Feed preference, body condition scoring, and growth performance of Dohne Merino ram fed varying levels of fossil shell flour

Olusegun O. Ikusika; Conference T. Mpendulo

doi:10.1515/opag-2022-0161

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Feed preference, body condition scoring, and growth performance of Dohne Merino ram fed varying levels of fossil shell flour

Olusegun O. Ikusika und Conference T. Mpendulo

Veröffentlicht/Copyright: 12. Mai 2023

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Abstract

Acceptability of a diet is one factor that determines an animal’s growth performance. Some feed additives in the category of dietary clay, including fossil shell flour (FSF), have been identified to enhance performance of livestock. Therefore, the influence of varying inclusion levels of FSF supplementation on feed acceptability, body condition scores, and growth performance of Dohne Merino sheep was evaluated. Twenty-four Dohne Merino rams were completely randomised and individually housed in pens for 90 days. Four different supplementation levels of FSF (0, 20, 40, and 60g/kg) were considered treatments for the rams. The average daily feed intake, body condition score, average daily weight gain (g), and coefficient of preference were significantly higher in rams supplemented with 60 g FSF/kg than the other treatments (P < 0.05). The experimental diet colour was brown for 0 g FSF/kg, while in 20, 40, and 60 g FSF/kg, it ranged from light brown to slightly deep brown. The texture of diets with 0 g FSF/kg was moderately firm, while diets with 20, 40, and 60 g FSF/kg had a firm texture. The order of preference of diets supplemented with FSF in feed intake by Dohne Merino rams was: 60 g FSF/kg > 40 g FSF/kg > 20 g FSF/kg > 0 g FSF/kg. Therefore, FSF at a minimum inclusion level of 40 g FSF/kg can improve feed intake, body condition score, and feeding behaviour of Dohne Merino rams by increasing the acceptability of the diet.

Keywords: acceptability; Dohne Merino rams; feed preference; fossil shell flour

1 Introduction

In most tropical countries, livestock is reared chiefly under an extensive production system, mainly dependent on natural pastures for their nutrients [1]. The disadvantage of this kind of farming system is the scarcity of forage during the dry season, forcing the animals to partake in a greater quantity of low-quality forage [2]. This also compels the animals to consume a higher amount of less palatable species, which could result in a reduction of about 50% of the live weight gained during the wet season and, therefore, increases morbidity and mortality, leading to severe economic losses [3]. Furthermore, Kronberg and Malechek [4] and Homann et al. [5] reported a significant limitation on the domestic sheep’s productivity regardless of their potential to survive in natural forage.

Several feed additives have been employed to supplement poor-quality feeds for livestock, especially in the dry season. However, Villalba et al. [6] stated that some of these feed additives, because of different chemical and physical characteristics, could decrease feed intake due to a decline in appetite or liking of the consumed feed [7]. Intake of feed voluntarily is considered a significant indicator of feed quality. It is well recognised as a possible way to showcase animals’ performance [8]. Moreover, Dias et al. [9] and Li et al. [10] have reported that feed intake directly relates to the animal’s behaviour. Likewise, the diet's degree of preference and acceptability is important when determining the best feedstuff [11,12]. Feed intake is a function of the type of feed, its physical presentation, chemical composition, digestibility, and health of the animal, while the animal’s body condition score and performance depend on the feed intake, physiological, and sanitary stage. Since most animal performance indicators depend on feed intake vis-a-vis feed acceptance, farmers use several substances, including a chemical-based supplement (antibiotics), to boost animal diets’ palatability. However, this chemical-based substance has resulted in resistance to certain bacteria and negatively affects the final products from such animals [12]. Therefore, there is a need to use naturally occurring substances that can substitute chemical-based feed additives used in animal production to boost feed acceptance by animals. One such natural substance is fossil shell flour (FSF).

In recent studies by Chang et al. [13] and Koster [14], it was stated that FSF could be used as an animal growth promoter and natural anthelmintic, apart from being a mineral-rich additive and vaccine adjuvant in livestock. FSF is an organic, natural, sedimentary rock, which is rich in silicon and made up of fossilized relics of diatoms. Diatoms are hard-shelled plant algae that accumulated on earth from seas and lakes a long time ago when they dried up [13,14]. This substance is available to and affordable by poor resource farmers, and is nontoxic [15]. Therefore, the current study aimed to investigate the effect of FSF inclusion on body condition scoring, feed preference, and growth performance of Dohne Merino rams.

2 Materials and methods

2.1 Study site

The study was conducted at the University of Fort Hare, Honeydale Research farm, Alice, Eastern Cape Province, South Africa. It is situated at 32°46′S and 26°50′E, at 535 m above sea level. It has an approximate 24.6, 11.1, and 17.8°C maximum, minimum, and average temperature. The area’s annual rainfall is 575 mm, often from November to March, also referred to as the summer months. The area is mainly dominated by grass species, including red oats grass and Cympogon plurinodis, and woody species like Acacia karroo and shrubs invading the foraging lands [16].

2.2 Management of rams, feeding, and experimental design

Twenty-four Dohne Merino rams aged 5–6 months, averaging 19.8 ± 0.43 kg, were used in the experiment and housed independently in pens. A completely randomised design was used in the study; it comprised four treatments with six rams in each treatment. 2 mL of Maxicare was used to drench each animal to control gastrointestinal nematodes. This was done using a drenching gun. The animals were housed under average environmental conditions, housing, and equipment facilities. They were kept in pens of 1.5 m × 1.5 m individually, the building was roofed, and the pens were well-ventilated. Each pen had a concrete floor. The temperature (23.29°C), relative humidity (76.75%), dry-bulb temperature (24.82°C), and wet-bulb temperature (21.15°C) were similar in the pens. The experiment duration was 90 days, not considering 14 days of the adaptation period. All animals had access to fresh water ad libitum.

Ethical approval: The research related to animal use has been complied with all the relevant national regulations and institutional policies for the care and use of animals, and was approved by the University of Fort Hare, Animal ethics and Use Committee (Approval number: MPE041IKU01).

2.3 Experimental diets

Experimental diets are presented in Table 1. Concentrated ingredients were bought at Monti Feeds (Pty) Ltd in East London, South Africa, whereas Eragrostis tef and Medicago sativa were purchased from Umtiza Agricultural Products (Pty) Ltd, Kwantu shopping mall, Alice, South Africa. Each ingredient was milled and mixed evenly together to form the basal diet. Diets were formulated to meet the sheep’s dietary (energy and protein) needs [17]. The four treatment groups were basal diet (0 g/kg FSF), basal diet + 20 g/kg FSF, basal diet + 40 g/kg FSF, and basal diet + 60 g/kg FSF. The feed was administered to the rams at 8:00 h and 15:00 h at 3% animal’s body weight (BW; dry matter (DM) basis) according to NRC [18]. Food-grade FSF was brought from Eco-Earth (Pty) Ltd in Port Elizabeth, South Africa. The company holds a licence from the Department of Agriculture, Forestry, and Fisheries of South Africa to produce the product.

Table 1

Composition of experimental diets (DM%)

Ingredients	0 g FSF/kg	20 g FSF/kg	40 g FSF/kg	60 g FSF/kg
Maize	8	8	8	8
Sunflower oil cake	10	10	10	10
Molasses	5	5	5	5
Wheat bran	15	15	15	15
Limestone	1.6	1.6	1.6	1.6
Sheep mineral-vitamin premix	0.20	0.20	0.20	0.20
Salt	0.30	0.30	0.30	0.30
Ground Lucerne hay	30	30	30	30
Ground teff hay	30	30	30	30
FSF	0	2	4	6

2.4 Measurements

2.4.1 Feed intake and growth performance

Throughout the experimental phase, all data on the amount of feed given and consumed by the animals and the equivalent orts (leftover) were recorded daily to evaluate DM and nutrients’ voluntary intake. Samples of feed offered and orts were oven-dried at 65°C until constant weight to determine the dry matter content. It was then ground to pass through a 1 mm sieve (Wiley mill; Thomas Scientific, Philadelphia, PA, USA) and examined to determine the organic matter (OM), crude protein, ether extract, and crude fibre-based on the techniques by A.R.C. [19]. At the start of the trial, each animal’s BW was measured weekly during the feeding trial and at the end of the feeding period in the morning before feeding. The acquired data were used to calculate the feed intake, average daily gain, and feed.

2.4.2 Body condition score (BCS)

The BCS was taken every week prior to feeding by skilled personnel. The BCS chart used centred on the method described by Association of Official Analytical Chemists [20] and Khan et al. [21]. This method has 0.5 intervals for scores ranging from 1 (emaciated) to 5 (obese). The scores were awarded based on the muscling and fat deposited in the loin region of the animal.

2.4.3 Feeding behaviour and coefficient of preference (CoP)

Feeding behaviour (time spent on feeding, TSF; number of visits, NV; and total bites per visit, NBV) of 24 Dohne Merino ram were video recorded for 6 h each day during a feed preference test with a digital camera for 21 days, excluding 7 days for adaptation. The digital video camera was located on the pens’ top view, where clear and adequate footage of each ram was obtained. Each pen contains four feeding troughs with identification and is equally spaced by 0.7 m from one another. Each ram was allowed access to feeding troughs for 6 hours every day for 21 days. The feeding troughs’ position was interchanged daily to prevent the animals' bias and conditioning in recognising part of the pen for a particular diet [20]. Filmed feeding behavioural footage was analysed by two trained observers to classify feeding behaviour’s visual observations. At the end of 6 h, each feed not consumed was evaluated by subtracting leftovers from the amount of feed presented to the animal. The CoP was evaluated as the proportion of diet consumed by an individual to all the diets’ standard intake. The percentage of preference was determined as the proportion of feed consumed by an individual to the total intake multiplied by 100. Diet was regarded as satisfactory when CoP is more than one, while ranking was based on the preference percentage [21,22].

2.4.4 Diets evaluation

According to general procedures, the diets’ physical characteristics (colour, smell, and texture) were assessed [17]. The diet colour was considered using a colour chart, while nine trained panellists judged the diets’ smell and texture. Table 2 shows the scale (0–5) that was used.

Table 2

Experimental diets score (0–5 scale*) based on physical characteristic

Parameters	0 g FSF/kg	20 g FSF/kg	40 g FSF/kg	60 g FSF/kg	SEM
Colour	4.61^c	5.64^b	5.71^a	5.72^a	0.02
Smell	4.03^c	4.42^b	5.01^a	4.43^b	0.02
Texture	3.03^d	4.02^c	5^a	4.23^b	0.01

*0 – very bad; 1 – bad; 2 – going bad; 3 – moderate; 4 – good; 5 – excellent. a,b,c – mean values with different superscripts on the same row differ significantly (P < 0.05).

2.5 Data analyses

The data for feed intake, body condition scoring, CoP, physical characteristics of diets, and behavioural patterns of rams were analysed using the General Linear Model procedure of SAS (2010). The significant means were separated using Duncan’s Multiple Range Test.

3 Results

3.1 Feed intakes, growth performance, and CoP

Table 3 indicates that the addition of FSF in Dohne Merino rations had a significant effect (P < 0.05) on feed intake. As the inclusion levels increase, average daily feed intake, average daily weight gain, and CoP increase. Rams provided a diet with 40 and 60 g/kg of FSF ingested more feed than the control group and rams supplied with 20 g/kg of FSF. The CoP was highest in rams supplemented with 60 g FSF/kg (P < 0.05) and lowest in the control. The order of preference was: 60 g FSF/kg > 40 g FSF/kg > 20 g FSF/kg > 0 g FSF/kg.

Table 3

Preference of Dohne Merino ram for FSF

Parameters	0 g FSF/kg	20 g FSF/kg	40 g FSF/kg	60 g FSF/kg	SEM
Average daily feed intake (g)	480^d	495^c	530^b	588^a	13.20
Feed efficiency	0.16^b	0.17^b	0.21^a	0.21^a	0.01
Average daily weight gain	79.55^c	85.95^c	109.05^b	122.08^a	7.03
Total weight gain (kg)	7.08^c	7.16^c	9.20^b	10.3^a	0.85
CoP	0.60^d	0.89^c	1.03^b	1.48^a	0.03
% Preference	15.08	22.15	25.85	36.92
Preference ranking	4th	3rd	2nd	1^st
BCSs (units)	2.87^b	3.1^a	3.13^a	3.25^a	0.07

a,b,c – mean values with different superscripts on the same row differ significantly (P < 0.05).

3.2 Body condition scoring

A direct relationship between the body condition scores and growth performance was observed, as illustrated in Table 3. Inclusion levels of FSF in rams’ diets significantly affected the rams’ body condition score (P < 0.05). Rams with FSF-supplemented feeds had higher BCS than those without FSF supplementation (P < 0.05). Rams fed with lower inclusion levels of FSF had lower BCS values than those provided with 60 g/kg FSF (P > 0.05, Table 1).

3.3 Physical characteristics of diets

Table 4 shows the implication of FSF’s colour, smell, and texture on the diets. The colour of experimental diets varied from light brown to brown. The treatment with 0 g FSF/kg was brown, whereas treatments with FSF supplementations were light brown. A significant effect was not noticed (P < 0.05) among the smell of the experimental diets. The treatments’ texture was moderately firm in the non-supplemented diet, while all the supplemented diets had a firm texture. Table 2 shows the physical characteristics of the experimental diet. Among the scores of the colour, the statistical effect was not observed (P < 0.05), where 40 and 60 g FSF/kg showed the highest values with the scores of the smell, the scores of the texture were higher in 40 g FSF/kg than other treatments.

Table 4

Physical characteristics of dietary treatments

Parameters	0 g FSF/kg	20 g FSF/kg	40 g FSF/kg	60 g FSF/kg
Colour	Brown	Light brown	Light brown	Light brown
Smell	Pleasant	Pleasant	Pleasant	Pleasant
Texture	Moderately firm	Firm	Firm	Firm

3.4 Feeding behaviour of rams

Table 5 shows the ram’s feed preference. The ram’s NV, NBV, time spent on a visit (TSV), and dry matter intake (DMI) were higher (P < 0.05) in rams with rations supplemented with FSF compared to without FSF supplementation. Leftover feed was more in rams fed with the diet with 0 g FSF/kg than those provided with FSF-supplemented diets (P < 0.05). Dohne Merino showed a significant difference (P < 0.05) in rams supplemented with FSF behavioural patterns.

Table 5

Behavioural patterns exhibited by Dohne Merino rams fed with FSF

Parameters	Treatments				SEM
Parameters	0 g FSF/kg	20 g FSF/kg	40 g FSF/kg	60 g FSF/kg
NV	2.96^d	3.96^c	4.64^b	6.75^a	0.455
NBV	3.17^c	4.43^c	8.00^b	11.54^a	0.889
TSF	1.96^c	2.89^b	3.36^b	4.82^a	0.27
FR	381.18^a	363.14^ab	354.54^b	328.68^c	6.751

NV – number of visits; NBV – number of bites per visit; TSF – time spent on feeding; FR – feed remaining; SEM – Standard error of mean.

a,b,c – means with different superscripts on the same row differ significantly (P < 0.05).

4 Discussion

The lower feed intake in treatment provided 2% of FSF compared with the value obtained for the 6% FSF inclusion level recorded by Ogunbosoye [23]. Using West African Dwarf Sheep was similar to the results obtained in the present study. Similarly, this result agreed with statistical variations observed in calves’ feed intake fed with varying FSF levels, as reported by Babayemi [24]. The requirement of sodium chloride (NaCl) for sheep per day per head is about 25–40 ounces. McLean et al. [25] and Digby et al. [26] observed that sheep consumed less feed when it lacked NaCl. Likewise, studies show that minerals, including sodium, calcium, potassium, and magnesium, improve the diet palatability and intake of feed by animals [27,28]. These minerals in FSF could be the reason for rams provided with FSF-supplemented feeds in this experiment had higher average feed intakes than the control. This is due to the findings that FSF had been described to have a lot of minerals, such as sodium (923 ppm), calcium (0.22%), magnesium (0.11%), and potassium (0.11%) [29,30,31].

In ruminants, fat reserves could be predicted by the BCS values of such animals. The BCS increased from 3 to 4 or 4 to 5 units, increasing muscle mass [32]. Different researchers have observed a positive correlation between weight gain and BCS. However, the animal breed could result in weight gain variations as BCS increases [22]. The body condition scores of the rams supplemented with FSF were different (P < 0.05) from the ones not supplemented in the present study, which aligned with the trend reported by Kenyon et al. [22]. There are energy costs for both live weight gain and BCS. Therefore, it implies that rams fed with FSF-supplemented feeds would have more reserved energy for production, metabolism, and physiological purposes than those fed with FSF non-supplemented feeds. The CoP likewise increased as the inclusion levels increased, and there was a significant difference in the CoP values across all treatments. Chay-Canul et al. [33] and Van Burgel et al. [12] observed that an increase in the CoP and feed intake have a linear relationship, which agree with the present investigation outcome. Fadayifar et al. [34] stated that the CoP is directly proportional to the diet’s nutrient composition, especially the minerals and vitamin content.

The current study results showed that Dohne Merino rams’ feeding behaviour was influenced by FSF supplementation in the diets. The rams preferred and accessed diets supplemented with FSF compared with non-supplemented FSF diets. The number of visits improved when the concentration of FSF increased in the experimental rations. This could explain why the sum of bites per visit (NBV) and the DMI in rations supplemented with FSF was statistically higher than FSF non-supplemented diet. Slamova et al. [35] reported that the richness of some dietary clays, including FSF and bentonite in minerals, could increase livestock palatability. This further strengthens the outcome in the present research that FSF is rich in minerals (Table 6). Therefore, the surge in the NV and the by the rams in diets supplemented with FSF could be attributed to the excellent taste brought about by FSF, as it is rich in sodium, calcium, potassium, and magnesium. Martin [36], and Villalba et al. [37] stated that sodium in the form of NaCl animal diets affects their feeding behaviour through the taste and aroma of the diets. Silva [38] and Ilori et al. [3] noted goats with free access to feed would show a variation in feed intake depending on the nutrients available from the feed. The current study revealed that Dohne Merino rams exhibited less acceptance for 0 and 20 g FSF/kg. This may be associated with the relatively low mineral value in the control diet since it lacks silica which is contained in FSF [39].

Table 6

Proximate analysis of the experimental diets

Items	Percentage
Maize	8
Sunflower oil cake	10
Molasses	5
Wheat bran	15
Limestone	1.6
Sheep premix	0.2
Salt	0.3
Grinded leucine hay (alfalfa)	30
Grinded teff hay	30
Chemical composition
DM (% as fed)	95.5
OM	85.22
Energy ME	24.67
Crude Protein	14.56
Ash	10.33
Ether extract	1.7
Crude fibre	22.60

The feed’s colour, smell, and texture did not differ during the visual inspection. While colour ranges from light brown to brown, smell ranges from pleasant to very pleasant, and texture varies from moderately firm to firm. However, the differences in the smell, colour, and texture might not have been different to the extent of causing any difference in feed and feed intake preference due to the slight difference. Moreover, it must be considered that the pattern of feed intake and preference noted in this research for the DMI and percentage of preference did not correspond with the variations observed in the smell, colour, and texture attributes. The current observations are similar to the results obtained by Brand et al. [40]. They noted that the feed intake of grower ostriches fed with different inclusion levels of Lupinus angustifolius was not affected by the feed colour. Therefore, it is relatively unclear whether the feed’s smell, colour, and texture impacted the feed intake and preference of the rams. Still, it should be noted that some other elements apart from the physical characteristics of diets might have caused a significant influence on regulating feed preference. The current study outcomes align with the research conducted by Brand et al. [40]. They noted that the physical characteristics of feedstuff did not influence the preference for green plastic strips. However, the results differ from the findings of Bubier et al. [41], which indicated that feed colour impacted feed intake and preference in chickens. Forbes and Covasa [42] suggested that feed intake in a system with unlimited access to feed relies on the livestock’s physiological state or metabolic requirements and can also be influenced by factors that include previous experience and social interactions. Many researchers [42,43] noted that the feed’s form, type, and nutrient content greatly impact the diet preference. Brand et al. [40] noted that factors such as breed, treatment design, feeding equipment, genetics, and management position might also contribute to diet selection by livestock. However, in the current study, grass hay was the only constituent of the feed to which the rams had access before. Moreover, all other aspects that could impact feed preference were rendered stable and the same in all pens to prevent the danger of any outside influences on feeding behaviour.

5 Conclusion

The current study showed that FSF could improve feed acceptability and growth performance of Dohne Merino rams with 40 and 60 g FSF/kg inclusion levels giving optimum productivity. Therefore, FSF can boost Dohne Merino rams’ production output by increasing acceptance of feed vis-à-vis performance.

Acknowledgments

The authors acknowledged the efforts of the staff in the Department of Livestock and Pasture Science, University of Fort Hare, for their support. The article based on a preprint published in Researchsquare depository, available at link: https://www.researchsquare.com/article/rs-31728/v1.

Funding information: The research was sponsored by the South African Medical Research Council (Grant number SAMRC/UFH/P790).
Author contributions: O.O.I. conducted the experiment as part of his PhD research; C.T.M. supervised the study.
Conflict of interest: The authors state no conflict of interest.
Data availability statement: The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

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Received: 2022-06-09

Revised: 2022-11-19

Accepted: 2022-12-03

Published Online: 2023-05-12

This work is licensed under the Creative Commons Attribution 4.0 International License.

Artikel in diesem Heft

https://doi.org/10.1515/opag-2022-0161

Schlagwörter für diesen Artikel

acceptability; Dohne Merino rams; feed preference; fossil shell flour

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