Effect of Supplementation of Ewes’ Diet with Date Waste and Saccharomyces cerevisiae on the Weight Performance and Growth Rate of Their Lambs ^†

Abstract

The aim of this study is to valorize agro-industrial by-products and to determine the effect of dietary supplementation with date waste and Saccharomyces cerevisiae on production performance, from late-gestation to lactation, of Ouled Djellal ewes and their lambs. The analysis of production performance data showed that there was no significant difference in the weight performance and growth rate of lambs born from ewes supplemented with different proportions of date wastes and Saccharomyces cerevisiae. It was revealed that the new-born lambs of ewes fed with date waste and Saccharomyces cerevisiae gave results close to or even better than those of lambs in the 33CON control group fed 100% concentrate, particularly 16REB and 25REB. This indicates that ewes were provided with their nutrient requirements for maintenance and production by substituting concentrate with this date by-product at 50% and 75%. Therefore, supplementation of pregnant and lactating ewes with date wastes and Saccharomyces cerevisiae seems to have a positive effect and could be employed as a partial alternative to concentrate.

1. Introduction

In Algeria, sheep farming (29 million head) remains a strategic sector for improving food security and the sustainability of animal production systems [1,2]. However, the feeding requirements for sheep to maintain good health and fulfil their potential have increased due to climate change, which has induced chronic and seasonal undernourishment and led to deficient productivity in this species. It is therefore necessary to evolve this animal production system and consider the substitution of sheep feed by the valorization of locally available agri-food by-products. The main advantages of this approach are a reduction in dependence of livestock on cereals consumable by humans and costs associated with waste management [3], and it is also an opportunity to reduce the high import costs that the state pays. In the case of date palm by-products, based on [4], the estimated tonnage of date waste represents an average of 25% of annual date production. According to [5], national date production is estimated to amount to 1,058,559 tonnes/year. Therefore, the estimated annual tonnage of date waste is 1,058,559 × 25% = 264,639.75 tonnes/year. From this quantity, it is evident that a very high tonnage of by-product is available from dates. In addition, date waste is rich in carbohydrates, fiber and minerals. Moreover, easily digestible sugars (fructose and glucose) are the main carbohydrates in dates [6], and due to its composition, date waste is a highly palatable and easily digestible feed; as such, it could be a valuable energy source and be used as a suitable supplement to low-quality roughages [7]. Consequently, date waste could constitute an important component of ruminant feed with a high energy value, which is interesting for lactating ewes, as we know that insufficient energy intake leads to reduced growth and reproductive performance [8,9,10,11]. However, these date by-products have a low crude protein content, requiring a protein supplement to balance the ruminant feed ration [12]. Several studies have investigated the addition of Saccharomyces cerevisiae as a feed additive to improve the ruminal microbiota of ruminants and, consequently, host health and performance when supplemented at sufficient levels [13,14]. Our work addresses concerns relating to the evolution of the animal production system through the substitution of Ouled Djellal ewes’ feed (concentrate) with date waste and Saccharomyces cerevisiae, determining the effect of this substitution on lamb weight and their average daily gain (ADG).

2. Materials and Methods

This research was carried out on the pilot farm “El-Baaraouia”, in the commune of El-Khroub, Wilaya of Constantine, Algeria. The experimental study was conducted on 30 pregnant ewes of the Ouled Djellal breed, multiparous and primiparous, aged 2 to 4 years, with an average weight of 62.92 kg ± 5.10 over a period of 120 days, including the adaptation period. The ewes were randomly divided according to the rations administered into 5 groups, each containing 6 ewes (

Table 1. Feed rations offered to ewes in experimental and control groups in percentages and grams.

	Rations	Concentrate		Date Waste		Wheat Straw		Saccharomyces cerevisiae (g/ewe)
		%	g	%	g	%	g
Control	Ration 33.33 CON	33.33	500	0	0	66.66	1000	0
Experimental	Ration 8.33 REB	25	375	8.33	125	66.66	1000	0
	Ration 25 REB	8.33	125	25	375	66.66	1000	0
	Ration 16.66 REBSC	16.66	250	16.66	250	66.66	1000	2
	Ration 16.66 REB	16.66	250	16.66	250	66.66	1000	0

). After parturition, their lambs were weighed at d0, d15 and d40 to evaluate weight performance and average daily gain after this substitution. The data obtained were analyzed by Statistica 2010 (One-Way ANOVA).

3. Results and Discussion

The results of the analysis of lamb weight performance according to the distributed rations are presented in

Table 2. Effect of supplementing ewes with date waste on lamb weight trends and the average daily gain.

Weight/ADG	8.33 REB	25 REB	16.66 REBsc	16.66 REB	33.33 CON	P
d0	4.90 ± 0.2	5.46 ± 0.38	5.19 ± 0.07	4.66 ± 0.34	5.53 ± 0.3	0.1708
d15	7.74 ± 0.56	8.22 ± 1.08	8.28 ± 0.21	8.60 ± 0.3	8.2 ± 0.4	0.8649
d40	11.64 ± 0.84	13.8 ± 0.26	11.81 ± 0.48	12.78 ± 0.26	11.36 ± 1.2	0.1883
ADG1(0–15 d) (g/d)	189.66 ± 35.99	183.77 ± 48.77	206.49 ± 13.38	262.22 ± 32.73	177.55 ± 21.78	0.4256
ADG2(15–40 d) (g/d)	156.10 ± 19.32	223.06 ± 49.75	141.10 ± 11.94	167.20 ± 17.75	126.66 ± 32.36	0.2072

. There was no significant difference between the different groups. Substitution of concentrate with date waste with and without SC resulted in similar body weights at parturition and at d15 to the 33 CON group, ranging from 4.66 to 5.53 kg at d0 and 7.74 to 8.60 kg at d15, with a slight increase in the weight performance of lambs from ewes ingesting the 25 REB ration (75% RD) at d40 (13.8 kg). Our results can be explained by [11], who assumed that the ewes in their study had an energy surplus which contributed to the constitution of their body reserves, also reflecting their production capacities; this had repercussions for lamb weight, given that the nutritional status of ewes at the end of gestation affects lamb birth weight.

Table 2 shows that there was no significant difference, with a relatively constant ADG, between the five groups, and a faster growth rate for the supplemented groups. In the second period (ADG2), 25 REB showed the highest ADG (223.06 g/d), which is comparable with the results of [8], who also revealed that the best ADG was recorded in the group containing 75% date waste. With the exception of the 25 REB group, a decrease in the ADG of all lambs was observed between the two periods, while superior lamb growth rates were still reported in ewes fed date waste. According to [12], the improved growth rate of supplemented groups could be explained by the presence of a series of digestive enzymes in date palm seeds. The addition of SC in ration 16.66 REBsc made this the second-best ADG in the first interval, but the result was not significant, which is in line with the results of [15,16], who reported a higher, but not significant, ADG for lambs fed probiotic-enriched rations.

4. Conclusions

The results of this study on the substitution of concentrate with date waste and Saccharomyces cerevisiae—in which the ingestion of date waste reached a value of 375 g/ewe/day compared with the control group, which ingested 500 g/ewe/day of concentrate—revealed that weight performance and growth rate of lambs of ewes fed either date waste and SC or concentrate did not vary significantly, and that these lambs gave results close to or even better than those of lambs in the 33 CON control group fed 100% concentrate, particularly the 16 REB and 25 REB groups. We can therefore conclude that date waste, a sustainable local resource treated as waste, can be used as an acceptable partial substitute in ewe feed, replacing expensive imported concentrate and helping to reduce the high food import bill that the state pays.