The study was conducted in Al-Newala Village south ELObied town, Sheikan locality in North Kordofan state, Sudan. The milk production and composition of desert goats fed varying levels of baobab (Adansonia digitata) seed cake supplement was investigated over a period of 135 days. Twenty-four (24) adults pregnant does of Desert goats were randomly allotted to four dietary treatments with six animals per replicate in a completely randomized design to determine the quantity and quality of milk produced. The does were of similar initial body weight. They were randomly assigned to four supplementary feeding treatments. Group A was used as a control (un supplement as in farmer practice), the second group B was supplement with diet of 65% baobab seed cake, group C with diet of 55% baobab seed cake and group D was supplemented of 45% baobab seed cake. All does in all groups were subjected to natural grazing. The results indicated that supplementation with baobab seed cake had a highly significantly (P<0.05) effected milk production on 90 days, total milk production and daily milk yield. The does in group B had registered highest significantly (P<0.05) more milk (116.92 Lb) than those in group C and D as 114.15 Lb and 107.97 Lb respectively. The least milk was produced by the A group (control) of (79.73Lb) and which was significantly (P<0.05) less than supplemented groups. The daily milk production indicated that the does supplemented with baobab seed cake yielding significant (P<0.01) higher milk than control groups as 0.88,1.30, 1.27 and 1.20 Lb for group A, B, C and D respectively. The data indicated that supplementation had exerted a significant (P<0.05) effect on fat during 605-90 days with higher fat percentage in group C in 30-60 days as 3.75% and group D as 3. 57%. Protein % showed significant (P<0.05) effect during 0-30 and 60-90 days, where high percentages were in group C with 3.77%. Lactose and as content secured non-significant effected by baobab seed cake supplementation. In conclusion supplementation with baobab seed cake diet to Sudanese Desert goats during dry season improved milk production and inclusion of baobab seed cake at 65 % in the diet of Desert goats gave the highest milk yield.

Goat production plays a very vital role in the livelihood of rural populations in Sudan as it contributes significantly to improvement of family nutrition and health. The Desert goat is indigenous goat breeds found in western Sudan. Records of its dairy performance in the natural environment it produces a low quantity of milk when compared with other goat breeds [1]. The nutritional role of milk and milk products in human diet is well documented [2]. Milk from ruminants is a good alternative to augment animal protein intake.  Increased awareness of the importance of milk in tropical areas has led to increased demand for milk and its products [3]. The rising demand for milk and its products in the tropics has made it imperative to find means for increasing local milk production, even outside their natural habitat/environment; this practice helps in performance evaluation of animals in locations outside their domain [4]. 

Milk quality and quantity is very dependent on the type of feed used in farming [5]. Generally, farmers in Sudan have minimal sources of feed for their domestic animals. Feeding system mainly depends on the use of forage, native grasses, legumes and field grass originating from the surrounding environment with limited sources and low nutritional quality (protein content) affect productivity.  Under such systems livestock production is constrained by scarcity and fluctuating quantity and quality of the year-round feed supply during the dry season [6 -7]. As a result, animals consume higher quantity of less palatable species and protein content, which consequently results in loss of body weight and low milk production. In order to maximize opportunities presented for milk production by goats, so it is significant to improve the quality of feed and explore new kind feed sources to increase the quality of milk. [8].

Promotion of concentrate feeding to improve low quality dry season feeds is limited by high competition with humans as well as soaring cost. It was reported that high competition for consumption of conventional protein sources between human beings and the livestock industry in the last two decades has resulted in an inadequate supply of dietary proteins [9]. Feeding of ruminant livestock generally becomes a challenge to farmers during dry season but due to their small herds the small scale farmers are the hardest hit given the high feed costs, especially energy and protein sources. So it is significant to improve the quality of feed and providing adequate good-quality feed and explore new kind feed sources to increase the quality of milk and maintain their productivity while mitigating climate change [8]. The problem of feed shortage can be addressed by the use of locally produced good quality alternative non- conventional feed materials which are nutritious and affordable [10].  Therefore, there is a need to exploit non-conventional protein sources. Research on low-cost and locally available indigenous protein sources is very important, especially those which do not attract competition with human beings and the ever-expanding intensive livestock production. The use of local indigenous multipurpose tree products and by-products, such as seed cakes and leaf meals is one such possible alternative. Utilization of non-conventional feedstuffs especially when it encourages a shift to other ingredients that are not edible to man but readily available will reduce the cost of feed and maximize the returns from small ruminant production [1].

Reports have indicated that one of the potential low-cost and locally available protein sources in small ruminant diets is Adansonia digitata (baobab) seed [11]. Baobabs trees are widespread all over the hot, drier regions of tropical Africa and are prevalent Sudan and are commonly considered as an African symbol [11-12]. Baobab seeds are rich in protein and contains substantial amount of energy [11]. Baobab seed cake (BSC) has a crude protein content of about 17% [13], which is inadequate for it to be used as a sole protein source in mid-lactating dairy cows. The supplementation of animal rations with a protein source is necessary to meet the protein and amino acid requirements of the animal for a better performance. Many studies have evaluated the effect of Baobab seed cake (BSC) on cows and ewes. To our knowledge, there are few published studies on the effects of Baobab seed cake (BSC) in the lactating goat. However, there is limited information about the feeding value of Adansonia digitata seedcake as feed for goats in Sudan. Furthermore, no studies have investigated the effect of the incorporation of Baobab seed cake (BSC) and ground nut cake mixture in the goats’ diet. In this study aims to evaluate the effects of diets supplemented with Baobab seed cake (BSC) on desert goat milk production performance and quality in North Kordofan state, Sudan.

The experiment was conducted in Al-Newala Village (Longitudes 30.34˚-30.05˚ N, Latitudes 12.93˚-13.34˚E), about 35 km south ELObied town, Sheikan locality in North Kordofan state. Average temperature varies between 30-35oC during most of the year with peaks of above 40oC during April, May and June. The rainy season extends from July to October with maximum rainfall in August. Long-term averages annual rainfall is about 280 mm.

Experimental design and duration 

The study involved three experimental groups and one control group, which made a total of four treatments. A completely randomized design was used for the experiment, with six replicates of pregnant doe's of Desert goats per treatment. animals were randomly distributed to 4 treatments. The experiment lasted for 135 days (7 days pre-experimental period, 45 days for last months of gestation period, and 90 days after kidding).

Experimental animals and feeding management

The study was carried out on Twenty four (24) adult pregnant doe's of Desert goats were used from the last month of pregnancy until 90 day of lactation. The goats were collected from small-scale farmers from in Al Newala Village. The does were of different in age with a range of >1 year to three years of age. The target goats were ear tagged, weighed and randomly divided into four groups A, B, C and D each group component of (6) does according body weight.  All groups were treated against endo-and ecto-parasites, and vaccinated against food and mouth disease, Anthrax and Hemorrhagic Septicemia. All goats were housed in partially shaded pens, constructed from local materials of woods and were equipped with clean water troughs. 

All goats depending on pasture to maintained their roughage and they were daily turned to grazing from 8.00A.m to 6.00p.m. These goats were fed experimental diets containing different levels of baobab seed cake in a formulated diet (Table 1). Group A were used as control with, and managed according to the prevailing traditional system which relies mainly on grazing with no supplementation. Group B, beside allowed to grazing similar to the control group were managed with ration 1. Group C, managed with grazing and supplementing with ration 2, last group D were managed with grazing and supplement with ration 3. Supplementation of groups B, C and D were performed during night after grazing time by rate of 200gm/head/day. Animals were hand milked twice daily.

Milk production

Collection of milk from each lactating doe commenced 7 days after parturition to allow for colostrums intake by the kids. Milking was done by hand twice daily at 7am and 5pm in the presence of the kids for 90 days. Milk let-down was stimulated by the suckling the kid for 5 minutes after which the doe was milked. The milk was weighed using a precision scale (with a sensitivity of 0.1 g). Weight of the kids was taken before and immediately after suckling to estimate milk intake. Kids were separated from does after milking. Milk yield was calculated as the summation of milk off-take and intake by the kid

Milk Composition 

Fresh milk samples were taken every 15 days interval for chemical analysis for 60 days. The Milk samples (20 ml) from each does in all group were collected in sterile containers and kept in a refrigerator adjusted at 5 C0 pending the analysis for chemical composition. The analysis has been done according to methods of [14]; the crude protein was determined by the Kjeldahl method as described by [14]. Crude fiber determination was carried out using trichloroacetic acid (TCA) method. Fat content of milk was analyzed by Gerber method as described by [15]. Ash was determined according to [14]. Lactose and solids, not fat contents, were determined by difference. Analysis was done in the laboratory of Animal Production of ELObied agricultural Research Station, North Kordofan state, Sudan.

Chemical composition of supplementation rations and feeds 

Proximate composition of the ingredients used in concentrated ration formulation, supplemented diets (ration 1, 2 and 3) and some grasses in wet and dry season samples were analyzed following standard procedures, according to Association of the Official Analytical Chemists, [16] (Table.1 and 2).

Table 1: Ingredients of the experimental feed stuffs.

Table 2: Chemical analysis of some grasses in dry season in the study area.

The experimental design adopted for this study was the completely randomized design. All data collected were subjected to analysis of variance procedure using the General Linear Model (GLM) applicable to the experimental design and significant means were separated by Duncan’s multiple range tests, following the procedures of SPSS [17].

Effect of supplementation of baobab seed cake on milk yield

The weekly milk yield of the goats for the 12 weeks of lactation is in (Table 3). Supplementation of baobab seed cake had significantly (P less than 0.05) more milk (116.92 Lb) (51.96 Kg) than those in group C and D as 114.15(50.73Kg) and107.07 Lb (47.59Kg) respectively. The least milk production was produced by group A of 79.73 Lb (35.44 Kg) and which was significantly (P less than 0.05) less than that produced by supplemented groups with baobab seed cake. 

Also, daily milk production was highly significant (P less than 0.05) affected by baobab seed cake where group B which with 65 percentage baobab seed cake had better milk production with 1.30 Lb (35.44 Kg). The daily milk production indicated that the does supplemented with baobab seed cake yielding significantly (P less than 0.01) higher milk than control groups.

The weekly milk yield of the desert goats for the 12 weeks of lactation is shown in (Figure 1). Milk yield increased steadily from the first week of lactation to the sixth week, then dropped for C, D and A groups, whereas sharp declined was noticed in group A. The supplemented groups showed better milk curve with long persistency yielding. The peak for the weekly milk yield was recorded at the 6th week of lactation for all the treatments except for the control (A).

Table 3: Effect of supplementation on milk production/Lb.

Figure 1: Effect of baobab seed cake on lactation curve of desert goats.

Effect of supplementation with baobab seed cake on milk composition

The effect of supplementation on milk chemical composition of experimental desert goats is illustrated in (Table 4). The data indicated that supplementation had exerted a significant (P less than 0.05) effect on fat and protein percentage during 60-90 days. Higher fat percentage during all period of 90 days was noticed in group C in 30-60 days as 3.75% and group D as 3.57%. Protein% showed significant (P less than 0.05) effect during 0-30 and 60-90 days, where high percentages were in group C with 3.77%.  Lactose and as content secured non-significant affected by baobab seed cake supplementation. Beside this, supplemented groups showed higher lactose and lower ash content compared with control group.

Table 4: Effect of supplementation on milk composition%.

Milk production and composition are more depending on composition of the diet fed to animal, the energy balance and energy reserved of the animal. The average total milk production for Desert goats in this study was 104.69±3.36 Lb (46.53 Kg), with daily milk of 1.16±0.04 Lb (0.52 Kg) in a lactation period of 90 days, this level of production was comparable with that reported by [18]for Taggar goats, and lower than that reported by [1-4-8] and higher than that reported by [5]for West African Dwarf Goats Offered Moringa oleifera Herbage Supplement.

The present study indicated that there were highly significant differences in milk yield and daily milk yield between goats of different nutritional supplements with Baobab seed cake during early lactation. Milk yield was highest when baobab was fed at 65 % inclusion in the diet and least when no baobab (control) was fed. Although milk yield of goats fed baobab at 55% or 45 % inclusion was significantly different from each other, it was higher than that of control animals. Milk yield of goats in this study increased with addition of baobab to the diet and was directly proportional to protein intake by the supplemented animals compared to control group. This online with findings of [3-8-19]. Also [5] showed that nutrition improvement with multipurpose trees could be a means of increasing milk yield. Okunlola and Olorunnisomo [3] that the milk yield was significantly affected (P less than 0.05) with supplementation of Baobab seed cake. The supplementation that offered during third period of gestation had positive effect on sustain milk production since around 70% of fetal growth and most of glandular development and mammary tissue occur in this period. For this reason, a strategic supplement of high protein and energy quality should be offered, this fact agreed with [20-21] who reported that good nutrition is a prerequisite high milk yield and a successful rearing system. On the other hand, undernourishment in gestation and lactation in goats can have negative effects on milk yield [22]. Luana et al. [23] concluded that the diet nutritive value and nutritional planes during gestation affect tissue mobilization for support of milk production in early lactation. Generally, the nutritional plane and dietary composition during breeding and gestation (3 to 4 week before parturition) may affect milk yield and reproductive performances which on lines with [24]. Because it may also influence the ruminal microbiome and ruminal fermentation, which subsequently could impact milk production when switched to lactation diets. It was hypothesized that different nutritional planes during gestation may influence Lactational performance and energy utilization in lactating goats fed different lactation diets.

Contrary to the current results [25] found inclusion of Baobab seed cake in the diets of lactating cows reduces milk yield. Also, this result disagrees with the earlier reports of similar work on goats, [23-26] they found that the result from different supplementation showed no significant effect (P> 0.05) of milk production. The dietary concentrate level and nature of specific concentrate and forage feedstuffs impact level of milk production and characteristics of milk [23]. Does on framer's practice (control group) had lower milk yield compared with fed groups, this may be due to less nutrient requirements to meet mammary growth and milk production. Does on control flock began to mobilize their reserve more than does on fed group with baobo seed cake. This significant positive response in milk production observed in does supplemented due to sufficient energy intake by those females that allow for improved production, this agrees with the findings of [27] who reported that supplementing goat ration will increase milk production. This reinforces the argument for the good adaptive response of Desert local goats to erratic feeding conditions. Evidence has been found that under grazing conditions in difficult areas goats adjust their diet selection according to their nutritional needs, especially when the cost of gestation increases the demand for nutrients. The different in milk yield could be due the composition of the diet, type of livestock, and study area was responsible for the variations with the finding in this study, or may be attributed to feed intake and varying inclusion levels of baobab seed cake in the experimental diets.

The lactation curve characteristics of Desert goats showed that the milk production increased for all treatments during early lactation and reached its peak at the 6th week of lactation to reach mid lactation and then subsequently decreased until the 90th day of lactation. Daily milk yield showed significant decrease with advancing lactation, whereas, persistency of milk yield continued three weeks. This appears to be a genetic trait and may not be easily influenced by nutrition as reported by [28], where peak yield tended towards early lactation for local goats. The trend of lactation curve of Desert does in this study is similar to the report of [1-5], this was within the 2 to 5 weeks peak yield reported for Red Sokoto goats by [29] and comparable to 30 days reported for Saanen goats by Souza et al. [30], and not agreed with [4-28] who reported peak yield of milk occurred around 4th week of lactation during the 12-week. The increase in milk production is in line with the combination of several protein feed ingredients in the ration of donations from baobab seed cake and groundnut cake to maintain cells in the mammary gland and the production of hormones and enzymes that play a role in milk biosynthesis. The inclusion levels did not markedly affect yield in the Desert goats used because protein or energy supplements are usually more effective in enhancing milk yield in high genetic dairy goats such as Damascus than they do in low genetic non-dairy or non-selected breeds such as Desert goat. The Desert goat used in this study has not been selected and developed for dairy production.

In this study the values observed for milk components are within the normal range for the goat species, so the composition of the milk (fat and protein) was largely affected by the dry matter intake of the animals of baobab seed cake in the diet, this attributed to the impact of baobab seed cake on ruminal fermentation through enhancing small chain fatty acids and microbial nitrogen production. Similar results recorded by [3-4-8-19-26-31] that the quality of milk produced from these goats fluctuates according to the type of feed given. Also, Póti et al. [32] reported that different feeding strategies have different impact on the chemical composition of goat milk. Contrary to these results [20-33] stated that the composition of milk was not affected by the distributed diet. The absence of diet effects on milk chemical composition could be due to the lack of effects of long-chain unsaturated fatty acids of diets on ruminal bacterial activity [33]. The alternative feed resources are known for their high content in fiber and secondary compounds as phenols and tannins that could affect milk yield and quality by influencing chemical composition and fatty acid precursors in rumen and blood, which agreed with [33].

Fat content varied from 3.28 to 3.60 %, and significantly (P less than 0.05) milk fat yield, and he concluded these improvements followed Moringa oleifera inclusion might due to the high digestibility of dry matter intake, crude protein and crude fiber. Arief et al. [8] reported that enzymes help in the process of milk fat synthesis, where enzymes are proteins. An increased protecting protein supplement increases the number of enzymes to improve the process of milk fat synthesis. In the present study, however, milk fat content is lower at early lactation than at later stages probably because of declining milk yield which made the fat content more concentrated. This type of trend is characteristic of low yielding goats or non-dairy goats [34] or non-selected breeds of animals whose peak yield is usually the initial yield at the beginning of lactation which agreed with [23], where milk fat content decreased with advancing lactation. During early lactation, milk fat content is high not only because nutrients are partitioned towards mammary gland for milk production, but also because transfer of triacyglycerols to milk is more efficient at the beginning of lactation than at later stages. The significant of fat content in this study were not in line with many authors [20-23-35] they stated that milk fat content did not differ between supplemented groups.

The protein content in this study varied from 3.44 to 3.60 %. The protein and fat content of the milk increased with higher levels of baobab seed cake in the diet. This was influenced by the higher protein intake of goats as the level of baobab fruit increased in the diet, the range of protein reported her with in line with [3-4-19-36]. The milk protein content is a trait that changes during lactation and tends to behave inversely to milk yield, reaching minimum values in the second month of lactation, which coincides with the period of maximum milk production. The protein value across treatment contradicts report of [8-23] the result showed that the supplementation treatments did not significantly affect milk protein (P>0.05). Also [34-37] who reported that goats milk protein content was not markedly changed in responses to dietary energy (as fat) supplementation.

Milk lactose almost followed the trend of protein. The Lactose content in this study varied from 4.44 to 4.33 % and there were no significant differences in lactose content of the milk in goats fed different levels of baobab in the diet which on harmony with [3-8] who reported that it has been noted that lactose concentration in milk is not easily altered by nutrition. These results were not in line with the work of [19-35-37] who observed that addition of energy (as sunflower seeds) to goat's ration showed significantly higher lactose content through suckling and lactation. The levels of lactose in supplemented groups are the same as control, this is caused by the protein content of feed in the treatments are still able to meet the needs of the goat and the same as the control treatment. Feed protein will be remodeled into amino acids that are absorbed in the intestine to be converted into glucose in the liver through the process of gluconeogenesis, thereby increasing glucose levels in the blood and then increasing milk lactose levels. Ash content also varied from 0.77 -0.78%. Also, ash wan not affected by feeding baobab seed cake. These results were confirmed by [4-37] that ash values were not influenced (P>0.05) by graded level of baobab pulp and seed in the experimental diets. Disagreed with this El Otmani et al. [333] found that supplementation had significant effect on ash content. Baobab seed cake can be affordable to smallholder farmers who have access to it. Thus, baobab seed cake is a promising non-conventional protein source that has the potential to limit costs of livestock production to all farmers in the tropical region where it is found. However, there is need for sustainable harvesting of baobab to avoid negatively impacting on the environment or upsetting ecosystems especially wild animals which feed on the fruits.

Addition of baobab seed cake to the diet of desert goats increased milk yield of the lactating goats. Protein and fat content of goat milk increased while ash and lactose content were not altered with addition of baobab seed cake to the diet. Baobab seed cake enhanced milk production in desert goats.