Palm dates as an additive to improve the nutritional value of ryegrass and brassica-based silages before their use to improve degradability, microbiome and performance of ruminant animals.

Abstract

Abstract: Ten replicated studies evaluated Seedless Whole Date Palm (SWDP) as an energy rich additive to two contrasting forages to improve the ensiling process, chemical characteristics in vitro dry matter degradability (DMD), the rumen function and the performance and rumen microbiome of growing lambs. This was achieved by conducting a series of in vitro and in vivo experiments where, firstly, five brassica hybrids comprising rape-avon (Avon), stubble turnip (Vollenda), brassica-redstart (Redstart), brassica- swift (Swift) and their mixture (Mixed) were tested for their production potential, nutritive values and DMD. Secondly, the effects of adding four doses (0, 5, 10 and 20%) of SWDP to the 2 selected brassica (Avon and Swift) and Ryegrass forages on their nutritional values after wilting and ensiling were evaluated. Finally, a trial with live lambs was conducted to evaluate the effects of SWDP addition at 0 and 20% in wilted Ryegrass and Swift on the silage quality, feed intake, growth performance, carcass weight, long chain fatty acids, lamb behaviour, IVDMD and rumen microbial profiles. Results confirmed that the addition of SWDP significantly decreased the crude protein (CP) and Oil-A contents (P<0.01 and P<0.01, respectively) of ensiled forages. There was an interaction between silage type and SWDP for their effects on D-value, metabolizable energy (ME), CP, Oil-A (ether extract, EE), neutral detergent fibre (NDF), and lactic acid (P<0.01, P<0.01, P<0.01, P<0.01, P=0.02 and P<0.01, respectively). The addition of SWDP linearly increased D-value and ME contents (P<0.01 and P<0.01, respectively) in the ensiled forages. There was also a significant difference between the five wilted brassica varieties for their mean DMD values (P<0.01). Moreover, the addition of SWDP showed significant differences between the wilted forages for the mean DMD (P<0.01), where the wilted forage x SWDP interaction was significant (P<0.01) for DMD. There was a linear increasing effect of increasing the SWDP addition from 0 to 20% on the DMD of both wilted and ensiled forages (P<0.01). The feed conversion ratio (FCR) (kg DM/kg gain) of 9 was the lowest for lambs fed Swift with SWDP at 0% compared with 13 for Swift with SWDP at 20%. It can be concluded that the ensiled Swift with SWDP at 0 and 20% were better for lamb feeding than Ryegrass at 0 and 20% in term of average daily gain (ADG) and FCR. Based on the in vitro DMD results, it is concluded that the addition of SWDP at 20% did show a positive response when compared with the 0% addition (P<0.01), but Ryegrass responded more to the added SWDP than the Swift to improve DMD. The DMD values of 75.4 and 77.2%, respectively, in Swift at 0 and 20% SWDP were higher than the corresponding values of 47.3 and 57.7%, respectively for Ryegrass at 0 and 20% SWDP. Regarding the microbiome analysis, the Firmicutes and VI Bacteroidetes were the dominant phyla in the rumen fluid (RF) of the trial lambs. Conversely, the Prevotella, Selenomonas, Fibrobacter and Bacteroides genera were abundant in lambs depending upon the ensiled forage type containing the added SWDP. The greater dominance of Bacteroidetes in Ryegrass based RF was perhaps due to its higher NDF content than the Swift based RF. Indeed, the abundances of Firmicutes, Bacteroidetes and Fibrobacteres phyla were increased and those could be used as indicators of increased fibre and protein degrading microbes in the RF of lambs fed Ryegrass-based diets. Keywords: Date palm; Brassica; Ryegrass; Silage; Degradability; Lamb; Microbiome