Abstract: Objective: This study was conducted to investigate the effect of feeding a high proportion concentrate containing tofu waste on nutrient consumption, milk production, body condition (BC) score and length of postpartum mating (PPM) period of dairy goats. Methodology: Data were collected from 30 lactating goats on small farms in the Sleman region of the Yogyakarta province in Indonesia. The goats were fed diets consisting of Calliandra calothyrsus and wheat pollard with (Farm B, Diet B) or without (Farm A, Diet A) tofu waste. The proportion of concentrates in the diets on a dry matter (DM) basis was 20 and 55% for Diet A and Diet B, respectively. Data for feed and nutrient consumption, milk production, BC score and length of PPM period were collected. All data were statistically analyzed by t-test. Results: Feeding a high proportion concentrate containing tofu waste significantly (p<0.05) decreased DM and crude protein (CP) intake but did not affect the consumption of crude fiber and total digestible nutrients. High proportion concentrate significantly (p<0.05) lengthened PPM period but no effect on milk production. Long PPM period presumably associated with the presence of tofu waste in high concentrate diet. Conclusion: Diets containing high proportion concentrate with tofu waste did not affect milk production or BC score but lengthened the PPM period. Thus, the proportion of tofu waste can be reduced to avoid negative effects of phytoestrogens contained in the tofu waste on reproductive performance.
INTRODUCTION
The contribution of dairy goats to meet the demand for milk in Indonesia has recently increased. In particular, small farms producing goat milk play a significant role in milk production on Java Island. One constraint dairy goat farmers face is limited forage, which can be affected by several factors, including farm size and labor availability. In response to such limitations, farmers often seek alternative feeds to substitute for forage. On small farms, leguminous leaves are mainly used for goat feed. In the Yogyakarta province, goat farmers typically use Calliandra calothyrsus due to its rapid growth and palatability1, which exceeds that of other forages such as Leucaena and Albizia2. Calliandra calothyrsus grows in many soil types, including acidic soils (pH 4.5)3 and this plant is adapted to a wide range of habitats, including those having various elevations (from sea level to 1850 m above sea level) and annual rainfall (between 700-4,000 mm year–1)4. The optimal cutting time for Calliandra is 6 months before the middle of the dry season5 and plants cut at 16 week of age produce the highest quantity of fresh forage, dry matter (DM), organic matter and crude protein (CP)6. A high proportion of forage in dairy goat feed increases milk production, milk fat and decreases ruminal acidity7. However, as with other forages, the availability of Calliandra decreases during the dry season8. Thus, alternative, supplementary feed is needed to sustain milk production throughout the year.
Several food by-products are available in rural areas, including tofu waste, which farmers commonly purchase from tofu processing plants. Tofu waste has economic benefit due to its low price and continuous availability. With an average protein and fiber content of 23.39 and 19.44%, respectively, tofu waste is a good source of protein and fiber9 and thus is used as a concentrate in feed for pigs10 and dairy cows11, Muscovy ducks12 and steers13.
Although, there is currently limited information about the use of tofu waste in feed for dairy goats and particularly its safety and effect on milk production, tofu waste is commonly used as a supplement for fattening goats14. Tofu waste also serves as a substitute for grass in goat production in Banjarnegara, Central Java during the dry season15. Another study conducted in the village of Sukorejo, Turi, Indonesia, examined the effects of a combination of tofu and Calliandra in goat feed, although how the diet impacted goat productivity was not assessed16. According to Wina et al.9 the high solubility and digestibility of protein in tofu waste is beneficial but in vitro assays showed decreases in tofu waste protein digestibility with increasing amounts of Calliandra calothyrsus in feed.
To attain optimal milk production from goats, assessment of the utilization of high proportion concentrates in goat feed from the perspective of nutritional adequacy and milk production is needed, particularly for small farms. The nutritive status of goats can be determined by evaluating body condition (BC) score17. Low body energy reserves associated with low BC score can reduce milk yield18 and negatively impact reproduction by reducing levels of plasma follicle stimulating hormone (FSH)19.
In this study we assessed the effect of feeding a high proportion concentrate containing tofu waste on nutrient consumption, milk production, BC score and the length of the postpartum mating (PPM) period of goats. Results from this study will provide useful information about food by-products as sources of protein and fiber to provide adequate nutrition and maintain milk production by dairy goats, as well as demonstrate the usefulness of tofu waste as a substitute for forage.
MATERIALS AND METHODS
This study involved small dairy goat farms in the Sleman region of Yogyakarta province in Indonesia, which is located on the latitude between 110°33’ 00” and 110°13’ 00” and 7°34’ 51” and 7°47’ 30” east and south, respectively, at 1,000 m above sea level20 (Fig. 1).
Data were collected from 30 lactating Etawah Crossbred goats (Fig. 2) on Farms A and B. The goats were fed two types of diet consisting of leguminous tree leaves (Calliandra calothyrsus) and wheat pollard that lacked (Farm A, Diet A) or included (Farm B, Diet B) tofu waste substituted for 35% of forage DM (Table 1). Diets A and B had 20 and 55% concentrates, respectively, on a dry matter (DM) basis. Farm A represented common feeding of dairy goats in smallholder farm in Sleman, whereas Farm B was an example of feeding high proportion concentrate.
Goats were in the mid-lactation phase (3-4 months after kidding) of their second or third lactation period. The initial body weight of the goats was between 44.0-50.0 kg. Milk production in previous lactation phase(s) was approximately 1.0-2.0 L d–1 and the litter size was 1-2 kids/doe. All goats were managed in a confined system in individual pens that had feed troughs and water containers. Calliandra calothyrsus (Fig. 3a) was harvested from the farmers’ land. Tofu waste (Fig. 3b) was purchased from local processing plants near the farms. Chemical analysis of samples was conducted at the Laboratory of Animal Nutrition and Laboratory of Dairy Science and Milk Industry, Faculty of Animal Science, Universitas Gadjah Mada, Yogyakarta, Indonesia.
| Fig. 1: | Map of the Sleman region in the Yogyakarta province of Indonesia |
| Fig. 2: | Etawah crossbred goat |
| Table 1: | Diet compositions |
Data for feed and nutrient consumption were collected for 14 consecutive days from the beginning of the study. Feed intake was determined as the difference between weights of offered and refused feed after 24 h. Tofu waste was mixed with wheat pollard and given prior to feeding forage. Chemical composition of feed expressed as DM, crude protein (CP), fat, crude fiber and total digestible nutrients (TDN) was determined according to AOAC guidelines21. Nutrient intake was calculated by multiplying the weight of feed consumed by nutrient content. Milk production was measured across 30 days in the middle of the study period.
| Fig. 3(a-b): | (a) Calliandra calothyrsus (b) Tofu waste |
Body condition (BC) score was measured at the beginning and end of the experimental period. Body condition scoring was performed by palpating muscle and fat deposits over and around the vertebrae and in the loin region of the goat. BC score ranged from 1-5 points22 and represented the average results for examinations by three evaluators. BC scores were: 1: Very thin, highly visible back bone having no visible fat cover, 2: Thin (bony), visible backbone having a continuous ridge, 3: Good, in which the backbone was not prominent and a thick tissue layer covered the vertebrae, 4: Back bone and ribs could not be seen and 5: Presence of excessive fat and a back bone buried in fat18,23. Reproductive performance was determined by assessing the length of the postpartum mating (PPM) period, based on the reproduction records available at the farm and interviews. PPM data were obtained used questionnaires pertaining to kidding time, first estrus after kidding and service/conception. All data were statistically analyzed by t-test at 5% level of significance.
RESULTS
The chemical composition of Diets A and B fed on Farms A and B, respectively, showed a lower DM and crude protein (CP) for Diet B (high proportion concentrate) compared to that of Diet A (low proportion concentrate) (Table 2). Meanwhile, Diet B was higher in crude fiber, fat and total digestible nutrient (TDN) content than Diet A. The ratio of TDN : Crude protein for Diet B was 2.5:1, whereas that for Diet A was 2.2:1. Thus, the results indicated that inclusion of tofu waste increased the energy content of Diet B and in turn the available energy for rumen fermentation was higher for Diet B than Diet A.
Goats fed Diet A, which has a high proportion concentrate, had significantly (p<0.05) decreased DM and CP intake (Table 3). The average DM intake of the goats on Farm A and Farm B was 117.78±7.85 and 105.83±17.57 g kg–1 BW0.75, equivalent to 4.38 and 3.90 g kg–1 body weight (BW), respectively. No significant differences were seen between the diets for crude fiber, fat and TDN intake. Together these results indicate that high proportion concentrate containing tofu waste (Diet B) provides adequate fiber and energy but is a less useful protein source.
There were no differences between average milk yield of goats on Farms A and B during the mid-lactation stage (the period after peak production) (Table 4). The average milk yield ranged between 1.0-1.2 L d–1, which was consistent with the milk capacity of Etawah Crossbred goats under smallholder conditions. At the beginning of the experimental period the two diets had no effect on BC score and by the end of the period (around 7 months after kidding) the BC score increased for both groups. The average initial BC score values were 2.7 and 2.9, for Farm A and B goats, respectively, which increased to 3.0 and 3.1 by the end of the experimental period (Table 4), indicating that goats on both farms consumed adequate nutrients.
The period between PPM for goats on Farm B was longer than that for Farm A, with an average of 6.2 and 3.4 months, respectively (Table 4), suggesting that feeding high proportion concentrates containing tofu waste decreased the reproductive activity of the goats and that inclusion of tofu waste in feed could be used to lengthen the PPM period.
| Table 2: | Chemical composition of the diets |
| DM: Dry matter, CP: Crude protein, CF: Crude fiber, EE: Ether extract, TDN: Total digestible nutrient | |
| Table 3: | Feed and nutrient consumption of the diets |
| a,bMean values in the same row with different superscripts showed significant differences (p<0.05), nsNon significant (p>0.05) | |
| Table 4: | Milk production, body condition score and postpartum mating period of goats |
a,bmean values in the same row with different superscripts showed significant differences (p<0.05), nsNon significant (p>0.05) |
|
DISCUSSION
In this study, the proportion of concentrate was as high as 55% of total feed DM for Diet B. No significant differences were observed in milk production or BC score for high and low proportion concentrates. This result is consistent with the findings of Rapetti and Bava24 and Goetsch et al.25, who reported that 60-70% DM in concentrates did not alter the productive capacity of goats. However, a significant decrease was observed in DM and CP intake for the high concentrate diet containing tofu waste (Farm B, p<0.05). Decreases in DM intake could be related to the physical properties of tofu waste, which is wet, such that upon consumption the water volume in the rumen would increase and in turn depress subsequent consumption of leguminous leaves to reduce DM intake. According to Shittu et al.26 goats can adapt to a broad range of feeding conditions, whereas Silanicove27 and Carlson28 described diets in which goats were given feed having an intermediate DM level, which lowers the risk of acidosis and tends to move toward concentrate selectors. Thus, use of feed having high proportion concentrates should be acceptable for goats given their high adaptability. The level of DM intake by goats on both farms was similar (4.1-5.3% of BW)29. The value for DM intake (112 g kg–1 BW), was also in the range of that reported in a previous study30. Therefore, both diets provided sufficient DM for lactating goats.
The goat feed used in this study had a CP content ranging from 20.9-22.2% and is thus protein rich. These values are higher than the range (14.0-20.3%) previously cited as being the optimal protein level for goat feed31. Results of the present study indicate that tofu waste and Calliandra calothyrsus were good protein sources for goats. However, digestibility must also be considered. Wina et al.9 reported that feed digestibility decreased from 74-70% upon inclusion of tofu waste with Calliandra calothyrsus. According to a study by Umiyasih and Anggraeny32 although feeding wet concentrate could increase by-pass protein, it negatively affected nutrient absorption due to the high flow rate of passage. Here, the physical form of the high proportion concentrate containing tofu waste in Diet B could protect proteins in the tofu waste from rumen degradation. Therefore, despite the low protein consumption of goats fed Diet B, these animals could in fact absorb more protein from the tofu waste. In addition, we found that tofu waste could serve as a crude fiber source to replace the 35% of DM provided by Calliandra calothyrsus in Diet A.
Milk production by goats in this study was not affected by the proportion of concentrate in the diet. The average milk production (0.7-1.6 L d–1) was in the normal range for Etawah Crossbred goats under smallholder conditions33. These results indicate that tofu waste can be included in high proportion concentrate diets to maintain milk production.
Goats fed tofu waste in the high proportion concentrate diet had good BC score that exceeded previously reported values of 2.0634 and 2.2535. This result is consistent with earlier common use of tofu as a supplement in fattening rations for goats13. Here, the high BC score was likely indicative of available energy reserves and could be associated with a high energy density expressed as TDN content (Table 1). Together the high BC score and milk yield of goats in this study was consistent with the findings of Rapetti and Bava24 and Goetsch et al.25, who showed that diets rich in concentrate could negatively influence milk production during the mid-lactation phase and cause excessive fattening.
The effect of feeding high proportion of concentrate containing tofu waste lengthened the PPM period. According to Jalilian and Moeini19, decreases in reproductive performance were associated with low BC score, which could influence plasma FSH concentrations. Here we saw no association between PPM and BC score, which, at 2-3, was within the range that is ideal for breeding18. Therefore, other factors, such as lactation period and the presence of phytoestrogens in tofu waste, were presumably responsible for the long PPM period of these goats. According to Koyuncu and Altincekic18 and Hussain et al.36 adequate amounts of milk could be produced if animals consume sufficient nutrients and maintain optimal body conditions during the lactation period. Similar results were found in this study by the end of the lactation period the BC score had increased. Lactating goats that are continuously milked likely call on reserve nutrients to maintain milk production. High energy reserves associated with BC score in goats could be directed to milk production rather than to support reproductive activity, which in turn lengthens the PPM period. This possibility is supported by the high blood glucose levels seen in this study (between 26 and 28 mg dL–1) (Table 5), which were higher than normal levels37. These high glucose levels could be needed to supply sufficient glucose for lactose biosynthesis during milk production.
As mentioned above, the PPM in goats fed high proportion concentrate containing tofu waste might be affected by the presence of phytoestrogen-isoflavones in soy beans38.
| Table 5: | Blood metabolite profiles of goats |
a,bMean values in the same row with different superscripts showed significant differences (p<0.05), nsNon significant (p>0.05) |
|
The effects of phytoestrogens vary from an estrogenic over-response, thus increasing secretions in the reproductive tract, to infertility and disruption of animal behavior39. Typically, phytoestrogens exert their estrogenic effect on the central nervous system and the reproductive system to induce estrus and stimulate growth of genital tract and mammary gland tissues in females40. The longer PPM period seen for goats fed tofu waste might be caused by repeated estrus. Thus, the possible negative effect of phytoestrogen-isoflavones on reproductive performance should be considered and weighed against the benefits provided by tofu waste in terms of price and palatability.
CONCLUSION
Feeding high proportion concentrates containing tofu waste in the diet significantly (p<0.05) decreased DM and CP intake of lactating goats but did not affect crude fiber and TDN consumption. Tofu waste could be used as a substitute for leguminous material as a source of protein and crude fiber. Feeding high proportion concentrates containing tofu waste did not affect milk production or BC score but did prolong the PPM period. Thus, the proportion of tofu waste can be reduced to avoid negative effects of phytoestrogens contained in the tofu waste on reproductive performance.
SIGNIFICANCE STATEMENT
This study described tofu waste as an alternate source of protein and fiber for goat feed. Lactating dairy goats fed diets containing tofu waste maintained milk production and good BC score. The proportion of tofu waste in diets can be managed to avoid negative effect of phytoestrogens contained in the waste on reproductive performance of goats and to maintain optimal length of PPM periods. This study provides critical information for strategies to maintain optimal nutritional value of goat feeds in tropical regions that experience decreases in forage availability during the dry season.
ACKNOWLEDGMENT
The authors are grateful to Faculty of Animal Science Universitas Gadjah Mada for funding the study.