Nutritional strategies with dried distillers’ grains with solubles (DDGS): effects on saanen goat milk and lactation dynamicsABSTRACT
This study evaluated Saanen goats' milk yield and quality on diets where dried distillers' grains with solubles (DDGS) partially or fully replaced soybean meal (SBM). Fifteen goats were randomly assigned to three treatments-SBM, SBM+DDGS, and DDGS diets-using a 60:40 forage-to-concentrate ratio, with five replicates each. The experiment covered four phases (1-30, 31-60, 61-90, and 91-120 days in milk). Wood's nonlinear Bayesian model estimated the lactation curve, and Tukey's test assessed milk quality. No significant differences (p > 0.05) were found in body weight, dry matter intake, daily milk yield, or milk quality. However, initial milk yield, peak production rate, and decline rate differed significantly (p < 0.05) among diets. The SBM+DDGS diet proved viable from kidding to 120 days, enhancing milk production and optimizing diet efficiency.
Keywords:
co-product of ethanol production; dairy goats; lactation; production efficiency; somatic cells
RESUMO
Este estudo avaliou a produção e a qualidade do leite de cabras Saanen em dietas em que os grãos secos de destilaria com solúveis (DDGS) substituíram parcial ou totalmente o farelo de soja (SBM). Quinze cabras foram distribuídas aleatoriamente em três tratamentos - dietas SBM, SBM+DDGS e DDGS - utilizando-se uma proporção de 60:40 de volumoso para concentrado, com cinco repetições cada. O experimento abrangeu quatro fases (1-30, 31-60, 61-90 e 91-120 dias de lactação). O modelo bayesiano não linear de Wood estimou a curva de lactação, e o teste de Tukey avaliou a qualidade do leite. Não foram encontradas diferenças significativas (P>0,05) no peso corporal, no consumo de matéria seca, na produção diária de leite ou na qualidade do leite. No entanto, a produção inicial de leite, a taxa de produção no pico e a taxa de declínio diferiram significativamente (P<0,05) entre as dietas. A dieta SBM+DDGS mostrou-se viável, do parto até 120 dias, aumentando a produção de leite e otimizando a eficiência da dieta.
Palavras-chave:
cabras leiteiras; células somáticas; coproduto da produção de etanol; eficiência de produção; lactação
INTRODUCTION
Dairy goat production has surged recently, largely due to high-yield breeds like Saanen, known for superior milk production (Fonseca et al., 2016). Goats have a keen ability to sort feed but are prone to disorders like acidosis, akin to dairy cows (Giger-Reverdin et al., 2020). With growing demand for goat milk, producers have adopted innovative feeding strategies.
Milk yield and quality depend on factors such as diet, breed, lactation stage, and environment. Using agro-industrial by-products in diets is common to boost milk production and cut costs (Stuani et al., 2016). Dried distillers' grains with solubles (DDGS) are valued for their high protein content (>30%) and are used in ruminant diets, fulfilling protein needs without urea (Freitas et al., 2017; Pontes et al., 2020).
Understanding the lactation curve is key for dairy goat management. Wood's model (1967) estimates lactation parameters like peak yield, time to peak, and persistency. These parameters, affected by diet, influence milk production (Zambom et al., 2017).
This study evaluates the lactation curve and milk quality of Saanen goats on diets where DDGS partially replace soybean meal (SBM).
MATERIAL AND METHODS
The experiment took place at the Goat Study Unit of the Experimental Farm of Iguatemi, part of the State University of Maringá, Brazil. Approval was granted by the Ethics Committee on Animal Use of UNIOESTE (protocol No. 29/18). Fifteen lactating Saanen goats, averaging 55kg and aged 1 to 5 years, were randomly assigned to three dietary treatments with five replicates each: SBM, SBM+DDGS, and DDGS, replacing soybean meal with dried distillers’ grains with solubles. The diet had a 60:40 forage-to-concentrate ratio, using corn silage and a concentration of ground corn and minerals (Tab. 1 and 2).
Pontes et al. (2020) previously used these diets to assess their nutritive value. Goats were assigned based on body weight and milk yield, with DDGS provided by an industry in São José do Rio Claro, Mato Grosso, Brazil.
A 10-day adaptation period preceded the experimental phases: 1-30, 31-60, 61-90, and 91-120 days in milk. Goats were grouped by kidding dates into four groups. Samples of feed, refusals, feces, and blood were collected from all goats during each phase. Diets met the nutritional requirements for a 60-kg lactating Saanen goat producing 3.0kg of milk daily (National…, 2007).
Goats were housed in individual pens with slatted floors, equipped with feeders, drinkers, and mineral troughs, and had 30 minutes of outdoor access post-milking. Milking occurred twice daily, at 8:00 a.m. and 4:00 p.m., to record daily milk yield and goats were weighed at kidding and every 15 days thereafter. The goats were weighed immediately after kidding and subsequently every 15 days until 120 days in milk, always following the first milking and before the morning feeding.
Monthly milk samples were collected and analyzed for fat, protein, lactose, and defatted dry extract using ultrasound spectroscopy at CMETL. Somatic cell count (SCC) was determined with the Ekomilk Scan®. Milk urea nitrogen (MUN) was analysed using commercial kits (urea-PP kit, category 427; Gold Analyzes Diagnostica®). Milk production was adjusted to 3.5% fat content with the formula: FCM (3.5%) = 0.4337 * MP + 16.218 * FP, where FCM = fat-corrected milk, MP = milk production (kg/day), and FP = fat production (kg/day).
Linear models evaluated diet impacts on milk yield, composition, and quality, with Tukey's test (p < 0.05) used for model selection in SAS software (Version 9.0). Daily yields were adjusted using nonlinear regression to estimate lactation curve parameters via Wood’s equation (1967), , in which i-animal = 1, 2, 3 … N; j-time = 1, 2, 3, … J; k-treatment = 1, 2, 3, ... K; y = milk yield (kg/day); a = initial milk yield (kg); b = rate of increase to peak production; c = rate of decline after peak (persistency factor); t = days in milk.
Bayesian analysis addressed low replicate numbers and compared lactation curve parameters (Rossi, 2011). Non-informative priors were used for model parameters.
The model for total milk yield was: Yik = μ + ak + eik, assuming a normal distribution for responses. Priori distributions were μk ~ N (0.10-6) and tk ~ Gamma (10-3, 10-3). Multiple comparisons used posterior parameter estimates, considering differences significant at 5% if zero was outside the 95% confidence interval. Marginal posterior distributions were obtained using R software with the BRugs package. For each parameter, 1,100,000 MCMC elements were generated, with the first 100,000 discarded and a thinning interval of 100 applied. Convergence was verified using the Heidelberger and Welch (1983) test from the CODA package in R.
ETHICAL ASPECTS
The research was submitted to the Ethics Committee on Animal Use of the University of UNIOESTE, Marechal Cândido Rondon - PR and approved under the number 29/2018.
RESULTS
There were no significant differences (p > 0.05) in body weight among Saanen goats across the treatments from kidding to 120 days in milk, with average body weights of 49.53, 50.97, 51.33, and 52.80kg for the periods of kidding to 30 days, 31 to 60 days, 61 to 90 days, and 91 to 120 days in milk, respectively (Table 3).
No significant differences (p > 0.05) were observed in dry matter intake across treatments during the periods of kidding to 30 days, 31 to 60 days, 61 to 90 days, and 91 to 120 days in milk, with average intakes of 1.62, 1.63, 1.70, and 1.75 kg/day, respectively. Similarly, treatments had no effect (p > 0.05) on daily milk yield and milk composition from kidding to 120 days in milk (Table 4).
Diets in which dried distillers’ grains with solubles (DDGS) partially or fully replaced soybean meal (SBM) significantly influenced (p < 0.05) lactation curve parameters, including initial milk yield (a), rate of increase to peak production (b), rate of decline after peak (c), peak lactation yield (PLY), lactation persistency (PERS), and peak lactation day (LD) (Table 5). Initial milk yield was highest for goats on SBM diets, averaging 2.60kg, compared to those on SBM+DDGS and DDGS diets, which averaged 2.49 kg and 1.82kg, respectively.
Total milk yield increased for DDGS-fed goats from kidding to 30 days and from 31 to 60 days in milk. However, it decreased from 61 to 120 days in milk, resulting in lower lactation persistency (Table 5). Substituting SBM with DDGS in the diets affected peak lactation day values (Fig. 1), leading to an earlier peak due to reduced milk yield.
Adjusted lactation curves of Saanen goats fed diets containing dried distiller’s grains with soluble in replacement of soybean meal. SBM: soybean meal; SBM+DDGS: soybean meal + dried distiller’s grains with soluble; DDGS: dried distiller’s grains with soluble.
DISCUSSION
Significant differences in total milk yield were observed among treatments (p < 0.05, Tab. 2), with higher yields in goats on SBM and SBM+DDGS diets, suggesting DDGS can be used in Saanen goats' diets from kidding to 120 days without affecting production. Milk fat content remained stable across treatments (p > 0.05) during all lactation phases, likely due to similar protein levels in the diets (Cannas and Pulina, 2008). The average fat content matched Brazilian Normative Instruction No. 37 (2000), which states an average of 3.28%. Milk protein content also showed no significant differences (p > 0.05) across lactation phases, averaging between 3.22% and 3.32%, aligning with previous studies (Gomes et al., 2004; Madureira et al., 2017) and suggesting genetics primarily determines protein percentage (Cannas and Pulina, 2008).
Lactose content was unaffected by treatments (p > 0.05), with averages slightly below the Normative Instruction No. 37 minimum, yet milk quality remained uncompromised. Vilanova et al. (2008) reported similar lactose levels, highlighting a need for further research on national herds. Defatted dry extract (DDE) and MUN levels were consistent across treatments, aligning with Silva et al. (2006) and Zambom et al. (2007). Somatic cell count (SCC) averages indicated no mastitis, consistent with studies correlating SCC with mammary health (Andrade et al., 2001; Paape et al., 2001).
The rate of increase to peak production was slower with SBM+DDGS diets, as seen in studies using Wood's model (Jacopini et al., 2013; Gomes et al., 2012). DDGS-fed goats showed the lowest decline after peak lactation and yield, linked to slower mammary development and sustained peak yield levels (Capuco et al., 2003). SBM diets resulted in higher lactation persistency, improving efficiency and profitability (Capuco et al., 2003). The lactation curve reflects milk production variations, with peak production influenced by nutrition and cell count (Park and Lindberg, 2006). Gomes et al. (2012) confirmed higher yields with SBM diets, consistent with this study's findings.
CONCLUSION
Incorporating 12.28% DDGS and 6.60% SBM in Saanen goats' diets from kidding to 120 days is a viable feeding strategy. This mix maintains milk quality and does not affect dry matter intake, providing a protein-rich alternative to soybean meal. The lactation curve with DDGS was intermediate compared to the standard SBM diet. Nonetheless, DDGS helps reduce feed costs without compromising milk composition, making it economically beneficial for dairy goat production. Future research should explore optimizing DDGS levels to boost milk yield while retaining cost-effectiveness.
ACKNOWLEDGMENTS
This work was supported by the Brazilian National Council for Scientific and Technological Development (CNPq) and the Coordination for the Improvement of Higher Education Personnel (CAPES), which provided a scholarship to the first author (Finance Code 001).
REFERENCES
- ANDRADE, P.V.D.; SOUZA, M.R.; BORGES, I.; PENNA, C.F.A.M. Contagem de células somáticas em leite de cabra. Arq. Bras. Med. Vet. Zootec., v.53, p.396-400, 2001.
- CANNAS, A.; PULINA, G. Dairy goats feeding and nutrition. London: CAB Inernational, 2008.
- CAPUCO, A.V.; ELLIS, S.E.; HALE, A.S. et al. Lactation persistency: insights from mammary cell proliferation studies. J. Anim. Sci., v.81, p.18-31, 2003.
- FONSECA, W.J.L.; AZAVÊDO, D.M.M.R.; CAMPELO, J.E.G. et al. Effect of heat stress on milk production of goats from Alpine and Saanen breeds. Braz. Arch. Zootec., v.65, p.615-621, 2016.
- FREITAS, T.B.; RELLING, A.E.; PEDREIRA, M.S. et al. Effects of increasing inclusion of sodium hydroxide treatment on growth performance, carcass characteristics, and feeding behavior of steers fed 50% DDGS. J. Anim. Sci., v.95, p.371-378, 2017.
- GIGER-REVERDIN, S.; DOMANGE, C.; BROUDISCOU, L.P. et al. Rumen function in goats, an example of adaptive capacity. J. Dairy Res., v.87, p.45-51, 2020.
- GOMES, L.C.; ALCALDE, C.R.; MACEDO, F.A.F. et al. Performance of lactating goats fed containing inactive dry yeast. Rev. Bras. Zootec., v.41, p.2249-2254 2012.
- GOMES, V.; LIBERA, A.M.M.P.D.; MADUREIRA, K.M.; ARAÚJO, W.P. Influência do estágio de lactação na composição do leite de cabras (Capra hircus). Braz. J. Vet. Res. Anim. Sci, v.41, p.339-342, 2004.
- HEIDELBERGER, P.; WELCH, P. Simulation run length control in the presence of an initial transient. Operations Res., v.31, p.1109-1144, 1983.
- JACOPINI, L.A.; LOURENÇO, D.A.L.; OLIVEIRA, C.A.L. et al. Comportamento da produção de leite de cabras Saanen e mestiças Boer-Saanen. Pubvet, v.7, p.1-11, 2013.
- MADUREIRA, K.M.; GOMES, V.; ARAÚJO, W.P. Physicochemical and cellular characteristics of milk from Saanen, Alpine and Toggenburg goats. Rev. Bras. Ciênc. Vet., v.24, p.39-43, 2017.
- NATIONAl Research Council nutrient requirements of goats. Seventh revised edition. Washington: National Academy Pres, 2007. 347p.
- PAAPE, M.J.; POUTREL, B.; CONTRERAS et al. Milk somatic cells and lactation in small ruminants. J. Dairy Sci., v.84 (E. Suppl.), p.237-244, 2001.
- PARK, C.S; LINDBERG, G.L. Glândula mamária e lactação. In: DUKES, H.H. Fisiologia dos animais domésticos. 12.ed. Rio de Janeiro: Guanabara Koogan, 2006. p.670-690.
- PONTES, V.P.; ALCALDE, C.R.; PILI, F.M.S. et al. Nutritive value of Saanen goat diets with dried distiller’s grains with solubles as replacement for soybean meal. Rev. Bras. Zootec., v.49, p.e20190279, 2020.
- ROSSI, R.M. Introdução aos métodos Bayesianas na análise de dados zootécnicos com uso do WinBUGS e R. Maringá: Eduem, 2011. 191p.
- SILVA, H.G.O.; PIRES, A.J.V.; SILVA, F.F. et al. Características físico-químicas e custo do leite de cabras alimentadas com farelo de cacau ou torta de dendê. Arq. Bras. Med. Vet. Zootec., v.58, p.116-123, 2006.
- STUANI, J.L.; CORASSA, A.; SILVA, I.P.A. Caracterização nutricional e uso de DDGS em dietas para suínos em crescimento e terminação - abordagem analítica. Rev. Nativa, v.4, p.116-120, 2016.
- VILANOVA, M.S.; GONÇALVES, M.; OSORIO, M.T.M. et al. Aspectos sanitários do úbere e composição química do leite de cabras Saanen. Acta Scient. Vet., v.36, p.235-240, 2008.
- WOOD, P.D.P. Algebraic model of the lactation curve in cattle. Nature, v.216, 164-165, 1967.
- ZAMBOM, M.A.; ALCADE, C.R.; GOMES, L.C. et al. Effect of soybean hulls on lactation curves and the composition of goat milk. Rev. Bras. Zootec., v.46, p.167-173, 2017.
- ZAMBOM, M.A.; ALCALDE, C.R.; HASHIMOTO, J.H. Parâmetros digestivos, produção e qualidade do leite de cabras Saanen recebendo rações com casca do grão de soja em substituição ao milho. Acta Scient. Anim. Sci., v.29, p.309-316, 2007.
Authors must select one of the following statements to indicate data availability: Data-available-upon-request - the research data are available upon request.
