In the present study, White Fulani (WF) produced higher milk yield (1.
16kg/day, P<0.001), fat yield (53.97g/day, P<0.01) and protein yield (41.67g/day) than Borgou (BO) breed.
These results are similar to those reported by Houaga et al. (2017) in the same breeds. Only fifteen FAs were identified in milk fat of BO and WF cattle breeds in the present study which is lower than the reported 30 FAs identified in Longissimus thoracis muscle of BO and WF in Benin (Salifou et al., 2013). The small number of FAs identified in this study may be partly explained by the absence of the other FAs or their presence at a very low concentration to be detected by the GC-MS. In the present study, significant differences between breeds were observed for individual fatty acids, fatty acids unsaturation indices and FA groups. BO breed showed milk with higher MUFA, PUFA, C18 and total indices than WF. Breed effect on FA composition was reported in meat of Borgou and White Fulani cattle in Benin (Salifou et al.
, 2013), in milk of South African indigenous cattle breeds (Myburgh et al., 2012) and Italian Holstein-Friesian, Brown Swiss, Simmental and Alpine cattle breeds (Gottardo et al., 2017). In this study, WF presented the highest content of SFA (68.19 vs. 58.46%, P<0.001) and the lowest PUFA (12.
40 vs. 19.56%, P<0.001) compared to BO, with no significant difference for MUFA (19.41 vs. 21.
98%, P>0.05). These results corroborate the previous study in Benin indicating that the WF bulls presented meat with higher SFA (49.68%) compared to BO (43.03%) and similar contents (33.
60% vs. 33.43%) in MUFA (Salifou et al., 2013).
The authors postulated that the high content of SFA in WF meat can be explained either by the higher volume of its rumen compared to BO breed or most acetic fermentation and the poor quality forage (Salifou et al., 2013). The Borgou presented higher C18 index (P<0.001) and total unsaturation index (P<0.05) than BO. The unsaturation or desaturation index of a specific FA represents the ratio of the concentration of the monounsaturated product to the sum of the monounsaturated and the saturated substrate.
Considering human health aspects, increasing the amount of unsaturated FA as well as unsaturation indices is an important selection objective (Schennink et al., 2008). BO presented lower SFA (58.46%) than the values of 64%, 63.
7%; 60.9% and 71.9% reported in milk of free-ranging South African indigenous Boran, Nguni, Tuli and Afrikaner cattle breeds, respectively (Myburgh et al., 2012). Moreover, BO and WF presented lower MUFA content (21.98% and 19.41%, respectively) than the South African indigenous with MUFA ranging from 25.
7% in Afrikaner to 36.5% in Tuli breed (Myburgh et al., 2012). On the contrary, BO and WF produced milk with linoleic acid (C18:2 cis-9, cis-12) of 15.
84% and 9.85% respectively , much higher than the range of 1.3 to 1.7% observed in South African indigenous Boran, Nguni, Tuli and Afrikaner (Myburgh et al., 2012).
The great difference in linoleic acid content in BO and WF in the present study compared to the South African indigenous cattle may be due to the lower sample size in their study being 6 Boran, 9 Nguni, 10 Tuli and 6 Afrikaner (Myburgh et al., 2012). Several factors influence milk FA composition and the most important being species, breed, individual variability and feeding (Poulsen et al., 2012), stage of lactation, parity number and season (Gottardo et al.
, 2017). The cows included in the present study were raised in the traditional system on natural grazing without feed supplementation and they were sampled at the same period eliminating the season effect. The observed difference between breed would therefore be due to their genetic background. However, the difference in FA composition between the two breeds could also be due to the FA composition of the forage consumed by the cows on natural grazing. The WF and Bo are raised in different agro-ecological with different floristic composition.
The WF cattle are found in the Northern part while BO cattle are found throughout the country. The forage species and variety, climate, fertilization and stage of growth are important factors that affect fatty acid content and composition of forage (Kala? and Samková, 2010) and can therefore affect the milk FA composition of the cows. The BO cows from North-Benin produced milk with higher C14:1 cis-9, C18:1 cis-9, C14 index, C18 index, total index and MUFA contents than BO cows from South-Benin. This geographical region effect could be explained by the differences in plant species and variety, climate, rainfalls and stage of growth of the forage grazed on natural pasture in the two regions (Kala? and Samková, 2010; Salifou et al., 2013)