Effects of dietary carbohydrates and buffering capacity on nutrient digestibility and manure characteristics in finishing pigs.

Abstract

A 2 x 3 factorial experiment was conducted with 24 finishing pigs (Yorkshire x [Finnish Landrace x Dutch Landrace]) to determine the effects of dietary buffering capacity (BC) and carbohydrate sources on apparent total tract digestibility (TD), N retention, and manure characteristics. Twelve of these pigs were fitted with steered ileo-cecal value cannulas to measure the apparent ileal digestibility (ID) of N. Experimental variables were two levels of BC (High = 600 mEq/kg and Low = 530 mEq/kg) and three dietary carbohydrates (tapioca [28%], soybean hulls [25%], and sugar beet pulp [25%]). The two levels of BC were achieved by adjusting the amounts of alkalogenic limestone and acidogenic Ca sulfate in the diet. Pigs were fed twice daily at 2.4 x maintenance requirement for metabolizable energy (418 kJ ME/BW(0.75)). Chromic oxide was used as an indigestible marker. Feces and urine were collected over 5 d for nutrient balance and in vitro measurements of pH and ammonia emission over 7 d. No significant interactions between BC and dietary carbohydrates on the ID, TD, N retention, or manure characteristics were observed. Lowering BC with Ca sulfate did not affect digestibility of most nutrients, except for a negative impact on the TD of Ca (P = 0.015) and Mg (P = 0.003). Although all pigs receiving Ca sulfate had more acidic urine (by 0.49 pH units; P = 0.001), ammonia emission from manure was not lowered, irrespective of the carbohydrate source. Carbohydrates affected significantly the ID and TD of most nutrients, whereas N retention remained similar (P > 0.10). Urinary N:fecal N ratios in manure of pigs fed diets with tapioca, soybean hulls, and beet pulp were 2.09, 1.35, and 1.67, respectively. These ratios corresponded with in vitro ammonia emission (169, 125, and 148 mmol/7 d; P = 0.023). In conclusion, these results indicate that the acidification of urine in pigs fed Ca sulfate in the presence of NSP-rich carbohydrates was achieved. However, acidity of manure and ammonia emission were not affected. The addition of NSP from soybean hulls and(or) sugar beet pulp reduced ratios of urinary:fecal N, and thereby ammonia emission.

Effects of increasing the intake of dietary β-glucans by exchanging wheat for barley on nutrient digestibility, nitrogen excretion, intestinal microflora, volatile fatty acid concentration and manure ammonia emissions in finishing pigs

“…This coincides with a linear increase in faecal N excretion and a numerical decrease in the urine : faeces N ratio as the level of dietary barley b-glucan increased. The effect of this is a shift in N excretion from its more volatile state as urea in urine to bacterial N in faeces (Mroz et al, 2000), thus limiting the capacity for rapid ammonia volatilisation.…”

“…However, if the level of NSPs available for microbial fermentation are increased, BCFAs, odour and ammonia levels are reduced (O'Connell et al, 2005;Garry et al, 2007). By increasing the carbohydrate to protein ratio entering the large intestine, nitrogen (N) excretion shifts from the more volatile urinary N to faecal N (Mroz et al, 2000;O'Connell et al, 2006), which is more stable.…”

The effect of cereal type and enzyme addition on pig performance, intestinal microflora, and ammonia and odour emissions

“…The effect of this is a shift in nitrogen excretion from urinary nitrogen to bacterial nitrogen in faeces (Nahm, 2003). This is desirable as it limits the capacity for rapid ammonia volatilisation (Mroz et al, 2000). Urinary nitrogen is excreted as urea which is converted to ammonia by bacterial ureases after mixing with faeces.…”

Feed ingredients differing in fermentable fibre and indigestible protein content affect fermentation metabolites and faecal nitrogen excretion in growing pigs

“…However, inclusion of fermentable DF (Awati et al, 2006) and reduction of protein (Htoo et al, 2007) in weanling diets reduces protein fermentation along the gastrointestinal tract. Moreover, the presence of fermentable DF in the diet can also reduce the emission of gaseous nitrogenous compounds by shifting N excretion from urine to faeces (Canh et al, 1997;Zervas and Zijlstra, 2002;Bindelle et al, 2009), thus reducing the NH 3 emission from piggery (Mroz et al, 2000;Nahm, 2003). O'Connell et al (2006) found increased urinary N and decreased faecal N when pigs were fed with barley-based fibre-rich diet, with significant interaction between protein levels, fibre source and enzyme supplementation on NH 3 emission.…”