by the low quality of feed supply, since the basal diet of most cattle, sheep, and goats almost totally consists of roughage. Farmers often use high amounts of cereal grain-based concentrates for meat and milk production; however, this practice has introduced competition since grain is used for human consumption [23, 24]. Thus, providing adequate good quality feed to livestock to raise and maintain their productivity may be a major challenge to farmers all over the world. Future hopes of feeding millions of people worldwide and safeguarding their food security will directly depend on a high level of productivity, animal performance, and efficiency of the livestock farming, which may be reached through intensive animal farming that includes supplementary feeding plans based on by-products feeds [1].

In some developing countries in Africa, the farmers can neither spare land for feed production nor can they afford to buy expensive concentrates to feed animals. Therefore, efficient utilization of nonconventional feed for ruminants is a priority. For goats and sheep, supplementary feeding could be performed using crop residues, hay or silage for energy, protein concentrates, and agro-industrial by-products for additional protein [18]. So, it is important to support farmers with knowledge and technologies related to alternative feed resources that are easy to adopt and economically viable. To that end, studies were performed in Brazil to assess the nutritional composition of coconut meals and their impact on the reproductive performance of goats under the grazing system, and the results are discussed in the next section.

3.1 Nutritional composition of by-products used as alternative feeding for ruminants

The limited supply of nutritious feed is one of the main limiting factors to efficient animal production and reproduction. An intensive feeding system based on locally available by-product feeds may be an alternative promising feeding system to rear ruminants economically. However, the chemical composition of agro-industrial by-products may vary largely depending on the feedstock type (Table 1).

Agro-industrial by-products	Nutritional compositionz (%)							Reference
	DM	Ash	CP	EE	ADF	CF	NDF
Palm fiber	97.60	7.50	7.40	7.70	40.0	37.50	66.80	Padilla et al. [25]
	91.00	5.30	ND	2.69	54.80	ND	76.80	Obese et al. [26]
	95.30	5.30	15.12	3.98	25.30	ND	46.30	Chanjula et al. [27]
Chickpea	89.60	6.80	6.50	1.20	51.60	39.00	69.40	Bampidis et al. [28]
	89.30	3.30	21.90	4.00	4.80	ND	27.70	Serrapica et al. [29]
	91.10	2.85	22.50	5.09	ND	1.64	ND	Majewska et al. [30]
Soybean meal	93.85	5.70	44.56	5.69	7.35	5.60	13.84	NRC [31]
	88.87	6.39	51.41	3.45	10.13	6.18	12.22	Zambom et al. [32]
	87.9	7.21	54.30	1.32	7.00	ND	9.10	Harper et al. [33]
Orange pulp	22.10	ND	15.10	19.10	17.20	7.70	26.50	Minguez et al. [34]
	90.00	6.00	11.00	12.00	14.00	7.86	41.00	Watanabe [35]
Rapeseed meal	93.11	6.39	35.19	9.97	17.57	9.77	23.77	NRC [31]
	88.0	7.30	38.60	1.40	16.80	11.80	20.70	Feng and Zuo [36]
	88.70	ND	33.70	2.30	19.60	12.40	28.30	Maison [37]
Palm kernel cake	95.8	3.06	10.05	8.21	13.48	19.30	71.37	Mugabe et al. [38]; Suhaimi et al. [39]
	91.87	3.53	13.97	10.78	56.02	ND	64.09	Bringel et al. [40]
	95.29	3.33	16.64	7.78	45.71	ND	70.04	Oliveira et al. [41]
Cottonseed meal	90.69	6.39	39.22	5.50	17.92	13.96	25.15	NRC [31]
	94.50	7.51	24.28	7.94	31.80	ND	43.56	Tavares-Samay et al. [42]
	92.00	5.00	23.00	17.50	20.00	20.80	40.00	Blasi and Drouillard [43]
Apple pomace	92.35	ND	6.62	5.53	20.78	14.48	39.03	Xiong et al. [44]
	95.20	2.30	9.02	3.70	46.70	ND	61.20	Mirzaei-Aghsaghali et al. [45]
	88.84	6.10	7.70	6.18	43.20	51.10	68.50	Beigh et al. [46]
Coffee pulp	94.30	5.80	12.90	2.40	ND	14.60	37.20	Padilla et al. [25]
	69.16	16.6	18.12	5.71	ND	33.63	ND	Daniel et al. [47]
	88.69	8.42	12.58	2.65	77.84	ND	54.39	Barcelos et al. [48]

Table 1.

Chemical composition of different by-products from agro-industrial processing.

^z

DM, dry matter; CP, crude protein; EE, ether extract; NFE, nitrogen-free extract; CF, crude fiber; ADF, acid detergent fiber; NDF, neutral detergent fiber. ND, not determined. The values are presented as a percentage of the dry mater content.

Some nonconventional feeds such as coconut meal contain a crude protein ranging from 20 to 25% dry matter (DM) with relatively high quantities of cell wall constituents [neutral detergent fiber (NDF) more than 50% DM, and acid detergent fiber (ADF) of about 30% DM] [49]. Coconut meal obtained from mechanical extraction has generally high oil content (about 5 to 15% DM). This quantity of oil content makes it a valuable energy source for ruminants. An increase in the energy content of the diets through supplementary concentrate can potentially enhance milk production and improve growth rate, body weight gain, and reproductive performance [50, 51].

There are further feedstuffs also valuable as an alternative feed for ruminants, such as palm fiber, chickpea, orange pulp, rapeseed meal, cottonseed meal, and palm kernel cake (PKC), which because of its nutritional content may be described as an energy food. In addition, palm kernel cake supplies protein and energy but is usually classified as a source of protein, which may vary from 10.1 to 16.6% (Table 1). This protein content of PKC is regarded as sufficient to meet the needs of most ruminants [52, 53]. Proteins are the principal constituents of the organs and muscles and are required by ruminants for metabolic functions [38, 54]. Palm kernel cake also contains a large amount of crude fiber (CF; 19.3%), dry matter ranging from 91.9 to 95.8%, ether extract (EE; 7.8 to 10.8%), ash (3.1 to 3.5%), neutral detergent fiber (NDF; 64.1 to 71.4%), acid detergent fiber (13.5 to 56.0%) (Table 1), nitrogen-free extract (NFE; 46.7 to 58.8%), total carbohydrates (78.7%), nonfibrous carbohydrates (NFCs) (7.31%), hemicellulose (HEM) (25.98%), and lignin (4.28%) [38, 55]. The metabolizable energy (ME) of palm kernel cake for ruminants is 2.5 to 2.6 Mcal kg⁻¹, which is considered suitable for most ruminants [55].

Animals must be fed diets containing the earlier-mentioned essential nutrients for healthy growth and increased production. The ether extract is the main source of lipids which constitutes the principal component of sperm cells. It also stimulates cholesterol biosynthesis and testosterone secretion to sustain semen production in males [56]. Other fibrous components are sources of carbohydrates which are converted to acetic acids and used by the cows for energy and precursor of fat in milk [57]. It is also essential for animal health, since it is required by ruminants to support an appropriate rumen function and physiology [58].

3.2 Dietary effects on reproductive performance of ruminant livestock

The process of reproduction is aligned closely with the food supply. It is a coordinated function of many tissues, cell types, and regulatory systems which is possible only when animals are provided with sufficient quantities of dietary nutrients [59]. In tropical regions such as Africa, ruminants raised on smallholder farms face constraints of improper nutritional management, which may negatively affect their growth, health, and reproductive performance [60, 61]. For instance, puberty is usually delayed in grazing ruminants because grasslands in semiarid zones in the tropics do not provide enough protein and other nutrients, which leads to insufficient production of rumen microbial protein to support optimum growth rate [60]. Thus, nutrition plays a pivotal role in maintaining the body condition and reproductive efficiency of animals.

Nutrition consists of different nutrients such as protein, fat, carbohydrates, and micro-elements. Carbohydrates and proteins provide substrates for rumen fermentation, which results in the production of volatile fatty acids (VFAs). Ruminants utilize these VFAs as their main source of energy for maintenance, milk production, and reproductive performance. Malnutrition resulting from inadequate, excess, or imbalanced nutrient intake may lead to the loss of body weight. Low body condition delays the onset of puberty (up to 1 year in sheep and goats), reduces ovulation and lower conception rates, compromises embryonic and fetal survival, increases the postpartum interval to conception, interferes with normal ovarian cyclicity by decreasing gonadotropin secretion, increases the chances of infertility, and influences the rate of genetic progress [62, 63]. So, it seems to be clear that the initial reproductive events are sensitive to fluctuations in nutrient availability [61].

An inverse relationship between growth rate and age at puberty also exists in males. Low-quality feeding has been shown to delay puberty by about 5 months in bulls. The animals had poor testicular development and smaller ejaculates as compared to their normal counterparts. On the other hand, bulls kept on grazing plus concentrate feed showed a better growth rate than those on grazing only, with an earlier age at puberty and a greater scrotal circumference [60]. Even at maturity, the size of the testicles of underfed animals can be smaller [59] resulting in a lower sperm concentration in the semen. It has also been reported that the seminal vesicles contain less fructose and citric acid as well as smaller Leydig cells and seminiferous tubules and decreased testosterone levels under protein stress conditions [64]. Restriction of both protein and energy also prevented Merino lambs from reaching puberty in their first potential breeding season, with reduced testicular size and sperm quality in the ejaculate. Feed restriction also reduces libido in rams [60].

3.2.1 Effect of coconut meal on goat reproductive performance

To assess the effectiveness of coconut meal as an alternative feed and its effect on beef goats’ reproductive performance, a study was conducted in Brazil in 2016. Forty-eight males with initial body weight ranging from 26.04 to 28.54 kg were assigned in a completely randomized design into four groups with 12 replicates each under a semi-intensive system. The animals were kept indoors during the night and moved to graze in the morning on a pasture composed of Brachiaria decumbens (nonlegume forage plant). In the afternoon, the animals were supplemented with a concentrate containing 0% of coconut meal (group 1), 15% of coconut meal (group 2), 30% of coconut meal (group 3), and 45% of coconut meal (group 4) (Table 2). Before feeding the animals, the nutritional composition of coconut meal, soybean bagasse, corn meal, and pasture was assessed for dry matter, ash, ether extract, crude protein, neutral detergent fiber, total carbohydrates, hemicellulose, and lignin, and the results are shown in Table 3. In our study, coconut meal was included in four different levels (0%, 15%, 30%, and 45% of coconut meal) as a source of fatty acids and protein as well as a substitute for soybean meal, which is one of the most expensive feedstuffs in animal feed. In addition, the levels of cornmeal were also reduced while increasing the level of coconut meal. The animals’ body weight and testicular parameters were recorded every 15 days, and the semen was collected and assessed for volume, wave motion, progressive motility, sperm concentration, and sperm vigor according to the methodology suggested by CBRA [65]. In addition, the total number of sperm and the total number of viable spermatozoa were estimated according to the methodology described by Martin-Rillo [66].

Ingredients	Level of coconut meal (%)
	0	15	30	45
	g kg^−1 as fed
Coconut meal	0	150	300	450
Soybean meal	350	320	290	250
Cornmeal	600	450	350	250
Mineral salt	20	20	20	20
Urea	30	30	30	30

Table 2.

Level of coconut meal (treatments) in diet supplied to the goats.

Nutrients	Ingredients			Brachiaria decumbens
	Coconut meal	Soybean bagasse	Corn meal
		%
Dry matter	90.45	87.71	86.45	41.60
Ash	3.76	7.05	3.76	6.31
Ether extract	13.79	3.11	4.95	2.38
Neutral detergent fiber	58.46	57.60	30.69	52.01
Crude protein	23.57	46.38	6.74	7.48
Total carbohydrates	4.89	42.95	86.40	76.13
Hemicellulose	24.95	49.31	28.71	18.55
Lignin	16.21	2.96	1.47	3.09

Table 3.

Chemical composition of forage and feedstuffs used in concentrated feed for goats in 2016.

Source: Mugabe et al. (unpublished).

Our results showed an increase in the scrotal circumference and testicular volume of goats fed with concentrates containing 30% and 45% of coconut meal (Table 4). This result suggests that concentrates with high amounts of coconut meal may be more effective than those with lower amounts in improving goat’s testis. Also, the data in Table 4 suggest that scrotal circumference and testicular volume may increase as the body weight of goat increases, indicating a positive relationship between nutrition and goats’ testis size or reproductive efficiency. Males with a larger testis tend to produce more semen and offspring that reach puberty at an earlier age and release more ovules during each estrous period [68]. Oldham et al. [69] found that a 25% increase in testicular size led to an 81% increase in the production of spermatozoa. Also, Cameron et al. [70] found that an 86% increase in testicular size led to a 250% increase in the production of spermatozoa. The positive relation between testicular biometric parameters and body weight concerning nutrition effects was also reported by Martinez et al. [71].

Parameters	Levels of coconut meal (%)
	0	15	30	45
Initial body weight (kg)	27.38 ± 0.49	26.04 ± 57	27.50 ± 1.20	28.54 ± 2.41
Final body weight (kg)	35.10 ± 2.4^b	37.01 ± 1.1^b	45.02 ± 1.3^a	47.08 ± 2.6^a
DM intakeZ	113.49 ± 4^b	127.03 ± 4^b	159.10 ± 3^a	157.39 ± 8^a
Body score	3.20 ± 0.45	3.15 ± 0.20	3.70 ± 0.95	3.85 ± 0.65
Scrotal circumferenceY (cm)	25.29 ± 2.8^b	24.33 ± 3.9^b	36.40 ± 1.7^a	38.05 ± 1.2^a
Length of right testis (cm)	7.43 ± 1.39	7.81 ± 1.80	8.40 ± 1.53	8.11 ± 1.04
Width of right testis (cm)	4.89 ± 0.33	4.68 ± 0.81	5.20 ± 0.92	5.48 ± 0.99
Length of left testis (cm)	7.11 ± 1.43	7.90 ± 1.56	8.31 ± 1.00	8.05 ± 1.29
Width of left testis (cm)	4.19 ± 0.02	4.50 ± 0.63	5.10 ± 0.7	5.30 ± 0.42
Testicular volumeX (cm)	223 ± 109^b	249 ± 128^b	310 ± 104^a	342 ± 101^a
Testis shapeV	0.55 ± 0.0	0.58 ± 0.0	0.60 ± 0.0	0.59±0.0

Table 4.

Testicular parameters and initial and final body weight of goats fed coconut meal in 2016.

^Z

Dry matter intake (g/day).

^Y

Scrotal circumference was recorded using a measuring tape around the widest point of the testicles.

^X

Testicular volume (cm³) was estimated using the formula for a cylinder, where V=2× r² ×Π ×h; r = testis width/2; Π (Pi) = 3.14; h, testis length.

^V

The testis shape was recorded by the ratio between the width and length of the right and left testicles according to the methodology described by [67], which classifies testicles from long (ratio 0.5), long moderate (ratio 0.51 up to 0.625), long oval (ratio 0.626 up to 0.750), oval-spherical (ratio from 0.751 up to 0.875) to spherical shape (ratio equal or greater than 0.876).

Means followed by the same letters in each row are not significantly different at 5% by the Tukey test.

Source: Mugabe et al. (unpublished)

The diets with 30% and 45% of coconut meal showed higher levels of ether extract (Table 5) which is a saturated fatty acids source, such as lauric (C12:0), myristic (C14:0), palmitic (C16:0), and stearic (C18:0) acids and unsaturated fatty acids such as myristoleic (C14:1), palmitoleic (16,1), oleic (C18:1), and polyunsaturated fatty acids (PUFA) that include linoleic (C18:2) and linolenic (C18:3) acids, compared with other diets. So, it may be possible that the fatty acids in coconut meal may have increased the concentration of serum cholesterol which may lead to improved testosterone levels in goats. However, changing nutrition in small ruminants alters not only the total mass of testicular tissue but also the efficiency with which the spermatozoa are produced by that tissue [77].

NutrientsZ	Levels of coconut meal (%)
	0	15	30	45
		g kg^−1
Dry matter	710.38	718.40	739.02	741.38
Ether extract	42.50	43.28	51.39	56.19
Mineral matter	34.20	36.47	37.18	37.04
Crude protein	212.40	195.03	200.41	190.47
Neutral detergent fiber	240.60	320.31	345.02	380.58
Non-fiber carbohydrates	482.49	436.07	395.72	329.36
Total digestible nutrients	825.40	810.42	790.05	722.48
Cellulose	22.39	26.10	68.55	94.05
Hemicellulose	320.31	354.04	349.58	337.04
Lignin	52.30	67.54	86.22	92.30

Table 5.

Nutritional composition of the concentrates fed to goats in 2016.

^Z

Chemical analysis for dry matter (DM), mineral matter (MM), crude protein (CP), and ether extract (EE) was performed according to the procedure suggested by AOAC [72]. Neutral detergent fiber (NDF) was determined using the method recommended by Van Soest et al. [73]. Non-fiber carbohydrates (NFCs) were estimated using the following equation, as suggested by Hall [74]: NFC = 1000-(NDF+CP+EE+MM). Hemicellulose (HEM) and cellulose (CEL) were obtained by the sequential method, according to the methodologies recommended by Silva and Queiroz [75] using the following equations: HEM=NDF-ADF and CELL=ADF-Lig. (lignin), respectively. Total digestible nutrients (TDNs) were determined using an equation according to NRC [76]: TDN=87.84-(ADF × 0.70).

Source: Mugabe (unpublished)

It has been classically admitted that in both the mid and the long terms, variations in growth, testicle parameters, and fluctuations in live weight as a result of nutritional status affect also semen quality of ruminants, as nutrition appears to be the major modulator of sexual efficiency in small ruminants [71]. In our previous study with sheep managed under extensive range grazing conditions and fed with palm kernel cake as an alternative fatty acids source, it was observed that the diets affected sperm concentration of animals, more so diets containing 45% of palm kernel cake (Figure 1). Our results suggested positive relation between sperm concentration and nutrition, which means that animal feed supplementation is a key strategy to raise the reproductive performance of ruminants, as larger scrotal circumference, greater ejaculate volume, higher sperm concentration, higher daily sperm production as well as better seminal quality are strongly associated with nutritional management [38].

Figure 1.

Sperm concentration (×10⁹ mL⁻¹) of lambs fed diets containing levels of palm kernel cake. Source: Mugabe et al. [38].

In the current study, diets containing 30% and 45% of coconut meal improved sperm concentration per mL, total sperm number per ejaculate as well as sperm progressive motility when compared to the non-supplemented group (Table 6). Our results agreed with those of Santos et al. [78] who found that palm kernel cake and coconut meal affected positively the sperm concentration. Moreover, Rege et al. [79] found a strong influence of diets containing fatty acids source on sperm concentration. Depending on the age, genetics, and nutritional status, sperm concentration may vary from 1 to 3 × 10⁹ spermatozoa mL⁻¹ [80]. These results are similar to those observed in our study in which the sperm concentration ranged from 1.45 × 10⁹ to 3.55 × 10⁹ spermatozoa mL⁻¹.

Seminal parameters	Level of coconut meal (%)
	0	15	30	45
Volume (mL)	1.92 ± 0.45	1.87 ± 0.59	1.90 ± 0.3	1.96 ± 0.36
Mass motility (0–5)	3.00 ± 2.0	3.50 ± 1.0	3.00 ± 1.35	3.00 ± 1.00
Progressive motility (%)	60.4 ± 3.0^b	65.0 ± 4.0^b	80.5 ± 2.0^a	85.0 ± 0.0^a
Spermatic vigor (0–5)	3.00 ± 2.0	3.00 ± 1.00	3.00 ± 2.00	3.00 ± 0.00
Concentration (×10^9 mL^−1)	1.45 ± 1.0^b	1.75 ± 1.82^b	3.91 ± 2.47^a	3.55 ± 1.90^a
Total sperm/ejac. (×10^9)^z	1.39 ± 1.0^b	1.55 ± 1.93^b	2.90 ± 1.44^a	2.87 ± 1.47^a
Viable spermat./ejac. (10^9)^z	1.15 ± 0.5^b	1.20 ± 0.08^b	1.83 ± 0.37^a	1.95 ± 0.21^a

Table 6.

Physical parameters of the semen of goats fed with coconut meal under grazing in 2016.

^Z

ejac., ejaculate.

Means followed by the same letters in each row are not significantly different at 5% by the Tukey test.

Source: Mugabe (unpublished)

It has become apparent that reproductive efficiency depends on an adequate nutritional plan. However, other physical parameters of the semen of goats such as semen volume, mass motility, and spermatic vigor did not vary significantly with diets. Nonetheless, the findings from other researchers [81, 82] showed greater semen volume from lambs supplemented with a concentrate containing wheat bran, crushed maize, soybean meal, fish meal, salt, and vitamin-mineral premix than the control. These opposed results may possibly be related to the differences in the crude protein content of the concentrates used in the studies.

4. Conclusion

Intensive livestock farming may be a great strategy to ensure global food security and meet the increased global demand for meat, eggs, and dairy products. However, high operations cost, particularly related to animal feeding, compromises the expansion of this vital industry, especially in developing countries. The use of agro-industrial by-products may help reduce feeding costs without compromising the nutritional quality while reducing the risk of environmental pollution. However, by-products feeds vary largely in nutritional composition, with some containing high levels of crude protein, ether extract, and carbohydrates which have a significant influence on the growth and reproductive performance of ruminants. Diets containing 30 to 45% of coconut meal, rich in lipids and protein, may improve sperm progressive motility, sperm concentration per mL, total sperm per ejaculate, and total viable sperm per ejaculate of beef goats, compared with diets with no or lower coconut meal content. Diets with coconut meals may also enhance the semen quality of sheep. Thus, the use of coconut meal for animal feeding can make intensive farming systems more efficient by improving animal production and reducing feeding costs.

Acknowledgments

We acknowledge the financial support provided by the National Research Fund (Fundo Nacional de Investigação - FNI), and the Ministry of Science, Technology, and Higher Education of Mozambique through the Scientific Initiation Scholarships.

Conflict of interest

“The authors declare no conflict of interest.”