Effect of Diets Varying in Dietary Cation-Anion Difference Fed in Late Gestation and in Lactation on Sow Productivity1, The

Professional Animal Scientist, Apr 2008 by Roux, M L, Johnston, S L, Lirette, R D, Bidner, T D, Southern, L L, Jardon, P W

ABSTRACT

Eighty-six primiparous or multiparous sows and their pigs were used to evaluate the effects of changing DCAD in late gestation and in lactation on sow productivity. Sows were allotted to treatment based on parity and their farrowing date. Experiment 1 was a preliminary experiment conducted to determine the level of DCAD that would reduce urinary pH. Twenty sows were used in Exp. 1, and the dietary treatments consisted of a corn-soybean meal diet with 4 levels of DCAD (140, 103, 80, and 56 mEq/kg). These DCAD were achieved by addition of 4 levels of chloride (SoyChlor; 0, 1.5, 2.5, and 3.5% of the diet). The diets were fed from d 107 of gestation to weaning. Urinary pH was linearly decreased (P

Key words: electrolyte balance, reproduction, sow, urinary pH

INTRODUCTION

Dietary cation-anion difference is the difference between strong fixed cations and strong fixed anions. These differences in dietary strong cations and anions will indicate whether the diet will elicit an alkaline or acidic metabolic response, respectively, when fed to the animal.

SoyChlor (West Central, Ralston, IA) is an anionic salt feed additive that is commonly fed to dairy cattle to make the diet more acidic, thereby reducing the incidence of milk fever (parturient paresis). Cows affected with milk fever have reduced feed intake, reduced urination and defecation, and if left untreated, become comatose and die (Horst et al., 1997). Milk fever contributes to a severe economic loss because milk production declines in the subsequent lactation (Block, 1984) and medication costs for treatment increases (Block and LeClerc, 1989). Changing dietary electrolyte balance has been shown to have positive effects on adaptive stress in broilers (Olanrewaju et al., 2007). Sows usually are not affected with milk fever, but urinary tract infections can reduce herd health and cause the swine industry to suffer economic loss due to reduced herd health. The purpose of this research was to determine if reducing DCAD in the diets would affect sow productivity when fed during late gestation and in lactation.

MATERIALS AND METHODS

The Louisiana State University Agricultural Center Animal Care and Use Committee approved all methods used in these experiments. Primiparous and multiparous Yorkshire and crossbred (Yorkshire � Landrace or Yorkshire � Duroc) sows from the Louisiana State University Agricultural Center Swine Unit were allotted to dietary treatments on d 107 of gestation for Exp. 1 and d 111 of gestation for Exp. 2. Before starting dietary treatments, all sows were fed a typical corn-soybean meal gestation diet that met or exceeded the nutrient requirements (NRC, 1998) of gestating sows. The sows were allotted to their respective treatments within each farrowing group based on parity and the date of d 107 of gestation for Exp. 1 and d 111 of gestation for Exp. 2.

The sows were penned in a mechanically ventilated farrowing house with 28 individual farrowing crates and an under-floor flush system. Cooling was achieved by drip-coolers and fans, and heating was achieved by natural gas heaters. The experiments were conducted from April 2004 to May 2005. The farrowing crates were 1.5 � 2.1 m with a cast iron-floor for the sow and plastic slotted floor for the pigs. Each crate contained a stainless steel feeder and nipple waterer for the sow and a nipple waterer for the pigs. Within 24 h of farrowing, litters were weighed, earnotched, given a 1-mL shot of iron dextran (Phoenix Scientific Inc., St. Joseph, MO), umbilical cords were sprayed with iodine, and needle teeth were clipped. During processing, litters were also adjusted by cross-fostering within respective treatments to approximately 10 pigs per litter if necessary.

Treatment diets (Table 1) fed during both experiments were formulated on a total amino acid (AA) basis from analyzed AA values for SoyChlor and NRC (1998) values for corn and soybean meal. Proximate analysis (CP, ash, moisture, crude fat, and crude fiber) and NDF were conducted on SoyChlor for calculation of ME [NRC, 1998; ME = 1,107 (0.64 � ME) (22.9 � % ether extract) (6.9 � % CP)]. The nutrient content of SoyChlor was determined as follows using AOAC (2000) methods (Table 2): AA [Official Method 982.30 E (a,b,c)]; CP (Official Method 990.03); Kjeldahl [Official Method 984.13 (A-D)]; ash (Official Method 942.05); crude fat by ether extraction [Official Method 920.39 (A)]; crude fiber (Official Method 978.10), and moisture (Official Method 934.01). Minerals were determined by inductively coupled plasma-optical emission spectoscopy sequential inductively coupled plasma-optical emission spectroscopy. The diets were formulated to contain 3,300 kcal/kg ME and 1.02% total Lys. The diets met or exceeded 105% of the requirement (NRC, 1998) for lactating sows, anticipating no lactation weight loss with pigs gaining 250 g/d. Sows were fed the treatment diets from the time they were moved into the farrowing house until weaning. Upon entering the farrowing house until d 1 postfarrowing, the sows were fed approximately 2.5 kg/ d, but feed refusals were recorded. On d 1 postfarrowing and throughout lactation, sows were fed 3 times per day to attempt ad libitum intake.