WHOLE AND PROCESSED COTTONSEED WITH ADDED FIBER ON RUMEN VARIABLES, MILK PRODUCTION AND COMPOSITION pdf

WHOLE AND PROCESSED COTTONSEED WITH ADDED FIBER ON RUMEN VARIABLES, MILK PRODUCTION AND COMPOSITION by BENJAMIN FINIS SULLIVAN, B.S.. EFFICACY OF WHOLE AND PROCESSED COTTONSEED ON DIGEST

WHOLE AND PROCESSED COTTONSEED WITH ADDED

FIBER ON RUMEN VARIABLES, MILK

PRODUCTION AND COMPOSITION

by BENJAMIN FINIS SULLIVAN, B.S

A THESIS

IN ANIMAL NUTRITION

Submitted to the Graduate Faculty

of Texas Tech University in

Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE

Approved

August, 1984

ACKNOWLEDGMENTS

I would like to express my deep appreciation to Professor

C Reed Richardson for his guidance and support of this thesis and

to the members of my committee Professors Mark Hellman, Max Miller and John Anderson, for their suggestions and advice

I would also like to dedicate this thesis to my wife, Karita, whose love, support and sacrifice allowed me to pursue this endeavor and to whom I will always be grateful

1 1

TABLE OF CONTENTS

Page ACKNOWLEDGMENTS ii LIST OF TABLES iv

I INTRODUCTION 1

II LITERATURE REVIEW 3

Effects of Whole Cottonseed 3 Effects of Added Dietary Fat 8 Cottonseed Meal 16

III EFFICACY OF WHOLE AND PROCESSED COTTONSEED ON

DIGESTIBILITY, RUMEN VARIABLES AND THE PRODUCTION

OF MILK AND ITS COMPONENTS 20 Summary 20 Introduction 21

Materials and Methods 22 Results and Discussion 29 LITERATURE CITED 40

1 1 1

Table Page

1 Composition of Diets—Exp 1 23

2 Nutrient Composition of Feed Ingredients—Exp 1 24

3 Composition of Diets—Exp 2 26

4 Nutrient Composition of Feed Ingredients—Exp 2 27

5 Composition of Seed Pellets 28

6 Milk and Butterfat Production of All Cows—Exp 1 30

7 Milk and Butterfat Production of Cows Supplying Data to

All Three Periods—Exp 1 30

8 Milk and Butterfat Production of Cows in First

Lactation—Exp 1 31

9 Dry Matter Intake of Hay, Total Diets and Digestible

Energy—Exp 1 32

10 Milk Production and Composition, Average Weight Gain,

Dry Matter Intake and Feed Efficiency—Exp 2 34

11 Apparent Digestibilities, Rumen VFA and pH—Exp 2 35

12 Mean Fatty Acid Composition of Milk Fat—Exp 2 37

IV

CHAPTER I INTRODUCTION

Cotton is one of the world's most important agricultural,

nonfood commodities accounting for more than 49.5% of the total

fiber production (natural and man-made) in 1980 (1982 World Almanac) Gossypium hirustum (produces medium-staple fibers) is one of the

two most economically important species of cotton cultivated in the United States In west Texas G hirustimi has been used as a dry-land crop in areas where reduced water tables and(or) high fuel costs

have prevented economical irrigation

Upon harvesting, cotton must be processed through a cotton gin

to separate the cotton fibers from the seed, leaves, stems and dirt Whole cottonseed (WCS), as it comes from the gin, may be processed further to produce a number of eonomically important products Cot-tonseed oil, extracted from the seed by either solvent or mechanical processing, is used in several food products including margarine,

shortening, cooking and salad oils The two remaining products after oil extraction, cottonseed meal (CSM), and hulls (CSH), are used as protein and fiber sources, respectively, in ruminant feeds Linters, the short cellulosic fibers adhering to the seed after ginning, can

be removed by treating the seed with acid to produce delinted seed (DLCS), used for planting The linters are used as mattress

cotton-and upholstery stuffing, in the production of coarse cotton yarns

and upon purification, linters form the base for cellulose

deriva-tives for the manufacture of explosives, paints, plastics and film

dairymen throughout the Southwest as a source of protein, fat, fiber and phosphorous Economic pressures and the benefit in production many dairymen associate with WCS feeding has created a renewed inter-est in the feeding value of whole cottonseed However, problems of freight cost, handling, and storage associated with WCS, because of its bulky, fibrous nature, could be alleviated by pelleting if the cost of production and(or) effects on livestock production do not prohibit its use

CHAPTER II LITERATURE REVIEW

Effects of Whole Cottonseed Milk Components

The effects of feeding WCS on the production of milk and its

components have been quite variable In a recent study by Anderson

et _al (1984) cows were fed rations containing 10% WCS, 5% extruded soybean (ESB), or 12% whole sunflower seed (WSS), dry matter (DM)

basis Cows receiving WCS produced more (P<.05) milk, 4%

fat-cor-rected milk (FCM) and protein than cows fed whole sunflower seed

Milk fat percent and fat production were higher (P<.05) for the WCS diet compared to the ESB or WSS diets But when WCS was fed at 18.5%,

DM basis, replacing an isonitrogenous amount of a corn silage based ration, milk production, percentages of milk fat and protein were

unaffected (Hawkins et al., 1982) In a fifteen week experiment

(Hansen, 1980) Holstein cows received rations with 7% ESB or WCS

fed at 15% or 30% The WCS treatments increased percent milk fat, but decreased milk production, percent solids-not-fat, (SNF) and

protein A related study (Hansen, 1980) involving 55 commercial

dairy herds fed various levels of WCS resulted in no difference in fat, protein or SNF content of the milk

Anderson e^ aJ^ (1979) fed WCS in two experiments In the first experiment, when WCS replaced 1.9 kg of the concentrate in an alfalfa hay (ad libitum), corn silage and concentrate diet, cows fed WCS

produced more (P<.05) milk, fat, FCM and SNF than controls There

3

percent protein was lower (P<.05) for the WCS diet In experiment

two diets were: (1) control; (2) 20% replacement of concentrate

with WCS; and (3) control diet but isocaloric to diet two Corn

silage was fed at 9.1 kg/hd/d and alfalfa ad libitum There were

no differences (P>.05) in FCM production or percent composition of

milk fat or protein among treatments Cows on rations two and three produced more (P<.05) milk and SNF than controls and had a higher

percentage of SNF in their milk In three experiments conducted

in Hawaii (Stanley ^ aJ^., 1969), where restricted fiber intake and

a warm climate appear to affect low solids and fat content in milk, five pounds of WCS replaced six pounds of concentrate in isocaloric diets Cows fed WCS in the three experiments had higher (P<.05)

fat production and percent composition of fat than controls In

the third, conducted at a commercial dairy, lower (P<.05) milk yields occurred in cows on the WCS diet

Moody (1968) replaced part of a control diet with 2.27 kg WCS, 1.13 kg CSM, acidulated soap-stock from cottonseed replacing 4% milo

in the concentrate, 5% CSH, or acidulated soap-stock and 5% seed hulls There were no differences in milk yield, SNF or protein due to treatment Percent fat was highest for the WCS diet followed

cotton-by the CSM diet When WCS replaced a CSM and corn mixture in the

concentrate on an equal weight basis, cows produced more milk (P<.05), FCM (P<.01) and percent fat (P<.01) (Ramsey and Miles, 1953) The replacement of two lb of a barley, wheat bran and CSM control ration

by two lb of WCS resulted in an average decrease of 12 lb milk,

.06% serum solids and an increase of 21% fat (Davis and Harland, 1946) When two lb of WCS replaced 2 lb of CSM in a basal ration, cows fed CSM produced, on the average, more milk and fat than cows

on whole cottonseed (Lush and Gelpi, 1932)

Moody and Barnes (1966) studied the effects of WCS and crude cottonseed oil against a control while varying alfalfa hay levels

at either 1.25 kg/100 lb body weight or 2 kg/100 lb body weight

There were no significant differences in milk production, SNF or protein among treatments Cows fed WCS and alfalfa hay at either rate produced significantly more milk fat In limited fiber rations (Moody and Cook, 1961), alfalfa hay was fed at one lb/100 lb body

wt, 1.5 lb/100 lb body wt, or ad libitum Whole cottonseed was fed

at 22% of a grain concentratẹ Cows fed hay at one lb/100 lb body

wt had significantly higher percent fat and FCM production than cows

on the other rations

Feed Consumption, Digestibilities, and Weight Gain

Dry matter intake of cows fed WCS at 1.9 kg/hd/d (Anderson

^ aJ^ , 1979) was higher (P<.05) than of cows fed a control diet

in experiment onẹ Results of DM or digestible energy intake were not different (P>.05) in experiment twọ A lack of significant dif-ference in DM intake is in agreement with Smith et^ ậ (1981) and Hawkins et_ jl (1982) Dry matter intakes of cows receiving 10% WCS were lower (P<.05) than cows offered 5% ESB, but higher (P<.05) than cows fed 12% whole sunflower seed (Anderson et jl., 1984)

Cows fed WCS to replace CSM in rations where Johnson or Sudan grass

silage but more (P>.05) hay (Ramsey and Miles, 1953) These results are in agreement with Lush and Gelpi (1932) Hawkins et al (1982) reported less (P<.10) total feed consumption of a corn silage based ration with WCS fed at 18.5%

Substitution of WCS in a basal diet increased (P<.05) bilities of nitrogen (N), energy and ether extract (EE) (Smith et^ al., 1981), but did not produce significant effects in digestibility

digesti-of DM (Smith et^ al., 1981 and Anderson et^ al^., 1984) or crude and acid-detergent fiber (ADF) nor on net Ca, P, or Mg absorption (Smith

et al., 1981) Keele and Roffer (1982) reported no effect on total organic matter (OM) digestibility, increased apparent ruminal and total digestibility of N and decreased apparent OM digestibility

Changes in body weight gains reported by several workers were not significantly affected by WCS feeding (Ramsey and Miles, 1953; Moody and Barnes, 1966; Moody, 1968; Anderson et_ al^ , 1979; Hawkins e^ al., 1982) Weight changes reported by Anderson ^ al (1984) were not different (P>.05) but there were tendencies towards greater weight gain in cows fed ESB or whole sunflower seed Body weight gains were significantly lower in cows fed WCS and offered hay ad libitum compared to cows receiving hay at restricted levels (Moody and Cook, 1961)

Volatile Fatty Acids And Free Fatty Acids

The three major rumen volatile fatty acids (VFA), acetic, pionic, and butyric, were not altered (P>.05) in cows fed WCS com-

pro-pared to a control and energy equivalent ration Whole cottonseed feeding, however, did result in tendencies toward higher acetic and lower propionic acid concentrations (Anderson et al., 1979) Moody and Barnes (1966) reported nonsignificant increases in total VFA

on high roughage rations and higher acetic:propionic ratios from cows fed WCS vs cottonseed oil and control diets

Whole cottonseed fed at varying levels in a feeding study with

55 commercial dairy herds and a digestibility study (Smith £t al^., 1981) resulted in significantly altered levels of milk free fatty acids (FFA) Although WCS contains 15% oleic (C18:l) and 62% lin-oleic (C18:2) by weight of the total lipid content of WCS, results showed up to a fourfold increase of C18:l yields and no effect on C18:2 yields in the milk Yields of the short chain fatty acids (FA), C6:0 to C12:0, and C6:0 to C14:0, were depressed in the di-gestibility and feeding study, respectively, when V7CS was fed The percent by weight of short chain fatty acids decreased with subse-quent increases of stearic (C18:0) and C18:l fatty acids as feeding levels of WCS increased in the diets Net increases of percent and yield of milk fat resulting from transfer of WCS fat as de novo syn-thesis of fatty acids was reduced by as much as 50% These results are supported by Keele and Roffler (1982), who reported increased duodenal flow rates of palmitic, C18:0 and C18:l FA over other FA

in cows fed whole cottonseed The increased duodenal flow rates

of C16:0, C18:0 and C18:l and increased milk yields of C18:0 and C18:l indicate high rimien lipolysis and biohydrogenation of CIS:2 (Smith et al., 1981; Keele and Roffler, 1982)

Effects of Added Dietary Fat Fat, because of its high energy density, may be added to dairy

rations in attempts to better balance rations for high producing

cows, restricted in energy and(or) fiber Research has been

con-ducted in recent years to determine more extensively the effects

additional dietary fat have on the production and composition of

milk

Milk Yields and Milk Components

The use of a concentrate containing 5% unprotected fat to

in-crease DM EE from 3.2% to 8.3% resulted in inin-creased (P<.05) milk

yields in second lactation cows considered to have a high genetic

level of production Milk production of second lactation cows, with

a low genetic level for production, was increased (P<.10) on the high fat concentrate There was not a response in first lactation cows

due to treatment (Mattias et_ al., 1982) Feeding an animal-vegetable fat blend in a high fat diet (6% fat vs 3% fat, DM) resulted in an

increase (P<.05) in milk yield and a subsequent decrease (P<.01)

in milk fat percent in high producing cows In low producing cows, milk production was not altered significantly but percent milk fat

was depressed (P<.01) Production of 3.5% FCM was not different

(P<.05) between groups (Heinrichs ^ jJ^ , 1981) Palmquist and rad (1980) reported decreased (P<.01) production of milk, FCM, fat

Con-and protein in cows fed 10% tallow in a grain concentrate fed at 50%

DM compared to cows receiving 10% hydrolyzed fat in grain fed at 50% and 33% DM or grain fed at 33% containing 10% tallow Palmquist and

Conrad (1978) conducted two trials using hydrolyzed animal fat In trial one hydrolyzed fat, at two levels, was compared to a control and ground raw soybeans in diets ranging from 2.9 to 10.8% in total diet EE (DM) Milk yield, fat and protein were not different (P>.05)

In trial two, hydrolyzed fat was fed in high fat diets of 5.9 and

6.8% total dietary EE compared to low fat diets with 3.3 and 2.9%

ether extract Cows receiving the two high fat diets produced more (P<.05) percent and yield of milk fat Cows on the 6.8% EE diet

produced more (P<.05) FCM than cows on the low fat diets Milk and protein production were not affected (P>.05) Rations containing

5.2% fat produced significant increases in percent milk fat, slight increases in 4% FCM and no increase in milk yield compared to a ration containing 2.7% fat (Byers et al., 1949)

A protected tallow supplement (60% formalin treated soybean meal and 40% tallow) was fed at 0, 15 and 30% (Smith ^ al^ , 1978) to

Holstein cows during the first 15 weeks of lactation The protected fat supplement resulting in a decrease (P>.05) in milk production,

and an increase (P<.05) in 4% FCM, percent and yield of milk fat and

a decrease (P<.05) in percent and yield of SNF compared to controls These results became greater as fat levels increased A significant decrease in SNF was reported by Souleimani et^ al (1982) from feeding

a hydrogenated vegetable fat supplement The feeding of formaldehyde treated safflower or soybean oils resulted in an increase in the total solids (TS) content of the milk Unprotected safflower oil and pro-tected hydrogenated soybean oil depressed milk total solids Protect-

ed, unsaturated soybean oil and protected coconut oil increased

(P<.05) percent milk fat and protein (Astrup £t al., 1976) Mattos and Palmquist (1974) reported increases of milk yield (P<.01), per-

cent (P<.05) and yield (P<.001) of milk fat and a decrease (P<.05)

in milk crude protein in cows supplemented with 3.6 kg of either

unprotected or formaldehyde-protected full-fat soyflour

Digestibility, DM Intake And Body Weight Change

Palmquist and Conrad (1978) reported trends towards increased

digestibility of DM, energy, ADF and calcium (Ca) due to fat feeding

in trial one Digestibility of EE was increased (P<.05) in diets

containing fat Nitrogen digestibility was increased on medium fat (P>.05) and on high fat diets (P<.05) Magnesium digestibility was higher (P<.05) for the medium fat diet consisting of raw ground soy-beans over the high fat and control diets In trial two, digesti-

bility of DM, energy and magnesium was not affected (P>.05) by

treatment Digestibility was higher for ADF (P>.05) and EE (P<.05)

in high fat diets but lower (P>.05) for calcium Diets containing

tallow or hydrolyzed fat (Palmquist and Conrad, 1980) had higher

(P>.05) digestibility coefficients for EE and ADF over the control

diet Energy, N and DM digestibility was lower (P>.05) in one ration with grain fed at 33% containing 10% hydrolyzed fat compared to the control diet Unprotected full-fat soyflour, in a study by Mattos

and Palmquist (1974), increased (P<.05) DM digestibility compared

to control and protected soyflour diets Digestibilities were higher for EE (P<.05) and ADF (P>.05) from diets containing high fat levels

11 Nitrogen digestibility was lower (P<.05) on the protected soyflour

diet

Heinrichs et al (1981) reported no difference (P>.05) in DM,

crude protein, ADF or Ca intakes associated with feeding diets

con-taining 3 or 6% fat Dry matter intake and body weight were not

affected (P> 05) from supplementation with oleic acid, Crisco or

a fat high in C18:l trans fatty acid (Sulner and Shultz, 1980)

These results are in agreement with Palmquist and Conrad (1978)

using ground, raw soybeans and hydrolyzed animal fat in Jerseys,

Palmquist and Conrad (1980) feeding an animal-vegetable fat blend

and Souleimani et al^ (1982) feeding a hydrolyzed vegetable fat

In a second trial (Palmquist and Conrad, 1978) DM intake was not

altered (P>.05) but cows fed a high fat, high protein diet did have

lower (P<.05) body weight changes than cows on a low fat, high

pro-tein diet Smith et al (1978) found depressed (P<.05) DM intake

in cows fed a high fat (protected tallow) supplement without any

change (P>.05) in body weight Mattias et al (1982) fed a

concen-trate diet containing 5% animal fat and reported no significant

changes in body weight Inclusion of WSS at 10, 20 and 30% as a

source of dietary fat to Holstein heifers did not affect (P>.05)

body weight gains but did suppress (P<.05) DM consumption resulting

in improved (P<.05) feed efficiency (Park and Rafalowski, 1983)

VFA And FFA Production

Studies have been conducted on the effects of feeding fat, in

various forms in order to better understand events which lead to

depressed milk fat synthesis in dairy cattle

Van Soest (1963) discussed three theories to explain depression

of milk fat concentration: 1) deficiency of rumen acetic acid;

2) deficiency of beta-hydroxybutyric acid; and 3) a decline in blood lipids required for milk fat synthesis resulting from a glucogenic

response during high propionate production on high concentrate diets, suppressing tissue fat mobilization A deficiency of rumen acetic

acid caused by feeding ground roughage or high concentrate diets

was substantiated by cited work which described a decrease in the

Reichert-Mersial number of the milk fat from cows receiving restricted roughage or high concentrate diets and a return to near normal fat

composition as a result of feeding acetic acid or acetate salts

Brown et^ _al^ (1962) found decreased (P<.05) molar percent of rumen

acetate in cows fed a low roughage diet However, Bauman et al

(1971) reporting decreases in percent milk fat and molar ratio of

acetate:propionate attributed these findings to an increase in

pro-pionate production rather than a decrease in acetate This is in

agreement with McCullough (1966) The increase in rumen propionate

concentrations leads to increased lactate and glucose production,

stimulating insulin production, resulting in a reduction in the

re-lease rate of adipose free fatty acids Milk fat synthesis is

de-pressed due to a decrease in availability of preformed long chain

FA to the mammary gland (Christie, 19 79)

Dietary fat interferes with microbial activity, affecting VFA

production (Astrup et^ al•, 1976) Several workers have reported

a decrease (P<.05) of the acetate:propionate ratio in cows fed an

13 unprotected, unsaturated fat as a result of decreased (P<.05) ace-

tate concentrations (Mattos and Palmquist, 1974; Palmquist and

Con-rad, 1978; Seiner and Shultz, 1981) and increased propionate

(Palm-quist and Conrad, 1978; Seiner and Shultz, 1981) This does not

agree with Brown et al (1962) who, although he reported a

depres-sion in acetate levels (P>.05) associated with tallow and cottonseed oil feeding, found increases in valerate and higher acids for tallow (P>.05) and cottonseed oil (P<.05) in cows on low roughage diets

Acetate:propionate ratios have not been affected (P>.05) when

hydro-genated fats (Palmquist and Conrad, 1978; Seiner and Shultz, 1981)

and protected oils (Astrup ^ ^ 1 , 1976) or fat (Mattos and Palmquist, 1974) have been fed Palmquist and Conrad (1980) found differences (P<.05) in rumen propionate concentrations to be associated with

dietary fiber level and not from feeding either tallow or

hydrogen-ated vegetable oil

Milk fat depression occurs from shifts in rumen ate ratios inducing a glucogenic response from adipose tissue, causing

acetate:propion-it to: 1) compete wacetate:propion-ith the mammary gland for lipogenic substrate,

thereby reducing availability of acetate to the mammary gland; 2)

absorb and esterify increased amounts of long chain FA; and 3)

de-crease mobilization of adipose long chain FA to the mammary gland

for milk fat synthesis (Palmquist and Jenkins, 1980) The decreased mobilization of adipose FA would, however, have a minimal effect,

as less than 10% of milk FA are from adipose tissue Approximately 50% of milk FA are from de novo synthesis in the mammary gland uti-

lizing acetate and beta-hydroxybuterate and 40-45% contributed by

dietary sources (Mattos and Palmquist, 1978)

Palmquist and Jenkins (1980) summarized factors affecting rumen effects on fat sjoithesis Fatty acids in conventional diets are

mostly esterified and usually rapidly hydrolyzed by rumen lipolytic bacteria The biohydrogenation of unsaturated FA is dependent on a

free carboxyl to obligate lypolysis as the initial step, which,

al-though rapid, may be the rate limiting step depending on whether the

FA precursor is esterified Increases of unsaturated FA

concentra-tions in the milk, particularly C18:2, can occur as a result of

de-creased populations of lipolytic and biohydrogenating organisms from high grain-low roughage diets A source of long chain fatty acids

includes rumen protozoa and bacteria, both capable of de novo

syn-thesis of long chain FA, utilizing precursors with odd or even chain carbons or containing branched chains Modification of FA chain

length occurring by alpha and beta oxidation De novo synthesis

may be inhibited by dietary fatty acids, absorbed in cellular lipids

of rumen microorganisms and occurring as membrane phospholipid and

unesterified fatty acid Data supporting the theory of fat as an

inhibitory agent affecting rumen microbial activity on fiber

diges-tibility include inhibition of rumen bacteria in pure culture by

FA (Hartfoot, 1978; Maczulak, 1979) and binding of FA to microbial

cells (Nieman, 1954; Henderson, 1973; Maxcy and Dill, 1976) reduced

by adding fiber (Hartfoot £t^ al., 1974), reducing inhibition in pure cultures (Maczulak, 1979) Unsaturated fats, particularly polyun-

saturates, inhibit microbial growth (Palmquist and Jenkins, 1980)

and are more toxic to rumen microbes than saturated fats (Galbraith

15 and Miller, 1973; Henderson, 1973; Maczulak, 1979) Dietary unes-

terified FA, particularly lineoleate, may also inhibit rimien

biohy-drogenation (Moore e t a l , 1969)

Mattos and Palmquist (1974) reported decreases (P<.05) of milk

C6:0 to C16:0 FFA with increases (P<.05) of C4:0 and all C18 FFA

from cows fed protected or unprotected fat Free fatty acid

concen-trations of C18:0 and C18:l were lower (P<.05) on the protected fat supplement compared to the unprotected supplement The authors sug-

gested less ruminal biohydrogenation of the protected supplement

Decreases (P<.05) of C8 to C14 FA and increases (P<.05) of C4 and C16

to C18:l FA resulted in cows fed a 15% protected tallow supplement

(Smith et al , 1978), an additional significant decrease and increase

in C6 and C18:2 respectively from the 30% tallow diets The decrease

of the short chain FFA is possibly explained by the increased mammary gland uptake of long chain FA inhibiting de novo synthesis of short

chain FA in the mammary gland by feedback inhibition of the long

chain acyl-CoA carboxylase (Mattos and Palmquist, 1974) The

in-creased yields of milk butyric acid may be due to a partial or

com-plete independence of the malonyl CoA synthetic pathway (Mattos and

Palmquist, 1974); or decreased utilization as a precursor for FFA

chain elongation resulting from suppressed mammary de novo FA

syn-thesis (Mattos and Palmquist, 1974; Smith et al., 1978) Similar

results have been reported for cottonseed oil and tallow (Brown et^

al., 1962), ground raw soybeans and hydrolyzed fat (Palmquist and

Conrad, 1978), a supplement high in linoleate (Young et^ al•> 1978), oleic acid and hydrolyzed vegetable fat (Seiner and Shultz, 1980)

Feeding diets containing low levels of lipid result in higher

proportions of FA synthesized de novo in the mammary gland with

re-sultant lower yields of C18 FA and as much as 50% of palmitic acid Alteration of milk FA composition from dietary fats may occur as a

result of one or more fatty acids: 1) being absorbed and transported

to the mammary gland, where it is esterified unaltered and appearing

at a higher rate in the milk; 2) altered by rumen hydrogenation,

appearing in the mammary gland in hydrogenated form after eventual

esterification; 3) becoming desaturated before esterification,

ap-pearing in the milk as a fatty acid unrelated to the dietary fatty

acid; 4) occurring in large enough amounts to affect de novo FA

syn-thesis by inhibiting mammary gland uptake of FA, inhibiting one of

the enz3niies involved in FA synthesis; or 5) affecting rumen VFA bolism, reducing the availability of low molecular weight substrates required for FA synthesis (Christie, 1979) Origins of C4-C14 FA

meta-are entirely endogenous, all C18 FA meta-are exogenous, and C16 and C16:l

FA may have contributions from both endogenous and exogenous sources (Smith et al., 1978; Christie, 1979)

Cottonseed Meal Gossypol, 1,1'6,6',7,7'-hexahydroxy-5,5'-diisopropyl-3,3'-

dimethyl(2,2'-binapthalene)-8,8'-dicarboxaldehyde, is a naturally

occurring substance in cottonseed meal A yellow pigment, located

in the intercellular structures called pigment glands distributed

throughout the cotyledons and periphery of the axial tissue in glanded varieties of cottonseed (Martinez et al., 1970) , gossypol inhibits

17 feeding patterns of deleterious insects on cotton plants (Bottger

et al., 1964) Gossypol has gained a substantial amount of interest because it is a toxic substance to monogastric animals (Gallup, 1928), particularly young poultry and swine (Church, 1977)

Symptoms of gossypol toxicity summarized by Lindsey et al (1980) include: 1) anorexia; 2) decreased hemoglobin due to the formation

of gossypol-iron complex which interferes with either iron absorption

or utilization after absorption resulting in a decrease of available iron to the liver (Brahman and Bressani, 1975); 3) hypoproteinemia as

a result of extensive liver degeneration; 4) decreased hematocrit

(Brahman and Bressani, 1975); and 5) dyspnea Gossypol is naturally detoxified in monogastrics by accumulation of free gossypol in the

liver (Albrect et^ al., 1970) where it is metabolized and excreted

in the bile (Lindsey et a]^. , 1980) and in ruminants through

perma-nent binding with soluble proteins in the rumen (Reiser and Fu,

1962) Detoxification of gossypol by treatment with ferrous sulfate has alleviated symptoms of toxicity in rats, poor performance in

growing-finishing pigs, accumulation of gossypol in the liver of

pigs fed CSM (Rincon et al., 1980) and increase DM intake and daily gain in calves fed WCS (Cummins and Hawkins, 1982) Lindsey et al

(1980) reported high levels of total, free and bound gossypol in the liver of lactating cows fed either solvent extracted (Sol CSM) or

screw press CSM (SPCSM) indicating insufficient detoxification of

gossypol in the rumen Cows fed the Sol CSM had the highest levels, consumption of gossypol in this group reaching 54.5 mg/kg/d Feeding either Sol CSM or SPCSM decreased hemoglobin due to hemolysis of

extravascular erythrocytes, decreased hematocrit and increases in

temperature and respiratory rate during hot weather The necropsy

of one cow that died during hot weather revealed severe fatty eration of hepatocytes Hollon el^ al (1958) showed the tolerance

degen-of free gossypol ingestion in ruminants to be associated with age

and corresponding functional development of the rumen They found

a high correlation between free gossypol consumption greater than

140 mg/cwt/d and death within 48 d in calves fed CSM as the primary

protein source Symptoms described were erratic appetite, one to

two wk, and abdominal pain and dyspnea one to two days prior to

death; bright red blood slow to coagulate; hydrothorax and

hydroper-eritoneum; and fatty degeneration of liver tissue Serum

transam-inases increased corresponding to increased levels of gossypol due

to cellular destruction of primary hepatic and heart muscle cells

decreasing the concentration of liver transaminases (Brahman and

Bressani, 1975)

Commercial extraction of the oil from cottonseed, whether by

solvent or pressure methods, involves using heat and moisture

(Mar-tinez et al., 1970; Church, 1977) which can decrease the nutritional value of CSM by formation of an insoluble gossypol-protein complex

(Smith et^ al^ , 1959) resistant to in vitro digestion of trypsin and

pepsin (Sherrod and Tillman, 1962) This complex is formed by

bind-ing of lysine (Baliga and Lyman, 1957; Martinez ^ al., 1964)

epsi-lon-amino groups with two reactive carbonyl groups of gossypol

(Lyman et^ _al., 1959) decreasing the availability of lysine and other amino acids (Jones and Smith, 1977 a,b), resulting in poor growth

19 rates in rats (Smith £ ^ al , 1959; Lyman e^ al., 1959; Jones and

Smith, 1977a) and significantly lower digestibility of cottonseed

protein in sheep (Sherrod and Tillman, 1962) Craig and Broderick

(1981) reported only minimal losses of lysine availability in SPCSM and Sol CSM autoclaved less than sixty min The authors suggested

that more severe heat treatment, greater than what normally occurs

during oil extraction, must occur before any substantial availability

of lysine is realized Other workers (Wong et al., 1972; Finlay

et al^., 1973; Meisner ^ ^ , 1978) have described a reaction of

gossypol with the epsilon-amino groups of two lysine residues of

pepsinogen to form a zymogen which completely inhibits the

conver-sion of pepsinogen to its active form, pepsin

Moore (1914) and McCandlish (1921) reported trends towards

de-creased milk yields and percent fat x>7hen CSM replaced linseed meal

(LSM) and(or) wheat bran and an overall increase in percent and yield

of milk fat, without any influence on milk yields, when CSM replaced cracked corn (McCandlish, 1921) Milk and butterfat were increased

in cows fed CSM (up to 11 lb) compared to LSM without affecting herd health (Huffman and Moore, 1930) Cottonseed meal fed as the only

concentrate (Miller and Wise, 1944) depressed percent fat, TS and

SNF after four mo on the treatment When placed on pasture, several cows on the CSM treatment displayed anorexia, decreased milk produc-

tion and abortions Lindsey et^ £l^ (1980) found no effect on milk

production, percent fat or TS in cows fed either SPCSM or Sol CSM

compared to soybean meal

EFFICACY OF WHOLE AND PROCESSED COTTONSEED ON DIGESTIBILITY, RUMEN VARIABLES AND THE PRODUCTION OF MILK AND ITS COMPONENTS

Summary Four, first lactation, Holstein cows were used in a 4 X 4 Latin square design, lactation and digestion study Whole "fuzzy" cotton-seed (WCS), pelleted whole cottonseed (PCS), cottonseed meal (CSM)

or pelleted delinted cottonseed (PDLCS) were used in isonitrogenous, isofibrous diets fed at 3.5% of body weight per cow per day Animals were adjusted to treatment for 10 d followed by 7 d total collection

of feces for determination of dry matter digestibility Feed sals were weighed and sampled for subsequent analysis Rumen fluid samples were analyzed for pH and volatile fatty acids Milk samples obtained during collection periods were analyzed for butterfat (BF), total solids (TS), solids-not-fat (SNF), protein, and free fatty

refu-acids (FFA) Treatment means for milk production (kg), BF (%), milk protein (%) and dry matter digestibility (%) were: 20.85, 2.93,

3.42, 70.74; 19.48, 2.03, 3.61, 69.52; 20.18, 2.18, 3.39, 71.07;

20.13, 2.71, 3.41, 72.20 for the WCS, PCS, CSM and PDLCS diets, spectively A production study was conducted utilizing 83 lactating Holstein and Jersey cows to determine the effects of feeding WCS,

re-PCS and CSM on milk production, BF and alfalfa hay consumption

Animals were allotted to a 3 X 3 Latin square design according to

breed, stage of lactation and number of previous lactations Diets

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