Super-alimentation of gilts during lactation

Sows attempt to meet the sudden and large metabolic demand of lactation by increasing their level of voluntary food intake. However, the voluntary food intake of most sows during lactation generally does not provide sufficient energy or protein to meet their requirements for maintenance and milk production. By providing multiparous sows with extra food during lactation (via a gastric cannula) they remained in an anabolic state, and both milk production and piglet growth were increased (Matzat et al., 1990). Do gilts respond in the same way as sows to extra food in lactation? Gilts are smaller than sows and would be expected to have a greater impetus for body growth because they have not reached their mature body size. If gilts are provided with extra food during lactation, they might partition more of it into body tissue and less into milk. Gilts, fitted with gastric cannulas, were used to test the hypothesis that they would respond differently from the sows of Matzat et al. (1990) to extra food in lactation

Maintenance of villous height and crypt depth in piglets by providing continuous nutrition after weaning

Thirty-two piglets weaned at 28 days of age were used to test the hypothesis that maintenance of nutrition after weaning would prevent the normal decline in villous height and increase in crypt depth and hence preserve the structure and function of the small intestine. Piglets were allocated to one of four treatments at weaning: (1) control group killed at weaning; (2) piglets offered a dry starter diet ad libitum; (3) piglets offered ewes' fresh milk; and (4) piglets offered ewes' fresh milk plus 20 g t-glutamine per I. Piglets in treatments (3) and (4) were offered ewes' fresh milk every 2 h in a feeding schedule that increased from 1·2 I per piglet on the 1st day after weaning to 2·4 I on days 4 and 5. On the 5th day all piglets were killed and samples of small intestine were taken for histological and biochemical examination. Feeding ewes' milk or ewes' milk plus 20 g L-glutamine per I maintained (P > 0·05) villous height and crypt depth compared with piglets killed at weaning. In contrast, piglets given a dry starter diet had shorter villi (P 0·05) in their intestinal mucosa. Piglets given the starter diet proportionately grew from 0·49 to 0·62 more slowly (P 0·05), but consumed proportionately 0·30 less energy (P 0·05). Significant correlations existed between voluntary food intake and villous height at the proximal jejunum for piglets given the starter diet and ewes' milk (P < 0·05 and P = 0·073, respectively). In turn, villous height was significantly correlated (r = 0·78 to 0·87, P < 0·05) with the rate of body-weight gain after weaning in these two groups. For piglets offered ewes' milk plus glutamine, an increase in DM intake was associated only with increases in crypt depth (P < 0·01). These data show that the structure and function of the small intestine can be preserved when a milk diet is given after weaning, and suggest an association between food intake and villous height in determining post-weaning weight gain

Villous height and crypt depth in piglets in response to increases in the intake of cows' milk after weaning

The hypothesis tested in this experiment was that the structure and function of the small intestine of piglets given a milk liquid diet after weaning depends on their level of energy intake. At weaning (28 days), 42 piglets were allocated to one of five treatments: (1) control group killed at weaning; (2) piglets offered a dry starter diet ad libitum; (3) piglets given cow's fresh milk at maintenance energy intake (Ma); (4) piglets given cow's fresh milk at 2-5 Ma; and (5) piglets given cow's fresh milk ad libitum. On the 5th day all piglets were killed and samples of gut were taken for histological and biochemical examination. Piglets given milk ad libitum grew faster (P < 0·001) than piglets on all other treatments. Piglets offered the dry starter diet ingested similar quantities of dry matter and energy, and grew at the same rate as piglets given cows' milk at 2·5 Ma. As predicted, piglets given milk at maintenance energy intake grew slower (P < 0·001) and consumed less food (P < 0·001) than piglets in all other treatments. For piglets given both cows' fresh milk and the dry starter diet, there were significant linear relationships (r = 0·72 to 0·82, P < 0·05) between villous height and crypt depth with dry matter (energy) intake after weaning. In turn, mean villous height in both milk-fed and starter-fed piglets was significantly correlated (r = 0·68 to 0·79, P < 0·05) to empty body-weight gain in the first 5 days after weaning. Estimates of digestive enzyme activity and absorptive capacity of the gut did not corroborate the large differences seen between treatments in villous height and crypt depth, and possible reasons are discussed. These data illustrate the interdependence between voluntary food intake and mucosal architecture in determining piglet performance after weaning

Stomach cannulation of pregnant gilts for nutrition studies during lactation

The design, manufacture and insertion of a cannula into the stomach of first-litter gilts to facilitate superalimentation during lactation is described. Anaesthesia, surgery, and the presence of cannulas had no detrimental effects on birth parameters or on the gilts' ability to lactate and suckle their young. Stomach cannulation enabled us to infuse 37% more food into gilts during a 28-d lactation, and is an excellent research tool for manipulating nutrition during lactation

Feeding lactating primiparous sows to establish three divergent metabolic states: III. Milk production and pig growth

First-litter sows fitted with stomach cannulas were used to test the hypothesis that making gilts anabolic during lactation by providing them with extra nutrition would increase milk production and pig growth. Gilts were allocated to one of three dietary treatments after farrowing: 1) restricted, sows were fed 50% of their estimated ad libitum intake; 2) ad libitum, sows were encouraged to eat as much feed as possible; and 3) superalimented, sows were infused seven times daily through their cannula to achieve a 25 to 30% increase in energy intake in excess of that achieved by sows fed on an ad libitum basis. Milk production was estimated in mid- (d 10 to 15) and late (d 21 to 25) lactation by a modification of the isotope dilution technique. Milk production was similar between treatments in mid- and late lactation (P > .05), and this was reflected in a similarity in weaning litter weight (P = .238). Milk composition was similar also (P > .05) between dietary treatments. Superalimentation provided gilts with 38% more energy (P < .001) than gilts fed on an ad libitum basis, and they accrued live weight (5.1 kg) and backfat (1.8 mm) during lactation (P < .001). These data provide evidence that, unlike multiparous sows that show an increase in milk yield when made anabolic during lactation, primiparous sows seem to partition extra energy into body growth rather than into milk production

A modification to the isotope-dilution technique for estimating milk intake of pigs using pig serum

The aim of this study was to compare the measurement of deuterium oxide (D2O) directly in pig serum with that in sublimed whole blood. This was to assess whether excluding vacuum sublimation before analysis would cause any significant loss of accuracy in estimates of pig milk intake. Water and serum standards were made in deionized water and serum, respectively, and were assayed with samples under the same conditions on a fixed-filter, infrared spectrophotometer. The mean concentration of D2O in sublimed samples was 2,244 microg/mL of body water, and the mean concentration of D2O in serum samples was 2,184 microg/mL of body water. The mean ratio of D2O concentration in deionized water to the D2O concentration in serum was 1.0275, which was used as a correction factor to convert serum D2O concentration to D2O concentrations in body water. Using this method, the mean concentration of D2O in all serum samples was identical to that in sublimed samples (i.e., 2,244 microg/mL of body water). Mean milk intake of pigs based on sublimed samples was 1,006 g/d and that based on serum samples was 1,012 g/d. This confirms that milk intake determined from measurement of D2O directly in pig serum is sufficiently precise

Feeding lactating primiparous sows to establish three divergent metabolic states: II. Effect on nitrogen partitioning and skeletal muscle composition

We established an experimental model to study nitrogen (N) partitioning in lactating primiparous sows alimented to three levels of nutrient intake. Thirty-six sows fitted with a gastric cannula and fed a 15.4 MJ DE/kg and 18.6% CP diet were allocated to one of three treatments after farrowing: 1) ad libitum-fed; 2) restricted-fed to 55% of the ad libitum feed intake; and 3) superalimented to at least 125% of the ad libitum feed intake. These feed intakes were successfully achieved throughout lactation. Nitrogen balance was studied for three 5-d periods starting on d 2, 11, and 19 of lactation, and a triceps muscle biopsy was taken on d 26. For all treatments, N intake increased, milk N production increased, urinary N losses decreased, but fecal N losses increased as the 28-d lactation progressed. Restricted-fed sows had the lowest fecal N and urinary losses and mobilized the most maternal protein (-23.0 vs -7.4 +/- 6.5 g N/d for ad libitum-fed sows) during lactation. As a consequence of these economies, and extensive protein mobilization, restricted-fed sows were able to maintain milk N production similar to that of sows on the other treatments. Superalimented sows did not mobilize protein, had the poorest protein digestibility, directed the least digestible N toward milk (40.1 vs 78.3% in restricted-fed sows), and produced amounts of milk N similar to those produced by sows on the other treatments. The treatment differences in N retention measured by N balance were reflected in differences in skeletal muscle variables and urinary creatinine. Skeletal muscle cell size (protein:DNA ratio) and protein synthetic capacity (RNA:DNA ratio) increased in response to feed intake. The protein:DNA ratio increased (P < .01) linearly and the RNA:DNA ratio increased (P < .05) in a curvilinear manner. These data suggest that primiparous sows partition additional retained N toward their maternal reserves rather than milk N. They also suggest that sows fed inadequate N intakes maintain milk production by mobilizing maternal protein reserves. Such sows also conserve maternal N during lactation, possibly by reducing muscle protein synthesis