| Livestock Research for Rural Development 33 (1) 2021 | LRRD Search | LRRD Misssion | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
Range forages consumed by free-range goats are commonly deficient in protein, energy and minerals resulting in low productivity of the goats. The main objective of this study was to evaluate the effect of whole pumpkin seed meal supplementing diet on growth performance and semen quality of free-range goats. Thirty Malawian local bucks with an initial weight of 12.4±0.3 kg and age of 6 months were studied in completely randomised design. The treatments were: free-grazing with either supplementing diet of pumpkin seed meal or soybean meal and grazing only. The supplementing diets were mixed with maize bran to make them comparable. The supplementing diets were offered to goats (500 g each goat) before grazing (7:00 am) in individual pens followed by free graze for 7h. The experiment ran for 150 days. The measurements included: feed and refusals of the supplementing diet, live body weight, scrotal circumference and semen quality characteristics. The intake of supplementing diets was high in bucks consuming soybean supplementing diet than pumpkin seed meal supplementing diet (P = 0.0489). Bucks supplemented with either soybean or pumpkin seed meal had higher final weight and average daily gain (P < 0.05) than the non-supplemented goats. However, the final live body weight and average daily gain did not differ (P = 0.639) between goats on soybean and pumpkin seed meal supplementing diets. The bucks supplemented with pumpkin seed meal had the widest scrotal circumference (P < 0.05) of all the treatments studied. The bucks fed a supplementing diet containing pumpkin seed meal had higher semen pH (P < 0.05) than bucks on sole grazing group and soybean supplementing diet. Bucks on pumpkin seed supplementing diet had the greatest scores (P < 0.05) on total sperm motility and progressive motility; and sperm concentration followed by the bucks on soybean and the bucks on grazing only had the lowest score. The whole pumpkin seed meal could be used to improve productive performance and semen quality characteristics of free-ranging bucks.
Keywords: average daily gain, bucks, supplements
Goat production is an important livestock activity among smallholder farmers in Africa (Onzima et al 2018). Goats are reared in extensive free-range or herded communally where they graze and browse shrubs on rangeland lands (Brand et al 2018). Range forages consumed by free-range goats are commonly deficient in protein, energy and minerals (Kawas et al 2010) and associated with low growth rates of less than 35g/day (Dereje et al 2015). Exposure to prolonged poor nutrition may result in long-term reduction in fertility including low sperm quality in bucks resulting in low conception in does.
The semen quality of bucks is supposed to be evaluated before selecting them for breeding. However, it is impractical under the smallholder farming conditions to carry out the semen evaluation because of inadequate veterinary services and affordability of the services where they are available.
Improving the nutritional plane of the bucks could be important in improving fertility of breeding bucks. Supplementation of free-range goats with protein, energy, mineral could potentially improve semen quality (sperm motility, concentration, viability and development of accessory seminal fluids). More importantly, trace minerals are vital for improving fertility in ruminants (Hidiroglou 1979).
Pumpkin seeds are valuable source of high-quality protein, fat, zinc, magnesium, phosphorus, copper, potassium, niacin, folic acid, riboflavin, thiamine (Achilonu et al 2018, Nawirska-Olszańska et al 2013 and Eleiwa et al 2014). Therefore, pumpkins seeds could be used as a supplementing diet to improve growth and fertility in free-range or communally herded goats.
In Malawi like the rest of the world, pumpkins are eaten as an energy food and most of the time as part of breakfast, lunch or supper. Normally, farmers select tasty pumpkins and leave out the tasteless pumpkins in the field unharvested and usually get wasted. The tasteless pumpkins could be harvested and prepare their seeds for feeding goats.
The potential of pumpkin seed-based diets in improving poultry production is known. Nonetheless, little is known about their effects on ruminant production including goat production. Therefore, the aim of this study was to evaluate the effect of using whole pumpkin seeds as a supplementing diet for the free-ranging goats on growth performance and semen quality.
The experimental protocol was approved by the Ethics Committee on Use and Care of Experimental Animals of Lilongwe University of Agriculture and Natural Resources, Malawi. The study was conducted at Sankhula Goat Research Farm, Bunda College of Agriculture, Lilongwe University of Agriculture and Natural Resources, Lilongwe, Malawi. The study was carried out between September 2018 and February 2019.
Thirty bucks aged 6 months and weighing about 12.4±0.3 kg were housed in individual covered slatted pens installed with feed troughs and water troughs. The goats were randomly dispensed to three treatments (10 bucks per treatment) in a completely randomised design. The treatments were: grazing with either no supplementation or pumpkin seed meal or soybean meal supplementation. Being animals raised on a free-range, the housing was used for night shelter and to facilitate supplementation and achieve the experimental replication of 10 times.
The pumpkin seed meal and soybean meal supplement diets were mixed with maize bran to achieve 180 g/kg CP DM (Table 1) so that they could be comparable. The supplementing diets were offered to animals between 07:00-09:00hrs before releasing them for free-range foraging. The amounts of supplementing diets offered to the goats were adjusted until the orts were observed in the feed troughs. The animals were allowed to graze for 7 h on a naturally growing grass stand. The goats were allowed to acclimatise to the facilities and supplementing for 14 days followed by the experimental period of 150 days. The samples of the supplementing diets and grasses were sampled monthly and pooled for chemical analysis.
The dry matter, DM (Method 934.01), crude protein, CP (Method 968.06) and ash (Method 920.39) contents were analysed as described by the Chemists 1995. Crude fat was determined using ANKOM fat extractor (ANKOM technology, Model XT10l, Macedon, NY, USA). Neutral detergent fibre (aNDFOM) was analysed using heat-stable alpha-amylase and sodium sulphite and exclusive of ash (Mertens et al 2002). Minerals (major and trace) were analysed using Microwave Plasma Atomic Emission Spectrophotometer (Agilent Technologies, Model MY16490002, Australia).
Live body weight was measured every 14 days using a crate fitted with analogue Salter Weighing Scale. The testicular development was determined through measurements of the scrotal circumference for every two weeks. The measurements were done using a scrotal measuring tape and was taken at the widest point of the testicles. The testes were allowed to settle or gently hand-squeezed into the scrotum before taking the measurement. The final weight of the testicles was measured as the weight of the pair of the testicles after slaughter.
The collection of semen was done in last three weeks of 150-day long experiment. The semen was collected once a week for three weeks. The semen ejaculation was achieved by a Ram Lane Electro-Ejaculator (Lane Manufacturing Inc, USA). The semen was collected following the procedure described by (Lukusa and Lehloenya 2017). After collection, the tubes containing the semen were immediately placed in thermoflasks with water set at 30 0C and the microscopic evaluation was done within one hour after collection.
The semen quality evaluations were done by modifying the methods reported by (Lukusa and Lehloenya 2017). The volume of the ejaculate was measured immediately after ejaculation in graduated semen collection tubes. The pH was determined by placing a single drop of the semen on a litmus paper for 3 minutes and compare the resultant colour against the pH Colour Chart (NAGEL, Duran, Germany). To measure the sperm motility a drop of physiological saline (diluter) was placed on a pre-warmed glass slide and on it the drop of semen was put using a solid clean glass rod (semen-straw sized) and mixed. A drop of the mixture was then transferred to the clean part of the slide, place a cover slide and observe under 40 × magnification using the compound microscope (Olympus, CX23, Tokyo, Japan). Total motility and progressive motility of spermatozoa were scored by the manual counting method using a Hand Tally (ENM, Rd.97218, England).
The sperm concentration was determined by means of a Neumblar haemocytometer (Hausser, Horsham, PA USA). The semen samples were diluted in the ratio of 1:1000 by sodium citrate. After thoroughly mixing, semen was filled on both sides of hemocytometer and read the sperm heads in the large center square. The number of sperms were multiplied by 10,000 to obtain the number of sperms per ml of the diluted sample and then by the dilution factor (1,000) to get the actual sperm count. To obtain the sperm concentration per ml and per ejaculate the following equation used:
Sperm concentration/ml = Sperm count x 1000000
To calculate sperm concentration per ejaculate, the following equation was used:
Sperm concentration/ml ejaculate = Sperm concentration/ml x semen volume
All data were analyzed in SAS Version 9.2 (SAS Institute, Cary Inc, NC). The data for dry matter intake and growth performance were analyzed using general linear model to determine effects of supplementation. The initial body weight was fitted as a covariate. The data for scrotal circumference and semen quality characteristics were analyzed as the repeated measures with week of measurement as the repeated measure and subject as a goat within the treatment. The significant variation was confirmed at P < 0.05. Where the variation was confirmed, the means were separated by the PDIFF option of the SAS.
The profile of chemical composition of the supplementing diets are summarized in Table 1. Overall, the supplementing diet containing pumpkin seed had better profile of mineral composition than the supplementing diet containing the soybean meal.
In terms of intake of the supplementing diet and growth performance (Table 2), bucks consuming soybean supplementing diet had higher intake than pumpkin seed meal supplementing diet (P = 0.0489). Both final body weight and average daily gain was influenced by the supplementation ( P <. 000112). Goats supplemented with either soybean or pumpkin seed meal had the higher final weight and average daily gain (P < 0.05) than the non-supplemented goats (Table 2). However, the final live body weight and average daily gain did not differ (P = 0.639) between goats supplemented with soybean and pumpkin seed meal (Table 2).
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Table 1. Chemical composition of the supplementing diets (g/kg) |
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|
Pumpkin seed supplementing diet1 |
Soybean |
Forages in |
|
|
Dry matter, g/kg |
901 |
907 |
890 |
|
Crude protein, g/kg DM |
179 |
190 |
141 |
|
Ash, g/kg DM |
103 |
98.0 |
81.0 |
|
Crude fat, g/kg DM |
189 |
117 |
2.10 |
|
aNDFOM3, g/kg DM |
266 |
272 |
736 |
|
P, g/kg DM |
5.00 |
3.00 |
1.00 |
|
Ca, g/kg DM |
0.410 |
0.340 |
3.26 |
|
Mg, g/kg DM |
0.332 |
0.241 |
0.431 |
|
Fe, mg/kg DM |
2112 |
1146 |
0.00 |
|
Mn, mg/kg DM |
272 |
92.0 |
5.68 |
|
Zn, mg/kg DM |
59.0 |
28.0 |
16.7 |
|
Cu, mg/kg DM |
40.1 |
12.2 |
0.00 |
|
1Pumpkin seed meal+maize bran+ common salt;2
Soybean meal+ maize bran+ common salt; |
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Table 2. Intake and growth performance of free-range goats supplemented with pumpkin seed meal as protein source alternative to soybean meal |
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|
No |
Pumpkin |
Soybean |
SEM |
P-value |
|
|
Dry matter intake, g |
- |
407b |
417a |
5.58 |
0.0489 |
|
Final body weight, kg |
17.5b |
22.3a |
21.8a |
0.94 |
<.000112 |
|
Average daily gain, g |
44.0b |
83.1a |
79.8a |
0.30 |
0.0462 |
|
Means in the same row with different superscripts are significantly different at p = 0.05 significance level; 1Pumpkin seed meal+maize bran+ common salt ;2Soybean meal+ maize bran+ common salt |
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The time of measurement had an effect on the scrotal circumference (P <.0001) whereas supplementation did not have the effect (P = 0.492). However, there was a significant interactive effect ( P <. 0001) between the time of measurement and supplementation on scrotal circumference. The profound differences in scrotal circumference in the bucks occurred from the week 12 of the experimentation (Figure 1).
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| Figure 1. Changes in scrotal circumference over time in free-range goats fed with different supplementing diets |
The goats supplemented with pumpkin seed meal had consistently the widest scrotal circumference (P < 0.05) followed by the goats supplemented with the soybean meal whereas the non-supplemented goats had the narrowest scrotal circumference from week 12 (Figure 1).
The final weight of pair of the testes of the goats varied with supplementation (P = 0.0001). The goats fed with supplemented with the pumpkin seed meal as a protein supplement had the greatest final testicular weight (328 ±11 g) followed by the goats supplemented with the soybean meal (290 ±12g) whereas the non-supplemented goats had the smallest testis weight (243 ±12g).
Neither time (week) of measurement nor the interaction of time and supplementation influenced (P > 0.05) the semen quality attributes evaluated. Nevertheless, supplementation had an influence ( P = 0.0025) on all semen quality attributed evaluated (Table 3). The semen volume per ejaculate was highest in goats fed the supplementing diet containing soybean meal followed by goats with no supplementation and the goats fed pumpkin based supplementing diet had the smallest semen volume.
The bucks fed a supplementing diet containing pumpkin seed meal had higher semen pH (P < 0.05) than bucks on sole grazing group and soybean supplementing diet. Bucks on pumpkin seed supplementing diet had the greatest score (P < 0.05) on total sperm motility and progressive motility followed by the bucks on soybean and the bucks on grazing only had the lowest score. The semen concentration per ml and per ejaculate were both highest in goats on pumpkin seed supplementing diet followed by those on soybean diet and the goats sole grazing had least concentration.
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Table 3. Semen quality attributes of free-range goats fed supplementing diets containing either pumpkin seed meal or soybean meal |
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|
No |
Pumpkin |
Soybean |
SEM |
P-value |
|
|
Volume (ml/ ejaculate) |
0.84b |
0.71c |
1.00a |
0.071 |
0.003 |
|
pH |
6.61b |
7.19a |
6.75b |
0.16 |
0.004 |
|
Total motility (%) |
62.8c |
76.6a |
66.2b |
2.31 |
<.0001 |
|
Progressive motility (%) |
26.3c |
48.9a |
32.6b |
2.76 |
<.0001 |
|
Concentration (×109 cells /ml) |
0.83c |
1.87a |
1.38b |
0.099 |
<.0001 |
|
Concentration (×109 cells /ejaculate) |
0.71b |
1.24a |
1.27a |
0.13 |
0.0007 |
|
Means in the same row with different superscripts are significantly different at p = 0.05 significance level; 1Pumpkin seed meal+maize bran+ common salt; 2 Soybean meal+ maize bran+ common salt. |
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The results of higher dry matter intake of the soybean supplementing diet than whole pumpkin seed supplementing diet by the goats could be associated with the high fat content in the pumpkin supplementing diet. Inclusion of oil-rich feed supplements in a diet decreases dry matter intake in goats (Hess et al 2008). However, lack of differences in final weights and average daily gain between bucks fed with pumpkin seed meal and soybean supplementing diets might be because of similar nutrient profile of the diets. Similar findings were reported by (Antunovic et al 2018) who found that the partial replacement of soybean meal with pumpkin seed meal did not alter production performance of lambs. The animal productivity benefits from pumpkin seed meal are ascribed to its high concentration of protein, fat and mineral content and antioxidant capacity (Achilonu et al 2018, Valdez-Arjona and Ramírez-Mella 2019).
The superior scrotal circumference and testicular development (weight) in bucks on the pumpkin supplementing diet could be associated with better mineral composition particular the composition of trace elements (Fe, Mn, Zn and Cu) in the diet than the soybean supplementing diet. Adequate intake of manganese, zinc and copper increases reproduction performance in ruminants through enhancement of enzyme activation and antioxidant activity (Ghorbani et al 2018).
The values of semen pH obtained in this study were within the range of the normal pH of semen bucks (Patel 1967). The more alkaline sperm conditions of semen of the bucks on the pumpkin seed supplementing diet than other diets could be because of better mineral content that might have resulted in better testicular development. The better testicular development in goats supplemented with the pumpkin supplementing diet was shown by the wider scrotal circumference and testicular weight. The semen composition is dominated by seminal vesicular secretions followed by prostatic secretions (Owen and Katz 2005). The pH of seminal vesicular secretion is alkaline while prostatic secretions are acidic (Raboch and Skochova 1965), therefore better testicular development in pumpkin seed fed goats might have modified the biochemical reactions to favour the alkaline semen conditions (Ortiz-de-Montellano et al 2007).
The results of the smallest semen volume in bucks supplemented with pumpkin seed meal of all the treatments could not be easily explained as it is well established that high levels of dietary trace minerals improve semen production capacity including semen volume (Arangasamy et al 2018). The high score of sperm motility and concentration for bucks on the pumpkin supplementing diet might be associated with higher concentration of trace minerals in the pumpkin supplementing diet than soybean and sole grazing. Trace minerals play a vital role in controlling spermatogenesis where they act as cofactors for both DNA and RNA polymerase activities (Arangasamy et al 2018). The trace minerals (Fe, Mn, Zn, Cu and Se are mediators of the effects of oxidative damage and play an essential role in spermatogenesis (Rahman et al 2014). In the current study, pumpkin supplementing diet had a high Zinc concentration which was above the Zinc requirements for ruminants of 40 mg Zn/kg feed which may explain why the bucks on pumpkin seed meal had better semen production capacity.
This work was supported by the USAID under the Africa Rising/Transforming Key Production Systems project in Malawi.
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