The effects of feeding formaldehyde-treated canola meal in two levels of dietary crude protein on dry matter intake, milk yield and composition, nutrients digestibility and ruminal parameters in lactating goats

Due to relative cost and dependence of the country on soybean meal imports, more attentions are given to new protein sources such as canola meal as a suitable alternative for soybean meal. Also, high protein degradability of meals in the rumen lead to loss of nitrogen (urea) through urine. Thus, meal processing methods are considered in order to reduce the rate of ruminal protein degradation and increase by-pass protein proportion which can improve animal productive performance and efficiency of nitrogen utilization. Therefore, the effects of substituting formaldehyde-treated canola meal (0.8 and 1.2% of meal crude protein) for untreated meal on feed intake, nutrient digestibility, productive performance and some ruminal parameters in lactating goat’s diet, and the possibility to compensate dietary protein deficiency using processed meal with 1.2% formaldehyde was investigated in this study.

Eight multiparous lactating goats with initial milk yield of 650-700 g/d were used in this study. Canola meal was treated with formaldehyde at two levels of 0.8 and 1.2% CP of meal and then used in the concentrate mixture. Four dietary treatments were: (1) control diet with 14.5 % CP containing untreated canola meal, (2) diet with 14.5 % CP containing formaldehyde-treated canola meal (0.8% CP), (3) diet with 14.5 % CP containing formaldehyde-treated canola meal (1.2% CP), and (4) diet with 12.5 % CP containing formaldehyde-treated canola meal (1.2% CP). In the last 7 days of each experimental period, feed intake and milk yield were measured daily and a subsample of produced milk was collected for milk component analysis. On the last day of each collection period, ruminal fluid samples were taken from goats to measure pH, NH3-N concentration and protozoa population count. Gross profit of milk production and economic estimation of experimental diets were also performed.

The DM intake of the goats was significantly increased by substitution of formaldehyde-treated canola meal in the diet (P<0.05), also reducing dietary CP level had the same effect. Feeding 1.2 % formaldehyde-treated canola meal only, or with reduced CP level of diet significantly increased production of milk, FCM, and fat, protein, lactose (P<0.05) while experimental diets had no effect on milk composition of the goats. Treating canola meal with formaldehyde did not affect ruminal pH, total protozoa, and Entodiniomorph, Holotrich and Cellulolytic count, while NH3-N showed a significant decrease by feeding 1.2% formaldehyde-treated canola meal at 3h post-feeding (P<0.05). Mean daily feed cost increased by feeding formaldehyde-treated canola meal and daily gross profit were higher with groups fed diets containing 1.2% formaldehyde-treated canola meal.

Due to present results, formaldehyde treatment of canola meal (1.2 %) enhanced feed intake and productive performance of lactating goats, moreover, treatment at this level had properly compensated the probable adverse effects of the lack of dietary crude protein on animal performance, overally. Therefore, formaldehyde treatment of canola meal (1.2 %) is recommended as a suitable choice to increase dietary bypass protein and positively impact productive performance, also to reduce the loss of nitrogen from body.